Reliability Analysis* State Estimation * Dynamic Modelling (DSL) * System Dynamics (RMS / EMT) Motor Starting * Real-Time Simulation* Small Signal Stability * Interfacing PowerFactory * Installation Options
Rev 1.14/4/2010
PowerFactory V14 Basic Software Features & Calculation Functions Advanced Functions and Features Protection Coordination * Distribution Network Optimization * Harmonic Analysis * Optimal Power Flow Reliability Analysis * State Estimation * Dynamic Modelling (DSL) * System Dynamics (RMS / EMT) Motor Starting * Real-Time Simulator * Small Signal Stability * Interfacing PowerFactory * Installation Options
Rev 1.16/7/2011 1.16/7/2011_E _E
Table of Contents
Table Table of Contents 1 I nt ro du ct io n ................... ............................. .................... .................... .................... .................... .................... .................... .................... .................... ............. ............. .................... ............ .. 6 2 PowerFactory Overview .................................................................................................................... 8 2.1 Functional Integration and Applications ................ ............................ ....................... ....................... ........................ ....................... .................... .................... ................... ........ 8 2.2 PowerFactory Software Concept ....................... .................................. ....................... ........................ ....................... ....................... ........................ ....................... ................... ........ 8 3 Ne tw or k M od el s ........................... ..................................... .................... .................... ................... ................... .................... .................... .................... .............. .............. ................ ...... 11 3.1 Grid Representations and Power Equipment ............................ ........................................ ....................... ....................... ........................ .................... .................. .......... 11 3.2 Built-in Calculation and Integrated Modelling Functions ............. ......................... ........................ ........................ ........................ .................... ................ ........ 15 3.3 Load and Generation Profiles ................... ............................... ........................ ....................... ....................... ........................ ........................ .................... .................... ................. ..... 15 4 Da ta M an ag em en t .................... .............................. .................... ................... ................... .................... .................... .................... .................... .................... ................... .............. ..... 16 4.1 V14 Standard Data Model .................. .............................. ....................... ....................... ........................ ....................... ....................... ....................... ....................... ..................... ......... 16 4.1.1 Arrangement of Data in Project Folders ............. ......................... ....................... ....................... ........................ ........................ ...................... ..................... ............. .. 16 4.1.2 Study Time ........................................................................................................................................ 17 4.2 Data Organisation ................................................................................................................................... 17 5 Ne tw ork Dia gra ms & Gra ph ic Cap ab ili ti es ......... ............. ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... 19 6 Re su lt s a nd R ep or ti ng ............. ...................... ................... .................... .................... .................... .................... .................... .................... ................... .............. ............... ............ 22 6.1 Text Reports........................................................................................................................................... Reports...........................................................................................................................................
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6.2 Spreadsheet Reports (Tabular Views)...................... .................................. ....................... ....................... ........................ ....................... ....................... ....................... ........... 22 6.3 Reporting in Network Diagrams ............................................................................................................... 23 6.4 Result File Management .......................................................................................................................... 23 6.5 Plots and Diagrams ................................................................................................................................. 23 6.6 Additional Features ................................................................................................................................. 25 7 External Data Format Support ........................................................................................................ 26 7.1 Standard Data Formats ........................................................................................................................... 26 7.2 DIgSILENT Data Base Level Exchange (DGS)..................... (DGS)................................. ........................ ....................... ....................... ........................ .................... ............ .... 26 8 DP L- DI gS IL EN T Pr og ram mi ng La ng ua ge ...... .......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... 2 7 9 PowerFactory Modes of Operation .................................................................................................. 29 9.1 Standard Windowing Mode............................. ......................................... ........................ ....................... ....................... ........................ ....................... ....................... ................... ....... 29
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Table of Contents
Table Table of Contents 1 I nt ro du ct io n ................... ............................. .................... .................... .................... .................... .................... .................... .................... .................... ............. ............. .................... ............ .. 6 2 PowerFactory Overview .................................................................................................................... 8 2.1 Functional Integration and Applications ................ ............................ ....................... ....................... ........................ ....................... .................... .................... ................... ........ 8 2.2 PowerFactory Software Concept ....................... .................................. ....................... ........................ ....................... ....................... ........................ ....................... ................... ........ 8 3 Ne tw or k M od el s ........................... ..................................... .................... .................... ................... ................... .................... .................... .................... .............. .............. ................ ...... 11 3.1 Grid Representations and Power Equipment ............................ ........................................ ....................... ....................... ........................ .................... .................. .......... 11 3.2 Built-in Calculation and Integrated Modelling Functions ............. ......................... ........................ ........................ ........................ .................... ................ ........ 15 3.3 Load and Generation Profiles ................... ............................... ........................ ....................... ....................... ........................ ........................ .................... .................... ................. ..... 15 4 Da ta M an ag em en t .................... .............................. .................... ................... ................... .................... .................... .................... .................... .................... ................... .............. ..... 16 4.1 V14 Standard Data Model .................. .............................. ....................... ....................... ........................ ....................... ....................... ....................... ....................... ..................... ......... 16 4.1.1 Arrangement of Data in Project Folders ............. ......................... ....................... ....................... ........................ ........................ ...................... ..................... ............. .. 16 4.1.2 Study Time ........................................................................................................................................ 17 4.2 Data Organisation ................................................................................................................................... 17 5 Ne tw ork Dia gra ms & Gra ph ic Cap ab ili ti es ......... ............. ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... 19 6 Re su lt s a nd R ep or ti ng ............. ...................... ................... .................... .................... .................... .................... .................... .................... ................... .............. ............... ............ 22 6.1 Text Reports........................................................................................................................................... Reports...........................................................................................................................................
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6.2 Spreadsheet Reports (Tabular Views)...................... .................................. ....................... ....................... ........................ ....................... ....................... ....................... ........... 22 6.3 Reporting in Network Diagrams ............................................................................................................... 23 6.4 Result File Management .......................................................................................................................... 23 6.5 Plots and Diagrams ................................................................................................................................. 23 6.6 Additional Features ................................................................................................................................. 25 7 External Data Format Support ........................................................................................................ 26 7.1 Standard Data Formats ........................................................................................................................... 26 7.2 DIgSILENT Data Base Level Exchange (DGS)..................... (DGS)................................. ........................ ....................... ....................... ........................ .................... ............ .... 26 8 DP L- DI gS IL EN T Pr og ram mi ng La ng ua ge ...... .......... ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... 2 7 9 PowerFactory Modes of Operation .................................................................................................. 29 9.1 Standard Windowing Mode............................. ......................................... ........................ ....................... ....................... ........................ ....................... ....................... ................... ....... 29
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9.2 Engine & Hybrid Execution Mode ............................................................................................................. 29 10 P ow er F lo w An al ys is ............................ ..................................... ................... .................... .................... .................... .................... .................... ................. ................. ............. ... 30 11 Fa ul t An al ys is .................... .............................. .................... .................... .................... .................... .................... .................... .................... ................... ................... ................... ......... 33 11.1 Supported Standards ............................................................................................................................. 33 11.2 Complete Method/Multiple Faults ....................... .................................. ....................... ........................ ........................ ........................ .................... ................... ................. ...... 34 11.3 Fault Analysis Results (all Methods)........................................................................................................ Methods) ........................................................................................................ 35 12 N et w or k R ed uc ti on .................... .............................. ................... ................... .................... .................... .................... .................... .................... ................. ................. ............. ... 36 12.1 General Features .................................................................................................................................. 36 13 Voltage Stability Analysis .............................................................................................................. 37 13.1 PV Curves ............................................................................................................................................. 37 13.2 Q-V Analysis ......................................................................................................................................... 37 14 Lo ad Fl ow Se ns it iv it ie s .................... .............................. .................... ................... ................... .................... .................... .................... .................... .................... ............... ..... 38 15 Contingency Analysis .................................................................................................................... 39 16 Ove rh ea d L in e a nd Cab le Pa ra me te r C alc ul at io n ........ ............ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... .. 41 16.1 Overhead Line Parameter Calculation ....................... ................................... ........................ ....................... ....................... ........................ ................... ................... ............ 41 16.2 Cable Parameter Calculation ....................... .................................. ....................... ........................ ........................ ........................ ....................... ................... .................... .............. 41 17 Distribution Network Analysis ...................................................................................................... 42 17.1 Feeder Analysis ..................................................................................................................................... 42 17.2 Low-Voltage Network Analysis ....................... ................................... ........................ ....................... ....................... ........................ ....................... ...................... .................. ....... 42 17.3 Stochastic Load Modelling................. ............................ ....................... ........................ ....................... ....................... ....................... ....................... ........................ .................... ........ 42 17.4 Cable Reinforcement Optimization.......................................................................................................... Optimization.......................................................................................................... 43 17.5 Feeder Tools ......................................................................................................................................... 44 18 P ro te ct io n F un ct io ns ...................... ................................ .................... .................... .................... .................... .................... .................... .................... .............. .............. ............ 45 18.1 Protection Model Library and Functionality...................... .................................. ........................ ....................... ....................... ........................ ....................... ............. .. 45 18.2 Output & Graphical Representation ............................ ........................................ ....................... ....................... ........................ ....................... .................... .................. ......... 47 18.3 Overcurrent-Time Protection................................ ........................................... ....................... ........................ ....................... ....................... ........................ ....................... ............. 48 18.4 Distance Protection ............................................................................................................................... 48 19 Dis tr ib ut io n Ne tw or k Opt im iza ti on ........ ............ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ........ ...... ...... ...... 50 19.1 Optimal Capacitor Placement ................................................................................................................. 50
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19.2 Open Tie Optimization........................................................................................................................... 50 20 Harmonic Analysis Functions ........................................................................................................ 52 20.1 Harmonic Load Flow .............................................................................................................................. 52 20.2 Frequency Sweep .................................................................................................................................. 53 20.3 Ripple Control Signals ........................................................................................................................... 54 20.4 Filter Rating .......................................................................................................................................... 54 21 Op ti m al P ow er Fl ow ...................................................................................................................... 55 21.1 AC Optimization .................................................................................................................................... 55 21.2 DC Optimization .................................................................................................................................... 56 22 R el ia bi li ty An al ys is ........................................................................................................................ 58 22.1 Failure Models ...................................................................................................................................... 58 22.2 State Enumeration ................................................................................................................................ 59 22.3 Failure Effect Analysis ........................................................................................................................... 59 22.4 System Indices and Results ................................................................................................................... 60 22.5 Special Features.................................................................................................................................... 62 22.5.1 High Flexibility ................................................................................................................................. 62 22.5.2 Tracing of Individual Cases ............................................................................................................... 62 22.5.3 Powerful Output Tools for Result Representation ............................................................................... 62 22.5.4 Contribution to Reliability Indices ...................................................................................................... 63 22.5.5 Development of Indices over Years ................................................................................................... 63 23 St at e Est im at io n ............................................................................................................................ 64 24 Dy na mi c Mo de lli ng Fle x ib ili ty (D SL ) ............................................................................................. 6 6 25 P ow er S ys te m D yn am ic s ............................................................................................................... 68 25.1 General Capabilities ............................................................................................................................... 68 25.2 Stability Analysis Functions .................................................................................................................... 71 25.2.1 RMS Simulation with a-b-c Phase Representation ............................................................................... 71 25.2.2 Long-term Stability........................................................................................................................... 71 25.3 Transient Motor Starting........................................................................................................................ 72 25.4 Electromagnetic Transients (EMT) .......................................................................................................... 73 25.5 Dynamic System Parameter Identification............................................................................................... 74 25.6 PowerFactory Real-Time Simulators ....................................................................................................... 74 26 Small Signal Stability .................................................................................................................... 76
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Table of Contents
27 P ow er Fa ct or y I nt er fa ce s ............................................................................................................... 78 27.1 DGS Interface ....................................................................................................................................... 78 27.2 OPC Interface ....................................................................................................................................... 78 27.3 Shared Memory Interface ...................................................................................................................... 79 28 I nt er fa ci ng P ow er Fa ct or y ............................................................................................................. 81 28.1 PowerFactory - GIS integration .............................................................................................................. 81 28.2 PowerFactory - SCADA integration ......................................................................................................... 83 28.3 PowerFactory - Simulation Interface (SIMULINK, etc.)............................................................................. 84 28.4 PowerFactory - A/D Signal Interfacing Capability..................................................................................... 84 29 Po w erF act or y In sta lla ti on Opt io ns ............................................................................................... 85 29.1 PowerFactory Workstation License ......................................................................................................... 85 29.2 PowerFactory Server License ................................................................................................................. 86 29.3 License Overview .................................................................................................................................. 90 29.4 Installation Requirements ...................................................................................................................... 90 30 Po w erF act ory Fun cti on Def in it io ns a nd Pr ice s ............................................................................. 91 30.1 PowerFactory Function Definitions ......................................................................................................... 91 30.2 PowerFactory Prices .............................................................................................................................. 92 31 Th e DI gS I LE NT C om pa ny .............................................................................................................. 93 32 Hi sto ry of th e DI gS IL ENT So ftw ar e .............................................................................................. 94
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1 Introduction
1 Introduction DIgSILENT has set standards and trends in power system modelling, analysis and simulation for more than 25 years. The proven advantages of the PowerFactory software are its overall functional integration, its applicability to the modelling of generation-, transmission-, distribution- and industrial grids, and the analysis of these grids’ interactions. Electrical grids, planning processes and operation processes are becoming increasingly complex due to market unbundling, expansion of interconnections and distributed generation. This increases the demands on software tools in terms of data quality, flexibility and manageability. With Pow erFactory Version 14, DIgSILENT presents a further step towards seamless integration of functionality and data management within a multi-user environment. The building and organizing of schemes, scenarios, versions and running arrangements has been added for improved handling. Version 14 K ey Features
Single- and multi-user project data administration environment
Database with historical data storage and auditing functionality.
Time-stamped data model
Management of operational scenarios
Baselining, versioning and publishing of models
Integrated node and branch, and switch and component modelling
Integrated overview diagrams, simplified and detailed single line diagrams
Fast contingency analysis tools (AC and DC load flow)
Contingency-constrained economic dispatch including quad booster optimization
Distributed/embedded power generation modelling
New models for wind power and virtual power plants
DIgSILENT PowerFactory is the most economical solution, as data handling, modelling capabilities and overall functionality replace a set of other software systems, thereby minimizing project execution costs and training requirements. The all-in-one PowerFactory solution promotes highly-optimized workflow.
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1 Introduction
DIgSILENT PowerFactory is easy to use and caters for all standard power system analysis needs, including highend applications in new technologies such as wind power and distributed generation and the handling of very large power systems. In addition to the stand-alone solution, the PowerFactory engine can be smoothly integrated into GIS, DMS and EMS supporting open system standards.
DIgSILENT PowerFactory v1 4 integrated features overview
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2 P o w e r F ac t o r y O v e r v i e w
2 PowerFactory Overview 2.1 Functional Integration and Applications
Implemented as a single software solution allowing for fast 'walk around' through the database and execution environment
No need to reload modules and update, transfer and convert data and results between different program applications
Vertically integrated power equipment model concept allowing models to be shared by all analysis functions
Support of transmission-, distribution- and industrial system design and simulation
Modelling and simulation of railway systems
Simulation of any kind of wind turbines and wind parks
Smart Grid modelling including virtual power plants and distributed generation such as P Vpanels, micro turbines, battery storage, CHP, etc.
2.2 PowerFactory Software Concept Single Database Concept
Optimal data organization and project definitions for performing any type of calculation, storage of settings, diagrams and visualization options or software operation sequences.
No need for tedious organization of several files for defining the various analysis aspects and project execution workflows.
Database environment fully integrates all necessary data, such as that required for defining cases, scenarios, variants, single-line graphics, outputs, run conditions, calculation options, graphics or userdefined models. Saving a project includes everything required to rerun all defined cases at a later stage.
Access to all data via a comfortable and powerful data manager, object browser, plus various types of diagrams and wizards. Comprehensive, non-redundant data model supporting all calculation functions
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2 P o w e r F ac t o r y O v e r v i e w
User Roles
Access to user information through a user accounting system
Protection of data through different types of access rights
Folder sharing between users with “read-only” access. This is especially useful for libraries and network base cases which should be administrated only by authorized personnel.
Multi-User Operation and Team w orking
Multi-user data administration supporting MS-SQL or ORACLE databases
Support of user accounting, access rights and data sharing, featuring the powerful option of allowing several users to work on the same project in a coordinated way. This demonstrates the concept of nonredundant data management in PowerFactory..
Management of multi-user data editing via the definition of a base project, project versions and derived projects (virtual projects).
Support of version control including rollback functions and merge/compare tools.
Netw ork Variations, Expansion Stages Management and Operational Scenarios
Support of time-stamped network variations.
Variation scheduler for easy handling of sub-projects
Definition of study cases and operational scenarios
Activation of network stages according to study time. This automatically addresses the handling of power system components according to their commissioning and de-commissioning dates
Multi-Level Models
Data describing network models such as cables, machines, loads, transformers, etc., are subdivided into element data and type data which point to libraries. All data to be entered are grouped into basic data (data required for all calculations) and function level data (data required only for executing specific calculations). Data are simply entered in physical quantities rather than in per unit values, minimizing the need for manual recalculation and conversion of data. Verification of input data, with detailed warning and error messages
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2 P o w e r F ac t o r y O v e r v i e w
Integrated calculators for asynchronous machines, cable data and tower configurations
Batch Mode, Engine Mode and I nterfaces
Fully interactive windowing mode according to the latest, proven standards
Engine mode for background operation
Various communication features to exchange data with other applications such as GIS, SCADA and realtime control systems via OPC, shared memory, DGS (CSV, ODBC), etc.
Hybrid operation switching between background and windowing mode according to users’ needs
Data exchange via CIM, PSS/E, UCTE and many other file formats
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3 Network Models
3 Network Models 3.1 Grid Representations and Power Equipment Grid Models
Meshed and radial AC systems with 1-, 2-, 3-, and 4-phases
Meshed and radial DC systems
Combined AC and DC system modelling
Model validity from LV up to ultra-high voltage
Phase Technologies
Single phase with/without neutral
Two-phase with/without neutral
Bi-phase with/without neutral
Three-phase with/without neutral
Substations
Simple terminal models to be used for “node and branch” representation, marshalling panels, terminal blocks, terminal strips, clamping bars, joints and junctions.
Complex substation models with the provision of various standard busbar configurations such as single- and double busbars with/without tie-breakers, bypass busbars, 1½ busbar systems and flexible busbar configurations according to user-specific needs.
Templates for holding any type of user-specific busbar configuration, including pre-configured protection schemes
Generators and Sources
Synchronous and asynchronous generator
Doubly-fed induction generator
Static generator (for PV, fuel cell, wind generator, battery storage, etc.)
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3 Network Models
External grid
AC voltage source
AC current source
2-terminal AC voltage source
Loads
General load model (for HV and MV-feeders)
Complex load model (for feeders with a large number of induction motors)
Low voltage load (can be assigned across line and cable sections)
Reactive Power Compensation
Static Var Compensator (SVC)
Shunt/Filter (RLC, RL, C, RLCR p, RLCCR p)
Branch models
Overhead line and cable models (π-models and distributed parameter models)
Circuits and line sub-sections
Mutual data, line couplings, tower geometries
2-, 2-N-winding transformer and auto transformer
3-winding transformer, booster transformer
Series reactor, series capacitor and common impedance
DC Models
1-terminal and 2-terminal DC voltage source and DC current source
DC/DC converter
Inductive DC-coupling
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3 Network Models
Pow er Electronics Devices
Thyristor/Diode converter models
Self-commutated converter models (VSC-converter)
DC valve (for building individual converter topologies)
Softstarter
Switches and Substation Equipment
Circuit Breaker and Disconnector
Load-Break-Disconnector
Load-Switch
Grounding Switch
Fuse
NEC/NER, grounding devices
Surge arrester
Composite Models
Composite node models, e.g. representing complex substations
Composite branch models
Template library for handling composite models
Parameter characteristics
Time characteristics and discrete characteristics
Scalar, vector and matrix characteristics
File references and polygons
Continuous and discrete triggers
Frequency and time scales
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3 Network Models
Controllers
Station controller, secondary controller (SCO), virtual power plant
Tap controller, shunt controller
User-definable capability diagrams and controllers
Organisation and Grouping
Site, station, substation, area, zone
Feeder, branch, bay
Operator, owner
Boundaries
Operational Library
Substation running arrangements
CB ratings
Thermal ratings
Library of faults/contingencies
Library of (planned) outages
Others
Protection relays with over 30 basic protection function blocks
Manufacturer-specific relay library with relay models from all major manufacturers
CT, VT and various measurement transducers (P, Q, f, etc.)
Fourier source, harmonic source, FFT
Clock, sample & hold, sample & hold noise generator
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3 Network Models
PowerFactory supports 500 different objects for defining, organizing and storing users’ grid definitions and project settings. The above-listed objects are a summary of those most frequently used.
3.2 Built-in Calculation and Integrated Modelling Functions PowerFactory provides a number of functions which assist users in entering data which may have come from datasheets or product catalogues. Not only do these functions greatly simplify data entry, but they also provide valuable output and results. Identification of asynchronous machine parameters
Support of two different parameter input modes: (a) electrical parameters and (b) slip-torque/current characteristic
When entering electrical parameters, such as the rated mechanical power, stator resistance and reactance, magnetisation reactance, etc., all electrical parameters which precisely define and describe the asynchronous machine are then calculated. This includes the determination of the torque-/speed characteristic.
The alternative definition via the slip-torque/current characteristic requires entering data such as characteristics at nominal operation point, torque at stalling point, locked rotor torque and other parameters typically available from manufacturer handbooks or test reports. This alternative data entering method will then determine the electrical machine parameters.
Calculation of Overhead Line Parameters and Cable Param eters Please refer to section 16.
3.3 Load and Generation Profiles
Load and generator parameter characteristics can be defined on a per-element basis for parametric studies. Parameter characteristics can be imposed on each input parameter. They may be timedependent, refer to predefined discrete cases, or result from external sources. All operational data (generation and demand patterns, switch positions, etc) can be saved and maintained in distinct Operation Scenarios.
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4 Data Management
4 Data Management 4.1 V14 Standard Data Model 4.1.1 Arrangement of Data in Project Fold ers All data required for grid modelling, project organization and project execution are arranged in project folders. Project data are structured into Libraries, Network Models, Operation Scenarios and Study Cases. Libraries
Libraries contain equipment types, special operation information, DPL scripts, templates and userdefined models.
The Equipment Type Library can store manufacturer and standard data for cables, conductors, circuit breakers, transformers, motors, generators, protection devices, PV panels, converters, wind turbines, etc.
Operational Libraries help organize standard settings and operational structures of grids. Typical entries include specific device Mvar limits and capability curves, outages, fault conditions and sequences, specific thermal ratings, running arrangements, etc.
Network Models
All network data are organized and stored in various folders such as grid- and area folders, folders for boundaries, circuits, feeders, routes, zones, etc.
Comprehensive network topology handling defining: Nodes, Substations, Sites, Boundaries, Circuits, Routes, Operators and Owners.
Graphical information such as overview diagrams, simplified single line diagrams and detailed single line diagrams are automatically organized in a separate diagram folder
Grid Variations are linked to the original grid data, allowing non-redundant grid variation management.
Easy and non-redundant handling of grid expansion alternatives.
Planned grid expansions are organized by time-stamped Expansion Stages which are considered depending on the selected Study Time. Expansion Stages are stored in Variations and handled via the Variation Scheduler . In other words, variations can be seen as expansion plans composed of different stages which are activated chronologically.
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4 Data Management
Operation Scenarios
Definition of operation and dispatch conditions, grid loading, ambient temperature, daily load variation pattern, etc
Organisation of characteristics to generate ranges of values such as daily load curves, temperature dependencies, wind conditions, solar radiation pattern, etc
Definition of triggers for easy selection of certain conditions to be analysed
Comparison of Operation Scenarios
Study Cases
Grid configurations, operation conditions, trigger settings, calculation options, fault sequences, results and DPL scripts to be executed are all stored in Study Cases
Study Cases can be activated to reproduce any grid condition and its associated calculation results
4.1.2 Study Time PowerFactory V14 extends grid modelling into the dimension of time. The model may span a period of months or years considering network expansions, planned outages and other system events. The period of validity of a project therefore specifies the time span that the of the model’s validity.
The Study Time automatically determines which expansion stages of a variation will be considered.
Selection of Study Time along with the operational conditions will automatically create grid expansion scenarios
4.2 Data Organisation Simultaneous use of grid data takes place when two different parties work with the same project. This kind of situation occurs most frequently in larger companies where software-based teamworking capabilities are a basic requirement. Versioning
Project Versions constitute a snapshot of a project at a specific point in time
Project versions are under full control of owner rights
Rollback functions allow a controlled “Undo” of a project’s execution steps, thereby “rolling back” to a specific stage of the project
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4 Data Management
Reporting facilities for Derived Projects which depend on a certain version
Derived Projects
Master Projects can be published in a public area of the database
Derived Projects are “virtual” copies of a Version of a Master Project that can be developed by any number of users simultaneously. Only the differences to the original version are stored
Derived Projects are always linked to their original Master Project
The users will be automatically notified if a new version of their Master Project is available
Comprehensive tools for merging several derived projects and/or their versions into a new project via the Merge Tool. This allows the consolidation of independent and parallel model modifications introduced by different users.
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5 Network Diagrams & Graphic Capabilities
5 Network Diagrams & Graphic Capabilities Categories of Netw ork Diagrams
Simplified Single Line Diagrams with various options for a schematic view of substation topology and switching status
Detailed Single Line Diagrams showing all switches (circuit breakers and disconnectors)
Intelligent Overview Diagrams providing a node and branch representation of the network. Can be schematically, geographically or semi-geographically arranged
General Features
Handle mixed representations of Detailed Single Line Diagrams, Simplified Single Line Diagrams and Overview Diagrams Access equipment editing menus in the single line diagram via cursor selection of the appropriate element, region or composite model
Zoom-in or zoom-out of area networks or composite model graphics
Initiate calculation events directly within the graphical environment, including circuit breaker switching, fault implementation and other data changes
Option to immediately reflect any editing activity on the graphical level
Display any calculation results immediately in result boxes in single line diagrams. All program variables and signals can be displayed according to a highly flexible user definition for various object categories and analysis functions
Display any calculation result to be defined on various functional levels and categories for any object
Insert freely-configured result displays
Provision of auxiliary graphics editing for enhanced documentation
Perform copy/paste operation on single objects and groups
View and operate several graphic windows with different layers and grid sections simultaneously. Utilize several graphical representations of the same system simultaneously. Spread large diagrams over several pages
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5 Network Diagrams & Graphic Capabilities
Support of pre-defined and user-defined graphical layers
Placement of user-definable icons as buttons for executing DPL scripts. This way users can create custom panels of frequently-executed DPL-initiated commands.
Colouring of Network Diagrams
Provision of various colouring modes according to topology criteria such as areas, zones, owners, operators, routes, station connectivity, energizing status, boundaries/interior regions, isolated grids, etc.
Colouring options to display voltage levels, equipment loading and operation ranges
Define colouring based on AC/DC equipment category and phase technology
Display of grid modifications and variants, recording of expansion stage modifications, missing grid connections
Provision of feeder colouring and path definitions
User-defined filters based on complex equations or DPL scripts
User-definable Symbols
Support of user-definable symbols based on standard graphical formats (.wmf,.bmp). E.g. use your own symbols for wind turbines, PV panels, hydro units, etc.
Define specific graphical representations for transformers, shunts, circuit breakers, isolators to fit individual needs.
Composite Graphics
Elements can be grouped together and stored as Composite Graphics. Typical applications are standard busbar arrangements, switchboard configurations, HVDC structures, PV panels, typical wind turbine configurations or complete wind parks.
Composite Graphics can be easily handled via the Template Manager. Templates can be populated with type and element data. For drawing Composite Graphics, the Template Manager is operated as Drawing Tool Box.
Virtual Instrum ents
DIgSILENT PowerFactory applies the concept of Virtual Instruments (VI) as a tool for displaying any calculated result or variable.
Results may be displayed in the form of bar graphs, plotted curves, or even tables of values, with all of these representations being completely user-definable.
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5 Network Diagrams & Graphic Capabilities
VIs are used to display protection curves, harmonics analysis results or to view electrical variables from any location in the network single line diagram, and any model variable during RMS and EMT simulations.
Many VIs provide additional built-in functionality such as curve labelling and measuring, scaling, curve fitting, filtering and digitizer functions.
Typical Virtual Instruments Available
x-t and x-y plots, bar diagrams, harmonic distortion diagram
Overcurrent-time-diagrams, distance-time diagrams, vector diagram, path diagram
Voltage sag diagram, waveform diagram
Eigenvalue diagram, phasor diagram
Bitmaps, buttons, DPL-command buttons, digital display
Curve-digitizing diagram
Text label
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6 Results and Reporting
6 Results and Reporting 6.1 Text Reports Automatic reports for calculation results, such as load flow, short-circuit, harmonic calculations, contingency calculation, reliability analysis, etc.
Numerous predefined reports for all key calculation functions
Flexible selection of elements for reporting
Reports can be user-configured allowing user-definable formatting
Automatic reports for documentation of network components, such as transformers, lines, generators, relay settings, etc.
Flexible selection of network components for documentation
Flexible selection of calculation module, e.g. report only input data required for load flow and shortcircuit
6.2 Spreadsheet Reports (Tabular Views)
Numerous predefined spreadsheet reports for all key calculation functions via “Flexible Data Pages”
User-definable setup of “Flexible Data Pages”. Tabular view of any combination of input parameters/ calculation results
Several “Flexible Data Page” definitions (variable selections) may exist concurrently
Independent variable selections for every calculation
Sorting facilities for tabular views
Automatic statistical summaries for values in tables
Flexible filters for selecting elements for output
Output facilities to: Output window, clipboard and clipboard with column headers for use in spreadsheet programs such as MS Excel
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6.3 Reporting in Network Diagrams
Concept of “result boxes” in network diagrams to flexibly display any element/type parameter, as well as any calculation result
Easy-to-configure “result box” format on both component and calculation levels
6.4 Result File Management More complex calculation results can be stored in “Result Files”, e.g. for calculations such as transient stability results, harmonic analysis results, contingency results, etc.
Allows easy configuration of outputs (plots, reports, etc…)
Accessible by post-processing through DPL
Export functionality to export result data to: -
Output window Clipboard (compatible with spreadsheet programs such as MS EXCEL) Text file (compatible with spreadsheet programs such as MS EXCEL) COMTRADE (for transient data) PowerFactory measurement file (ASCII)
6.5 Plots and Diagrams
DIgSILENT PowerFactory applies the concept of Virtual Instrum ents ( VI ) as a tool for visualizing calculation results as plots and diagrams. VIs are used to display (for example): - Results of RMS and EMT simulations (any pre-selected monitoring variable/signal) - Protection configurations and results (R-X diagrams, automatic time-distance diagrams, relay characteristics, etc) - Harmonic analysis results
Many VIs provide additional built-in functionality such as curve labelling and measuring, scaling, curve fitting, filtering and digitizer functions.
Selected List of Most Common Virtual Instrum ents:
Plots for simulation results
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6 Results and Reporting
Monitored variables/signals over time Trajectories
Harmonics -
Protection -
Eigenvalue calculation
Digital display Metering device (vertical/horizontal scales) Combination of both
Picture box for displaying graphic files. Supported file formats are: -
Eigenvalue diagram Phasor diagrams and bar diagrams (controllability, observability, participation)
Measurement VIs -
Bar diagrams Vector diagrams Path diagram x-y diagrams
Voltage sag diagram
Time-overcurrent diagrams Time-distance diagrams Relay characteristic diagram
Additional diagrams for results of load flow, short circuit, harmonics, etc.: -
Harmonic distortion diagram FFT diagrams Waveform plots
Windows metafiles (*.wmf) AutoCAD graphic file (*.dxf) Bitmaps (*.bmp)
Curve-digitizing diagram
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6.6 Additional Features The PowerFactory graphic windows such as the single line graphic, plots, and block diagrams, offer the following functionality:
Printing or plotting to any device supported by the Windows Print Manager to produce high quality graphical documents from within the program.
Export to standard file formats such as: - Windows Metafile (*.wmf) with high precision coordinates - Bitmap (*.bmp)
Conversion of graphic files between several file formats such as *.png, *.dxf, *.gif, *.tiff, *.eps, etc. This is achieved via an external tool which is shipped with PowerFactory.
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7 External Data Format Support
7 External Data Format Support 7.1 Standard Data Formats In many cases, migration of data from other power system software is required. PowerFactory therefore supports foreign file Import of several versions from the following software packages:
PSS/ E, PSS/U and PSS/ Adept (Siemens)
DV G and UCTE (ucte.org)
NEPLAN (BCP)
ISU (SAP , billing data)
NETCAL (STZ Konstanz), NEPS ( I+P Consult) and ReticMaster (Inspired In terfaces)
Foreign file Export is supported for P S S / E and UCTE. CI M object and format definitions are increasingly used for standardized data exchange. Although the CIM standards are still under development, PowerFactory already supports CIM import and export:
CIM 61970 (CIM for Transmission)
7.2 DIgSILENT Data Base Level Exchange (DGS) DGS is PowerFactory’s standard bi-directional interface specifically designed for bulk data exchange with other applications such as GIS and SCADA, and for example, for exporting calculation results to produce Crystal Reports, or to interchange data with any other power system software. DGS (“DGS”=DIgS ILENT-GIS-SCADA) does not feature the exchange of PowerFactory execution commands.
User-specific definition of objects and object parameters
Supported objects: elements, types and libraries, graphics and results
Import and export of complete network models as well as incremental data for updating existing models
Database support for: Oracle, MS-SQL and ODBC System DSN
File formats supported: ASCII Text (CSV), XML, MS-Excel and MS Access
Available for PowerFactory Interactive Window Mode and PowerFactory Engine Mode
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8 D P L - D I g S IL E N T P r o g r a m m i n g L a n g u a g e
8 DPL- DIgSILENT Programming Language The DPL-Programming Language offers a flexible interface for automating PowerFactory execution tasks. The DPL scripting language adds a new dimension to PowerFactory software by allowing the implementation of new calculation functions. Typical examples of user-specific DPL-scripts are:
Parametric sweep calculations (e.g. sliding fault location, wind profile load flows)
Implementation of user-specific commands (e.g. transfer capability analysis, penalty factor calculation)
Automatic protection coordination and device response checks
Specific voltage stability analysis via PV-/QV-curve analysis, etc.
Contingency screening according to user-specific needs
Verification of connection conditions
Data pre-processing including input/output handling
Equipment sizing and dimensioning
Report generation
The DPL object-oriented scripting language is intuitive and easy to learn. The basic set of commands includes:
C++- like, object-oriented syntax
Flow commands such as "if-then-else", "do-while"
Input/import, output/export and reporting routines
Mathematical expressions, support of vectors and matrices
Access to any PowerFactory object and parameter including graphical objects
Definition and execution of any PowerFactory command
Object filtering and batch execution
PowerFactory object procedure calls and DPL subroutine calls
N ew : Calling of external libraries (DLLs) for linking and executing other applications
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8 D P L - D I g S IL E N T P r o g r a m m i n g L a n g u a g e
Easy Development DPL’s basic syntax allows for the quick creation of simple high-level commands to automate tasks. Such tasks may include renaming objects, search and replace, post-processing calculation results and creating specific reports. Transparency All parameters of all objects in the network models are accessible. DPL can be used to query the entire database and to process all user-input and result parameters without restrictions. Standardizing Commands The DPL language can be used to create new 'standardized' DPL commands that can be used over and over again. DPL commands allow input parameters to be defined, and can be executed for specific selections of objects. Proven DPL commands can be safely stored in DPL command libraries and be used from there without the risk of damaging the scripts. Control DPL commands can configure and execute all PowerFactory commands. This includes not only the load flow and short-circuits calculation commands, but also the commands for transient simulation, harmonic analysis, reliability assessment, etc. New objects can be created by DPL in the database, and existing objects can be copied, deleted and edited. New reports can be defined and written to the output window; new graphs can be created and existing graphs can be adjusted to reflect a user-defined selection or the current calculation results. Modularity A DPL command may contain other DPL commands as subroutines. This modular approach allows the execution of subroutines as independent commands. Existing commands can be combined to quickly create more complex commands.
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9 P o w e r F ac t o r y M o d e s o f O p e r a t i o n
9 PowerFactory Modes of Operation 9.1 Standard Windowing Mode 9.2 Engine & Hybrid Execution Mode The standard execution of DIgSILENT PowerFactory is via the classical windowing mode operated via mouse and keyboard. When operated in “Engine Mode” PowerFactory is executed as a background process featuring a number of additional application options:
Bi-directional, high-speed exchange of data via “DIgSILENT Shared Memory Interface” or via “OPC” (OLE for Process Control). When using OPC, PowerFactory is executed as an OPC-Client.
Remote-execution of any PowerFactory command including activation of projects, modification of data, execution of analysis functions and DPL scripts, generation of output and reports, etc.
Temporary activation/popup of the “Windowing Mode” featuring interactive windowing operation u ntil the windowing mode is closed and the engine mode resumes (“Hybrid Operation Mode”).
In principle, a number of additional application features may be operated as background processes in situations where it is integrated into GIS/NIS or SCADA systems or linked with other simulation tools such as Matlab/SIMULINK, ASPENTECH’s process simulation tool or other software systems requiring interaction with network analysis procedures. The engine mode also features parallel processing with other PowerFactory processes. The “Engine Mode” permits the remote control of all PowerFactory functions with fast data and execution command exchange. Hybrid operation mode is supported by activating the Windowing Operation mode for combined operation.
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10 P o w e r F l o w A n a l y s i s
10 Power Flow Analysis Within the Load Flow analysis environment, the accurate representation of a variety of network configurations and power system components is possible.
DIgSILENT PowerFactory offers a selection of calculation methods, including a full AC Newton-Raphson technique (balanced and unbalanced) and a linear DC method. The enhanced non-decoupled NewtonRaphson solution technique with current or power mismatch iterations, typically yields round-off errors below 1 kVA for all buses. The implemented algorithms exhibit excellent stability and convergence. Several iteration levels guarantee convergence under all conditions, with optional automatic relaxation and modification of constraints. The DC load flow, solving for active power flows and voltage angles, is extremely fast and robust (linear system; no iterations required).
Any combination of meshed 1-, 2-, and 3-phase AC and/or DC systems can be represented and solved simultaneously, from HV transmission systems, down to residential and industrial loads at LV voltage levels. Neutral conductors can be modelled explicitly.
The Load Flow tool accurately represents unbalanced loads, generation, grids with variable neutral potentials, HVDC systems, DC loads, adjustable speed drives, SVSs and FACTS devices, etc., for all AC and DC voltage levels.
DIgSILENT PowerFactory offers a new, intuitive and easy-to-use modelling technique which avoids the definition of bus types such as SL, PV, PQ, PI, AS, etc. PowerFactory simply provides the control mechanisms and device characteristics which are found in reality.
More Load Flow A nalysis Features
Consideration of reactive power limits: detailed model for generator Mvar capability curves (including voltage-dependency).
Practical station control features with various local and remote control modes for voltage regulation and reactive power generation. Reactive power is automatically adjusted to ensure that generator output remains within its capability limits.
Various active power control modes, e.g. as dispatched, according to secondary or primary control, or inertial response.
Supports device characteristics, such as voltage-dependent loads and asynchronous machines with saturation and slip dependency, etc.
Comprehensive area/network power exchange control features using Secondary Controllers (SCO) with flexible participation factors.
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Transformer OLTC able to control local or remote bus voltages, reactive power flows and voltage-drop compensation (LDC) within distribution systems. Special transformer controller model for parallel transformers. Transformer tap adjustment supports discrete and continuous methods.
Device controllers for shunts, doubly-fed asynchronous machines and other power electronics elements such as self-commutated converters (VSC), thyristor/diode converters or integrated FACTS devices.
Local and remote control mechanisms for SVCs. Automatic and continuous control of TCR and TSC switching is performed within component ratings to hold the voltage at a given value.
Correct representation of transformer vector groups and phase displacement.
Shunts can be modelled to consist of a combination of series and/or parallel connected capacitors, reactors and resistors. Shunts can be connected to busbars and feeders or to the remote ends of cables and lines. Filters may consist of any number of shunt combinations, and automatic shunt switching can be included in the automatic voltage regulation.
Support of the Virtual Power Plant model for generator dispatch based on merit order algorithm.
Feeder load scaling to control power flows at feeder entry point – including nested and parallel feeders.
Full support of any parameter characteristic and scale to allow parametric studies or easy definition of loading scenarios or load profiles.
All operational data (generation and demand patterns, switch positions, etc) can be saved and maintained in distinct Operational Scenarios.
Further Special Functions
Analysis of system control conditions
Consideration of protection devices
Determination of ‘Power at Risk’
Calculation of Load Flow Sensitivities. Evaluation of expected active/reactive power flow and voltage changes in the network based on the effect of demand/generation or transformer tap change.
Support of DPL scripts; e.g. to perform load balancing, determination of penalty factors or any other parameter required.
Load Flow Results
Implicit calculation of a large number of individual result variables and summary figures
Display of any variable within the single line graphic, station diagram, and a tabular Flexible Data Page
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Various colouring modes for the single line graphic to visualize quantities such as calculated loading and/or voltage levels
Detailed analysis reporting, which can list overloaded system elements, unacceptable bus voltages, system islands, out-of-service components, voltage levels, area summaries, and more
Detailed textual output with pre-defined or user-defined filters and levels
DPL interactivity with all results
Result export to other software applications such as MS-EXCEL
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11 F a u l t A n a l y s i s
11 Fault Analysis DIgSILENT PowerFactory features fault calculation functionality based on international standards as well as the most accurate DIgSILENT General Fault Analysis (GFA) method. The following features and options are supported by all implemented fault analysis methods:
Calculation of fault levels at all busbars.
Calculation of short-circuit quantities at a selected busbar or along a defined section of line/cable, including all branch contributions and busbar voltages
Calculation of all symmetrical components as well as phase quantities.
User-definable fault impedance
Provision of specially designed graphs and diagrams including all quantities typically required by the protection engineer
Thermal overloads highlighted on the single line graphic for busbars and cables, with all equipment overloads available in a summary text report
Calculation of Thevenin impedances as seen from the faulty node
Calculation of apparent phase impedances (magnitude and angle) at any location along a transmission line/cable or busbar, for all branches, selected subsets thereof, or 1, 2 or 3 nodes from the faulted node
11.1 Supported Standards IEC 60909 and VDE 0102/0103 PowerFactory provides a strict and complete implementation of the most frequently used standard for component design world-wide; the IEC 60909 and VDE 0102/0103 fault calculation standard, according to the most recently published versions.
Calculation of the initial symmetrical peak current Ik" and short-circuit power Sk", peak short-circuit current ip, symmetrical short-circuit breaking current I b, and thermal equivalent current Ith (IEC 60909-0 2001). Both minimum and maximum short-circuit currents can also be calculated based on network voltage c-factors
Support of all fault types (three-phase, two-phase, two-phase to ground, single-phase to ground)
Calculation of Ik with selectable “Decaying Aperiodic Component”
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Selectable method for calculating the peak short-circuit current in meshed networks
User-definable fault impedance, conductor temperature and c-voltage factor.
Fault calculation can optionally include or exclude motor contribution to the fault current
Provision of specially designed graphs and diagrams required by the protection engineer for protection coordination and design
IEEE 141 / ANSI e 37.5 PowerFactory provides a thorough implementation of the IEEE 141/ANSI e37.5 fault calculation standard according to the latest published version. Special features are:
Transformer tap positions can be included in the fault current calculation
User-defined fault impedance and pre-fault voltage can be included in the fault current calculation
Other Standards G 7 4 and IEC 61363
11.2 Complete Method/Multiple Faults DIgSILENT PowerFactory’s Complete Method is especially designed for protection coordination purposes or for analyzing observed system contingencies. It provides the required algorithms and precision for determining the “true” or “operational” short-circuit currents without considering the simplifications or assumptions typically made in standard fault analysis. In addition to the high precision network model, multiple faults which occur simultaneously in the system or unusual fault conditions such as inter-circuit faults or single-phase interruptions can be analysed.
The Multiple Fault Analysis executes a complete network analysis based on subtransient and transient representations of electrical machines taking into account all specified network devices with their full representation and pre-faulted load conditions.
Combination with IEC60909 principles for the calculation of aperiodic components and peak short-circuit currents
Calculation of peak-break and break-RMS currents
Consideration of a complete multi-wire system representation. Applicable to single-phase or two-phase networks.
Analysis of multiple fault conditions
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Calculation of any asymmetrical, single or multiple fault condition with or without fault impedance, including single- and double-phase line interruptions.
11.3 Fault Analysis Results (all Methods) PowerFactory offers many reporting options, including detailed reporting on all short-circuit levels for all faults, or alternatively, a specific report for a particular fault type. Special protection reports can also be generated to include impedance, current and voltage information.
Display of any variable within the single line graphic, station diagram and Flexible Data Page
Fully flexible filter mechanisms to display objects in colour mode
Detailed analysis reporting, which can list overloaded system elements, unacceptable bus voltages, system islands, out-of-service components, voltage levels, area summaries and more
Detailed text output with pre-defined or user-defined filters and levels
DPL interactivity with all results
Result export to other software applications such as MS-EXCEL or MS-ACCESS
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12 N e t w o r k R e d u c t i o n
12 Network Reduction The typical application of the network reduction tool is a project where a specific network has to be analyzed but cannot be studied independently of a neighbouring network of the same or of a higher or lower voltage level. In this case, one option is to model both networks in detail for the calculation. However, there may be situations in which it is not desirable to perform studies with the complete model; for example when the calculation time would increase significantly, or when the data of the neighbouring network is confidential. In such cases it is good practise to provide a representation of the neighbouring network which contains the interface nodes (connection points) which may be connected by equivalent impedances and voltage sources. The objective of Network Reduction is to calculate the parameters of a reduced AC equivalent of part of a network, as defined by a boundary. This boundary must completely split the network into two parts. The equivalent network is valid for both load flow and short-circuit calculations. ,Following this, a model variation can be optionally created in the PowerFactory database, whereby the full representation of the portion of network that has been reduced is replaced by the equivalent.
12.1 General Features
Flexible definition and maintenance of network boundaries. Various features such as colouring of boundaries and topological checks
Network Reduction can be calculated at any appropriate boundary
Support of Standard Ward (PQ-equivalent), Extended Ward (PV-equivalent) and equivalent loads
Support of short-circuit equivalents for transient, subtransient, peak-make and peak-break currents
The reduced network can be created in a network variation. This allows for simple comparison and swapping between reduced and non-reduced cases.
Robust reduction algorithms based on the sensitivity approach, i.e. reduced network matches for the current operating point as well as for network sensitivities
Implicit result verification feature
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13 V o l t a g e S t ab i l i t y A n a l y s i s
13 Voltage Stability Analysis 13.1 PV Curves PowerFactory supports the calculation of PV curves by applying specifically implemented scripts. These scripts perform the calculation of voltage variations against:
Load variation in a selected area
Load shift across boundaries (keeping the total load constant)
Generator shift across boundaries (keeping the total generation constant)
PV curves can be calculated for a selected set of contingencies. Diagrams are automatically created.
13.2 Q-V Analysis For analyzing the required reactive power reserve at individual busbars, PowerFactory provides scripts for the calculation of Q-V curves.
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14 L o a d F l o w S e n s i t i v i t i e s
14 Load Flow Sensitivities Supplementing PowerFactory’s voltage stability analysis suite is the Sensitivity Analysis tool. It is often required to not only know the critical point of a system, but also how this critical point is affected by changes in system conditions. PowerFactory’s Sensitivity Analysis tool performs a static voltage stability calculation according to the following options:
Sensitivity to a single busbar (calculation of the voltage sensitivities of all busbars and branch flow sensitivities according to variations in power ( P and Q) at the selected busbar).
Option to calculate sensitivities with respect to all busbars simultaneously.
Sensitivity to a transformer tap position change (calculation of the voltage sensitivities of all busbars and branch flow sensitivities according to changes of a transformer/quad booster tap).
Modal analysis - Identification of “weak” and “strong” parts of the network based on modal transformation of the ∂v/∂Q sensitivity matrix. - Eigenvalue calculation on the ∂v/∂Q sensitivity matrix, with a user-defined number of eigenvalues to be calculated. - Results of eigenvalues are displayed (in descending order according to magnitude), and branch/bus sensitivities can be displayed for each mode.
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15 C o n t i n g e n c y A n a l y s i s
15 Contingency Analysis The new Contingency Analysis tool in DIgSILENT PowerFactory has been designed to offer a high degree of flexibility in configuration, calculation methods and reporting options. Single- and multiple- time-phase contingency analyses are available, both of which offer automatic or user-defined contingency creation based on events, and the consideration of controller time constants and thermal (short-term) ratings. Calculation Options for Contingency Analysis:
Support of three calculation methods: - AC load flow calculation - DC load flow calculation - Combined DC/AC calculation; i.e. full DC load flow calculation and automatic recalculation of critical contingencies by AC load flow
Single- and Multiple- Time-Phase calculations. Multiple time-phase contingency analysis facilitates userdefined post-fault actions within discrete time periods.
Generator Effectiveness and Quad Booster Effectiveness calculation: This calculation feature assists the planner in defining appropriate measures for overstressed components in critical contingency cases: During contingency analysis, the possible impact of individual generator re-dispatch or transformer tap changes on overstressed lines is evaluated. Corresponding reports are available that list the generator and quad booster effectiveness on a per-case basis.
Ultimate Performance via Grid Computing: Possibility to perform the contingency analysis calculation in parallel (on multi-core machines and/or clustered PCs)
Management of Contingencies/ Fault Cases:
User-friendly definition of contingencies (n-1, n-2, n-k, busbar) as ‘Fault Cases’ supporting user-defined events to model post-fault actions (re-switching, re-dispatching, tap adjustment, load shedding)
Clustering of ‘Fault Cases’ into ‘Fault Groups’ for efficient data management
Special Operational Libraries to manage ‘Fault Cases’ and ‘Fault Groups’ for future re-use
Automatic creation of contingency cases based on Fault Cases, considering current network topology
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Result File Management:
Recording of results in (sparse) result file; accessible for any kind of export and/or customer-specific post-processing
Predefined and user-definable monitoring lists for recording of results; selection of individual components, component classes and their associated variables to be recorded. Any available calculation result for a standard load flow calculation is accessible during contingency analysis.
User-defined limits for recording of results (thermal loadings, voltage limits, voltage step change)
Reports: A wide range of standard reports is available, facilitating summary views or the presentation of results on a percontingency basis:
Maximum Loadings Report
Loading Violations (per case) Report
Voltage Ranges Report
Voltage Violations (per case) Report
Generator and Quad Booster Effectiveness Report
Other key features:
Tracing Facilities: Use of the new ‘Trace’ function to step through events in a multiple time-phase contingency, while viewing updated results in the single-line graphic
Support of component-wise Short-Term Ratings based on pre-fault loading and post-fault time
Special “Contingency Analysis” toolbar for user-friendly configuration, calculation and reporting
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16 O v e r h e ad L i n e a n d C a b l e P a r a m et e r C a l c u l a t i o n
16 Overhead Line and Cable Parameter Calculation DIgSILENT PowerFactory incorporates the automatic calculation of the electrical parameters of any cable/overhead line configuration starting from layout and geometric characteristics which are typically available in manufacture’s datasheets. The calculation is applicable over a wide range of frequencies and supports the step-up process of highly accurate line and cable models for harmonic analysis, frequency sweep and EMTsimulation among others. The supported options are described below.
16.1 Overhead Line Parameter Calculation
Any combination of line circuits (1-, 2- and 3-ph), neutral conductors and earth wires, with/without automatic reduction of earth wires
A flexible definition of tower types and tower geometries, including conductor sags, allowing a multiple combination of tower geometries and conductor types that avoids entry of redundant data
Circuit-wise, symmetrical and perfect transposition and user-defined phasing for the definition of any non-standard transposition scheme
Solid and tubular conductor types, including sub-conductors for phase circuits and earth wires
Skin effect
Equivalent impedance and admittance matrices in natural, reduced and symmetrical components
16.2 Cable Parameter Calculation
Multi-phase single core and pipe type cable systems
Flexible definition of cable layouts, including conducting, semi-conducting and insulating layers
Compact and hollow core shapes, filling factor for stranded conductors
Consideration of skin effect
Calculation of layer impedances and admittances in natural, reduced and symmetrical components, including sheath and armour reduction, cross-bonding
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17 D i s t r i b u t i o n N e t w o r k A n a l y s i s
17 Distribution Network Analysis 17.1 Feeder Analysis
Feeder Plots: Graphical display feature (Virtual Instrument, VI) to increase transparency in grid loading and voltage profile analysis along the feeder. Displayed result variables are freely configurable. Full interactivity is given via the VI to access all relevant data of the components belonging to the feeder.
Schematic Visualization of Feeder: Automatic generation of single line diagram to visualize components of the feeder with distance/index view.
Feeder Load Scaling: A load flow calculation feature that allows the automatic adjustment of individual bus loads to match a specified total feeder load. The selection of loads which are to participate in the feeder scaling procedure is user-defined. This method allows for complex scaling scenarios with nested and parallel feeders.
17.2 Low-Voltage Network Analysis PowerFactory integrates enhanced features designed especially for the analysis of LV networks. These functions enable the user to:
Define loads in terms of numbers of customers connected to a line
Consider load diversity
Perform a load flow analysis that considers load diversity for calculating maximum voltage drops and maximum branch current
Perform cable reinforcement optimization to either automatically reinforce selected cables, or to provide a report of recommendations
Perform voltage drop and cable loading analysis
Perform statistical calculations of neutral currents caused by unbalanced single-phase loading and load diversity, to represent a realistic network
17.3 Stochastic Load Modelling On the basis of defined ‘customer units’ the user may specify a number of customers connected to a line. Load flow options are provided to define the load per unit customer according to:
Power per customer unit
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Power factor
Coincidence factor for an infinite nu mber of loads (i.e. ‘simultaneity factor’)
In addition, the user may select one of two methods for considering the stochastic nature of loads:
Stochastic evaluation (theoretical approach, also applicable to meshed networks)
Maximum current estimation (application of stochastic rules for estimating maximum branch flow and maximum voltage drops)
The Load Flow with stochastic load modelling then provides maximum currents for each branch component, maximum voltage drops, and minimum voltages at every bus bar.. The usual variables for currents and voltages in this case represent average values of voltages and currents. Losses are calculated based on average values; the maximum circuit loading is calculated using maximum currents.
17.4 Cable Reinforcement Optimization PowerFactory’s Cable Reinforcement Optimization determines the most cost-effective option for upgrading overloaded cables. The objective function is to minimize annual costs for reinforcing lines (i.e. investment, operational costs and insurance fees). Constraints for the optimization are the admissible voltage band and cable loading limits for the planned network.
Optimization along pre-definable feeder
User-definable library of available cable/OHL types with costs that can be used for reinforcement
Consideration of: - Admissible voltage band limits - Maximum voltage drop limit at the end of the feeder - Maximum admissible Cable/OHL overloading
Various plausibility checks for final solution
Calculated results: report of the recommended new cable/overhead types for lines and cost evaluation for the recommended upgrading
Report mode to propose cable/OHL type changes or automatic type replacement
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17 D i s t r i b u t i o n N e t w o r k A n a l y s i s
17.5 Feeder Tools The PowerFactory Feeder Tools comprise a set of tools for radial systems to change voltage levels, phase technology or to optimize phasing from a particular point downwards. Voltage and Phase Technology Change Tool
Automatic change of the voltage level and/or phase technology inside a pre-defined feeder
Automatic replacement of type data (for transformers, lines, loads and motors) according to preconfigurable type mapping tables – including automatic creation of new compatible types if necessary
Auto-Balancing Tool
Automatic balancing of feeders such that voltage unbalance at terminals is minimized
Reconfiguration of phasing of loads, lines, or transformers and combinations thereof
Supports fixed phasing elements
Colouring modes to visualize phase technology before and after change
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18 P r o t e c t i o n F u n c t i o n s
18 Protection Functions The basic functional model library of DIgSILENT PowerFactory’s protection analysis tool has been extended to include additional devices such as CTs, VTs, relays, fuses and more complex protection schemes including userdefined modelling capabilities. Additionally, there are specially designed interactive VIs (Virtual Instruments) for displaying system quantities and, more importantly, for modifying protection settings in the graphical environment. This last feature is especially useful, as coordinated settings between different protection schemes can be modified via the cursor in the graphical environment, following which the settings in both the database and the simulation environment are also updated. All protective devices are fully-functional under steady-state and transient conditions, allowing device response assessment under all possible simulation modes, including load flow calculation, fault analysis, RMS and Instantaneous Values (EMT) simulation. PowerFactory’s main protection features are:
Extensive relay database Accurate steady-state relay checking via short-circuit and load flow ( balanced & unbalanced)
Precise dynamic relay checking with RMS and EMT simulations
Consideration of current transformer saturation
Diagrams for overcurrent and distance coordination:
o
Time-overcurrent diagrams
o
R-X characteristic diagrams
o
Time distance diagrams
Automatic Protection Coordination Wizard for time-overcurrent protection schemes
18.1 Protection Model Library and Functionality The DIgSILENT PowerFactory protection analysis tool contains a comprehensive protection device model library. All relays are modelled for steady-state calculations (short-circuit, load flow), RMS and EMT simulation modes. The definition of relay types is highly flexible via block diagrams. For RMS and EMT simulation purposes, relays may be extended and adopted to cope with user specific requirements via the PowerFactory DSL language The features of the protection model library are listed below. Fuses are represented by their melting curves. It is possible to take minimum and maximum melting curves into account.
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Time-Overcurrent R elays for 1-phase, 3-phase, ground and negative sequence time over-currents. Additionally, the relay characteristics can incorporate the following standards and solution methods:
IEC 255-3, ANSI/IEEE and ANSI/IEEE squared ABB/Westinghouse CO (Mdar) Linear approximation, Hermite-spline approximation Analytical expressions via built-in formula editor and analyzer (DSL)
Instantaneous Overcurrent Relays for 1- phase, 3-phase, ground and negative sequence time over-currents. Directional Relays for overcurrent, power, ground current, and any combination of time and instantaneous overcurrent relays. Additionally, voltage and current polarization is used for the detection of negative and zero sequence components considering also dual polarization. Optional: with voltage memory. Distance Relays for phase, ground and zone distance protection. Provision is available for incorporating overcurrent and under-impedance starting units (U-I or Z) as well as angle under-impedance. Different characteristics are available for distance relay zones including:
MHO, offset MHO
Polygonal, offset polygonal
Tomatoes, lens and circle
R/X Blinders and quadrilateral
Support of various polarizations such as:
Self-polarized
Cross polarized (90ø connection)
Positive, negative sequence polarized
Optional: voltage memory
Zero sequence and parallel line compensation Voltage Relays for under-voltage, instantaneous voltage, voltage balance and unbalance. Additional devices such as: Breaker Fail, Motor Protection, Generator Protection, Differential Protection, Reclosing Relays, Low Voltage Circuit B reakers, and Out-of-Step Relays.
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In addition to these protection functions and relays, DIgSILENT PowerFactory provides further devices and characteristics for more detailed protection system modelling, such as:
Current and voltage transformers that include saturation effects
Conductor, cable damage curves, cable overload curves and inrush peak current modelling
Transformer damage curves (ANSI/IEEE Standard C57.109-1985) and inrush peak current modelling
Motor starting curves, cold and hot stall, in-rush peak current modelling, and any user-defined curves
All protection device models are implemented within the composite model frame environment. This allows users to easily design and implement their own models, by utilizing the graphical user interface for constructing block diagrams.
18.2 Output & Graphical Representation Time-Overcurrent Diagrams -
Overcurrent curve adjustment using drag & drop
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Display of tripping curve tolerances during drag & drop
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User-defined labels
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Tripping times are automatically displayed for calculated currents in time-overcurrent diagrams
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Display of an unlimited number of overcurrent curves in diagrams
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Simple creation and addition of diagrams via single line graphics
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Display of motor starting curves, conductor/cable and transformer damage curves
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Balloon help showing name of relay, etc.
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Double-click on curves to change relay settings
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Additional axis for voltage levels
R-X Characteristic Diagrams -
Display branch impedances with several options Automatic display of calculated impedances
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Adding relays with offset Flexible display of zones (starting zones, etc.)
Time Distance Diagrams -
Different methods for calculating curves: kilometrical or short-circuit sweep method
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Forward and/or reverse diagram
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Selectivity check of distance and overcurrent relays/fuses in same diagram
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Separate overreach zone representation
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Additional axis showing relay locations and busbars/terminals Selectable x-axis scaling (length, impedance, reactance, 1/conductance)
Single Line Diagram -
Colouring of switches according to relay locations, relay tripping times
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Display of relay tripping times in result boxes
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Additional text boxes for relay settings
Relay Setting Report Relay Tripping Report
18.3 Overcurrent-Time Protection The coordination of overcurrent-time protection is performed graphically using the current-time diagram as the basis. Relay settings are modified using drag & drop to move characteristics. Short-circuit currents calculated by the short-circuit command, are shown in the diagram as a vertical line. In addition, the corresponding tripping times of the relays are displayed. Coordination between relays at different voltage levels is available. Therefore, currents are automatically based on the leading voltage level, which can be selected by the user.
18.4 Distance Protection For distance protection coordination, two powerful graphical features are integrated. The first of these features is the R-X diagram for displaying the tripping zone of distance relays and the line impedances. Several relays can be visualized in the same R-X diagram. This can be useful for the comparison of two relays that are located at different ends of the same line. The relay characteristics and the impedance characteristic of the connecting line
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will be shown in the same R-X diagram. Following short-circuit calculations, the measured impedances are visualized with a marker in the shape of a small arrow or cross. From the location of the marker the user can see the tripped zone and its associated tripping time. For dynamic simulation, measured impedances of the relays can be displayed, thereby visualizing the functioning of power swing blocking or out-of-step tripping relays. The second powerful graphical feature is the time-distance diagram, which is used for checking the selectivity between relays along a coordination path. The relays on a coordination path can be displayed in diagrams for forward, reverse or for both directions. Consequently, it is very easy to check the selectivity of the relays along a coordination path. Two different methods for calculation of the tripping curves are provided. These are the kilometric and the short-circuit method.
Kilometric method: The reach of the zones is calculated from the intersection of the given positive sequence impedance of the lines, and the impedance characteristic of the relays.
Short-circuit method: This is the main method for checking the selectivity. Short-circuits (user-defined fault type) are calculated along the coordination path. The tripping times for the time-distance curve are determined using the calculated impedances. The starting signal of a relay is also considered.
A special feature of the distance protection is the consideration of blocking signals or POTT (permissive overreach transfer tripping), PUTT (permissive under-reach transfer tripping), which are also taken into account. In addition to tripping curves of distance relays, the curves of overcurrent relays can be displayed and coordinated in the same diagram using the short-circuit method. Both the kilometric and the short-circuit method consider breaker opening times in the calculation of tripping times. The breaker opening time can be optionally ignored.
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19 D i s t r i b u t i o n N e t w o r k O p t i m i z a t i o n
19 Distribution Network Optimization In order to reduce network unbalance and improve quality of supply, DIgSILENT PowerFactory incorporates features to assist the user in distribution network optimization:
Optimal capacitor placement
Open tie optimization
Cable reinforcement optimization
Feeder tools for voltage/technology change
Auto-balancing to minimize voltage unbalance
19.1 Optimal Capacitor Placement PowerFactory’s Optimal Capacitor Placement determines the optimal locations, types and sizes of capacitors to be installed in radial distribution networks. The economic benefits due to energy loss reduction are weighted against the installation costs of the capacitors while keeping the voltage profile within defined limits. This feature includes:
User-definable library of proposed capacitor candidates together with annual installation costs
Consideration of: - Benefits due to loss reduction - Voltage limits - Maximum total investment costs
Support of load profiles
Calculated results: set of locations where capacitors should be installed, which type of capacitor(s) should be installed at each site, and whether or not a switched capacitor is proposed.
User-friendly presentation of results with fully-integrated post-processing features
19.2 Open Tie Optimization PowerFactory’s Open Tie Optimization finds a loss-minimal switch configuration of the network, which results in a radial topology while maintaining all thermal limits. This feature includes:
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Heuristic algorithm which explores all potential meshes in the grid to evaluate the optimal tie-points to open
Consideration of loading limits
User-definable section of the network where optimal open tie-points should be determined
Report mode to propose switch status changes or automatic switch reconfiguration
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20 Harmonic Analysis Functions The harmonic analysis functionality is ideal for applications in transmission, distribution and industrial networks for filter design, ripple control signal simulation or for the determination of network resonance frequencies. For analyzing the impact of harmonics in power systems, DIgSILENT PowerFactory provides two harmonic analysis functions.
20.1 Harmonic Load Flow The DIgSILENT PowerFactory harmonic load flow features the calculation of harmonic voltage and current distributions based on defined harmonic sources and grid characteristics. It allows the modelling of any userdefined harmonic voltage or current source, both in magnitude and phase including inter-harmonics. The harmonic sources can be located at any busbar in the power system and may be implemented within any network topology. Harmonic current sources can be associated with any load, SVC (TCR injection), rectifier or inverter. Harmonic voltage sources can be modelled using the AC voltage source model or the PWM AC/DC converter model. The built-in rectifier models inject the spectrum of ideal 6-pulse rectifiers if no other injection has been defined. DIgSILENT PowerFactory supports any type of characteristic harmonic, un-characteristic harmonic (even harmonics etc.) and non-integer (inter-) harmonics. Unbalanced harmonic sources (e.g. single-phase rectifiers) are also fully-supported. The analysis of inter-harmonics or unbalanced harmonic sources is based on a complete abc-phase network model. Because of the phase correct representation of harmonic sources and network elements, the superposition of harmonic currents injected by 6-pulse rectifiers (via Y-Y and Y-D transformers leading to a reduction in 5 th, 7th, 17th, 19th etc. harmonic currents) is modelled correctly. DIgSILENT PowerFactory calculates all symmetrical and asymmetrical harmonic indices for currents and voltages, as defined by relevant IEEE standards, including harmonic current indices and harmonic losses, such as:
THD and HD ((Total) Harmonic Distortion)
TAD (Total Arithmetic Distortion)
IT product
Harmonic losses
Active and reactive power at any frequency Total active and reactive power, displacement and power factor
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Network impedances at selected buses
RMS values
Unbalance factors
Integer and non-integer harmonic order values
Flicker Assessment: - Pst, Plt (Short-, and long-term Flicker Disturbance Factors; continuous and switching operation) - Relative voltage change value
Results can be represented:
In the single line diagram (total harmonic indices)
As histograms (frequency domain)
As waveform (transformation into the time domain)
As profile (e.g. THD versus busbars)
The frequency dependent representation of network elements such as lines, cables, two- and three-winding transformers, machines, loads, filter banks etc. for considering skin effects is fully-supported.
20.2 Frequency Sweep The frequency sweep performs a continuous analysis in the frequency domain. The most common application is the calculation of self- and mutual network impedances for identifying the resonance points of the network and for supporting filter design.
All impedances are calculated simultaneously in the same run. Since DIgSILENT PowerFactory uses a variable step-size algorithm, the calculation time of frequency sweeps is very low while the resolution around resonance points remains very high (typically 0.1 Hz).
Frequency sweeps can either be performed with the positive-sequence network model (very fast) or the complete three-phase abc-network model.
Calculation of self- and mutual network impedances
Calculation of voltage amplification factors
Impedance plots may be created in either Bode, Nyquist or magnitude/phase forms.
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In addition to common applications relating to harmonic distortion, PowerFactory’s Frequency Sweep function can also be used for subsynchronous resonance studies. The calculation of damping and undamping torques is supported by special scripts. Network Modelling The skin effect is considered by associating frequency characteristics with line or transformer resistances and inductances. These characteristics can be specified by either setting the parameters of a polynomial expression or by entering the characteristic point by point using tables. DIgSILENT PowerFactory uses cubic splines or hermite polynoms for appropriate interpolation.
Lines are modelled either by approximate PI sections or by the highly-accurate distributed parameter line model that should always be used for long lines or high frequency applications. The skin effect can be included in both line models.
Filters can be specified by either ‘layout’ parameters or ‘design’ parameters. ‘Layout’ parameters are typically the rated reactive power, the resonance frequency and the quality factor. ‘Design’ parameters are the actual R, L, and C values.
In addition to the explicit specification of frequency dependent resistance or inductance via parameter characteristics, overhead lines can be modelled by defining the tower geometry and cables can be modelled by specifying the cable layout. In such cases, frequency dependent effects, such as the skin effect or frequency dependent earth return, are automatically calculated and considered by the model.
20.3 Ripple Control Signals DIgSILENT PowerFactory provides full support for analyzing and dimensioning ripple control systems. Series and parallel coupling of ripple control systems can be modelled including all necessary filter elements.
The level of the ripple control signal in the entire network is calculated and reported in the single line diagram, the output window or the browser.
20.4 Filter Rating DIgSILENT PowerFactory features a special, easy-to-use function for calculating the rating of all components of a filter. All relevant voltages across all components are calculated and made available in the ‘Filter Sizing’ report.
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21 Optimal Power Flow The PowerFactory Optimal Power Flow (OPF) serves as the ideal complement to the existing load flow functions. Where the standard load flow calculates branch flows and busbar voltages based on specified “set points” (active/reactive power generation, generator voltage, transformer tap positions, etc.), the OPF also calculates the “best possible” values for optimizing a user-specified objective function and a number of user-defined constraints. In this way, the OPF adds intelligence and consequently improves efficiency and throughput of power system studies significantly. Building on the load flow calculation, PowerFactory offers two calculation methods:
AC optimization based on a state-of-the-art interior-point algorithm DC optimization based on linear programming using simplex methods, also supporting contingency constrained optimization.
OPF in PowerFactory allows easy configuration of the optimization task via the simple selection of an objective function, controls (i.e. system variables to be optimized), and constraints. The optimal solution for the selected objective function is calculated under the consideration of a number of possible constraints with which the final solution must comply. All controls and constraints can be flexibly-defined on a component level.
21.1 AC Optimization Supported Objective Functions:
Minimization of system losses
Minimization of costs (based on arbitrary (non-linear) cost curves for generators and load tariffs for external grids)
Minimization of load shedding
Control Variables:
Generator active power dispatch
Generator reactive power dispatch
Transformer tap positions
Switchable shunts
Load consumption (for optimal load shedding)
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Supported Constraints:
Branch flow limits (loading)
Voltage limits (min/max) for busbars/terminals
Active power limits of generators
Reactive power limits of generators
Transformer tap changer limits
Adjustable shunt limits Boundary flow limits (min/max limits for active and reactive power flow along any user-definable boundary)
Since the OPF can dispatch the active power of generators considering reserve limits and considering fuel cost minimization (which is based on non-linear fuel cost functions), the PowerFactory OPF is also a highly advanced economic dispatch function.
21.2 DC Optimization The DC Optimization builds on a sensitivity-based linear programming approach. Most notably, it allows a contingency constrained optimization to be carried out for any predefined list of contingency cases. The optimization simultaneously considers all contingency cases, and the solution is globally optimal and guaranteed to be feasible over all contingency cases (i.e. not violating any constraints in any of the contingencies). Supported Objective Functions:
Feasibility check
Minimization of costs (based on arbitrary (non-linear) cost curves for generators and load tariffs for external grids)
Minimization of generator dispatch change, i.e. finding a feasible solution with minimal re-dispatching
Minimization of pre- to post-fault generator dispatch change (available for contingency constrained optimization only), i.e. finding optimal dispatch for the base case and each contingency case such that the change between the base case and each contingency case is minimal
Minimization of pre- to post-fault transformer tap change (available for contingency constrained optimization only), i.e. finding optimal transformer tap settings for the base case and each contingency case such that the change between the base case and each contingency case is minimal
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Control Variables:
Generator active power dispatch - for base case and all contingency cases
Transformer tap positions - for base case and all contingency cases
Load consumption
Supported Constraints:
Branch flow limits (loading) – for base case and all contingency cases Active power limits of generators – for base case and all contingency cases
Transformer tap changer limits – for base case and all contingency cases
Boundary flow limits (min/max limits for active and reactive power flow along any user-definable boundary) – for base case and all contingency cases
Maximum number of tap changes per contingency
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22 Reliability Analysis Reliability calculations are essential for the evaluation and comparison of electrical power systems in terms of both design and operation. Although non-stochastic contingency analyses (i.e. n-1) are able to highlight obviously unacceptable operational events, they cannot rank these events in terms of either frequency or duration. The DIgSILENT PowerFactory Reliability Analysis tool incorporates standard reliability assessment features together with sophisticated modelling techniques that enable all forms of reliability assessment to be carried out. Failure models are defined using mean yearly failure frequency and repair duration data. For lines and cables, this data is entered in per-length terms. Detailed models are available for generators that enable de-rated states to be represented, with maintenance and common mode models also available. Load forecast and growth curves can be imposed via time-varying load characteristics. Load models are additionally available for hard-to-predict industrial situations, and each can be assigned its own interruption cost using one of the following cost functions: cost/customer/interruption, cost/kW/interruption or cost/interruption. All failure and load models can be represented either by the Markov method, where simple mean repair durations are modelled, or by the sophisticated Weibull-Markov method, where repair duration variance is additionally modelled. The Weibull-Markov model also has the unique property that annual interruption cost indices such as load and process (industrial) interruption costs can be calculated both analytically and quickly. Consequently, PowerFactory’s Reliability Analysis tool enables the comparison and justification of alternative investment proposals on a financial basis. The basic calculation method used is analytical state enumeration. This method is very efficient, produces exact results and is flexible for addressing a wide range of reliability calculation problems. The network reliability analysis can be carried out on the basis of a simple connectivity check (primarily intended for distribution networks) or on the basis of AC load flow calculations which consider load curtailments due to overloading or voltage constraints (for bulk power system analysis). The approach combines fast topological analysis for fault clearance, fault isolation and power restoration, with AC load flow and optimization techniques for addressing energy at risk, load transfer and load shedding. Finally, the results of all reliability assessments can be presented in text format, as user-defined graphs, or within the single-line graphics environment.
22.1 Failure Models The failure models for network reliability assessment include:
Failures of lines, cables, transformers, generators/external grids and busbars
Independent second failures ("n-2")
Common mode failures
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Double earth faults
Protection/circuit breaker malfunction
Transient fault model (for momentary interruption indices)
In addition to the above-listed failure models, planned outages such as scheduled maintenance can also be considered. Special failure models can be used by various network components to share failure data. The failure models hold stochastic failure information (mean yearly failure frequency for sustained, transient and earth faults on a per km basis, as well as mean repair durations). PowerFactory’s user-interface allows for both an easy setup, as well as for simple modification of input data for various studies. The Maintenance feature simulates the effects of network reliability under predefined planned outage scenarios. Maintenance of individual network components can be modelled on an hourly basis.
22.2 State Enumeration Based on the network model and the given failure data, the reliability analysis generates and analyses the resulting contingency cases. In addition, the user can model load forecast and growth curves by imposing time-varying load characteristics. PowerFactory has a very efficient handling of the reliability assessment over time with varying load data, through the use of the following techniques:
Clustering of load states in the state enumeration algorithm Analysing load variation correlations, thereby reducing the overall number of load states Using linear approximation techniques to improve performance in the case of large numbers of load states
22.3 Failure Effect Analysis The Failure Effect Analysis (FEA) simulates both the automatic and manual reactions to faults of installed protection and of the system operators during each reliability assessment. The FEA can be checked and finetuned in an interactive way to exactly match the real system and operator reactions. The Failure Effect Analysis comprises:
Automatic fault clearance by protection devices
Automatic or manual fault isolation
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Automatic or manual power restoration by network reconfiguration. This includes sophisticated sectionalizing and strategic power restoration methods that operate in three distinct phases: - Phase 1: Sectionalizing by remote controlled switch devices - Phase 2: Sub-sectionalizing of strategic areas - Phase 3: Full system restoration Sectionalizing supports serial or parallel switch actions (based on station access times).
Overload alleviation by optimized generator re-dispatch, load transfer and load shedding, under consideration of load priorities and the amount of load that is available for shedding.
Under-voltage load-shedding
For classical bulk power system analysis, it is assumed that post-fault overloads may occur. A full AC load flow, incorporating basic generator re-dispatch and automatic tap changing, is used to analyse post-fault system conditions. Additional load transfer and/or load shedding will then be simulated. In cases where it can be assumed that system restoration will not lead to any overloading, the overload alleviation can be omitted and a fast network connectivity analysis is sufficient.
22.4 System Indices and Results PowerFactory’s Network Reliability Assessment calculates all common reliability indices. Among others, the following indices are available: System indices (also available for user-defined feeders, zones, and areas):
SAIFI, System Average Interruption Frequency Index
CAIFI, Customer Average Interruption Frequency Index
SAIDI, System Average Interruption Duration Index
CAIDI, Customer Average Interruption Duration Index
ASIFI, Average System Interruption Frequency Index
ASIDI, Average System Interruption Duration Index
ASAI, Average Service Availability Index
ASUI, Average Service Unavailability Index
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ENS, Energy Not Supplied
AENS, Average Energy Not Supplied
ACCI, Average Customer Curtailment Index
EIC, Expected Interruption Cost
IEAR, Interrupted Energy Assessment Rate
SES, System Energy Shed
LOLE, Loss of Load Expectancy
LOEE, Loss of Energy Expectation
LOLF, Loss of Load Frequency
LOLD, Loss of Load Duration
MAIFI, Momentary Average Interruption Frequency Index
Load Indices:
AID, Average Interruption Duration
ACIF, Average Customer Interruption Frequency
ACIT, Average Customer Interruption Time
LPIT, Load Point Interruption Time
LPIF, Load Point Interruption Frequency
LPENS, Load Point Energy Not Supplied
LPEIC, Load Point Expected Interruption Costs
LPCNS, Load Point Customers Not Supplied
LPPNS, Load Point Power Not Supplied
LPPS, Load Point Power Shed
LPES, Load Point Energy Shed
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LPIC, Load Point Interruption Costs
TCIF, Total Customer Interruption Frequency
TCIT, Total Customer Interruption Time
Busbar Indices:
AID, Average Interruption Duration
LPIF, Yearly Interruption Frequency
LPIT, Yearly Interruption Time
22.5 Special Features The Network Reliability Assessment is fully-integrated into PowerFactory, thus profiting from the extremely flexible data management and data handling for setting up individual studies.
22.5.1 High Flexibilit y Each contingency case is created and analysed based on events (i.e. switch events, load shedding events, generator re-dispatch events). By default, the events are created automatically by the reliability calculation algorithm. This allows the user to analyse, adjust and fine-tune the individual cases in a very flexible manner. The reliability calculation will then consider the user-defined events for the FEA instead of creating them automatically.
22.5.2 Tracing of Individual Cases The user can examine the results of a single fault by running the fault case of interest in the trace mode, a stepby-step analysis that sweeps over the individual actions of the FEA. The switching actions and load shedding/generator dispatch events created by the reliability calculation will then be applied to the network and the results can be viewed and analysed after each time step.
22.5.3 Powerful Output Tools for Result Representation Results can be viewed in a variety of ways:
Formatted reports
Tabular result views (integrated into the PowerFactory Data Manager)
Graphical result representations
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Various colouring modes
22.5.4 Contribution t o Reliability Reliability Indices Indices Post-processing tools allow the calculation of individual components’ contributions to system indices. In this way the user can study the impact of certain network components (such as lines/cables, transformers, etc…) on the overall system indices. Likewise, loads can be grouped into load classes (industrial, agricultural, domestic, etc…) and their contribution to, for example, energy indices can be evaluated.
22.5.5 Development Development of o f Indices Indi ces over Years Years Taking into account the evolution of the network model and the failure data over time, PowerFactory supports the calculation and visualization of the reliability indices over years.
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23 S t a t e E s t i m a t i o n
23 State State Estimation Estimatio n The PowerFactory State Estimator provides an accurate real-time analysis of the full operating system based on the information provided by selectively monitored data, e.g. that of an installed SCADA system. The objective of the state estimator is to assess the generator and load injections in a way such that the resulting load flow solution matches as closely as possible the measured branch flows and busbar voltages. The features of PowerFactory’s State Estimation tool include:
Flexible definition of external measurement devices in the network model supporting the following measurement types: -
Active and reactive power branch flows Branch current (magnitude) Busbar voltage (magnitude) Breaker status Transformer tap position
User-definable selection of system states to be estimated/optimized: estimated/optimized: -
Loads: Active and reactive reactive power demand, demand, or alternatively the scaling factor Generators and static static generators: Active Active and reactive power generation Asynchronous machines: Active power power generation generation Static Var Systems: Reactive Reactive power injection Transformers: Tap positions
High-precision estimation of full system state that minimizes deviations from measurements
Fast-converging non-linear optimization algorithms
Observability check based on a novel sensitivity analysis approach - Detection of unobservable unobservable system system states states - Grouping of unobservable states in equivalence classes - Detection of redundant redundant measurement measurement locations locations
Innovative patch strategies for unobservable areas; usage of automatically created pseudomeasurements
Bad data detection in the loop
Measurement plausibility checks as pre-processing, such as: - Node sum checks checks for active active and reactive reactive power - Check for consistent consistent active power flow flow directions at each each side of branch elements elements - Check for unrealistic unrealistic branch losses and unrealistic branch branch loadings
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- Check for negative negative losses on passive branch branch elements - Check for large large branch flows on open-ended open-ended branch elements elements
Statistical report and colouring modes to visualize measurement qualities
Fully featured, large scale AC/DC system representation
The PowerFactory State Estimator is supporting a variety of communication options such as OPC (OLE for Process Control) or Shared Memory Interface for implementing data interchange with any kind of SCADA system.
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24 D y n a m i c M o d e l l i n g F l e x i b i l i t y ( D SL )
24 Dynamic Modelling Flexibility (DSL) DIgSILENT PowerFactory features unmet flexibility in implementing user-specific modelling needs for stability analysis (RMS & EMT) purposes. The fundamental level of flexibility level is provided by graphical object wiring diagrams called Composite Model Frames . They provide a user-friendly means to configure functional block relations (Slots ) using object signal connections.
Any existing PowerFactory object can be plugged into a Composite Model Frame Slot.
Frames can be lumped and nested to any degree of complexity.
Hundreds of objects such as power system components (e.g. busbars, generators, lines, transformers, motors, voltage controllers, prime movers, power system stabilizers, motor driver machines, relays, relay components, CTs, VTs, measurement files, FFT devices, real time clock, RMS signal transducer, parameter identifiers, controllers, power plant control components, A/D converter, RPC links), result files or display objects are at the user’s disposal.
In cases where additional functions are required which are not included in the built-in model- and macros-library, these can be created using the DSL language.
DIgSILENT Simulation Language (DS L) main features:
Flexible definition of macros, functions and models, which is not limited to the use of predefined blocks of a block-oriented simulation language (BOSL).
DSL is a C ontinuous S ystem S imulation L anguage (CSSL) featuring a complete syntactical description of continuous linear and nonlinear as well as digital systems. DSL is dedicated to common control and logic diagrams; it is a non-procedural language as the sequence of elements can be chosen arbitrarily.
DSL syntax elements are algebraic and differential equations as well as intrinsic functions such as signal limiting blocks, tables and curve approximation, delay, interrupt procedures, logical blocks, etc.
Basic control elements such as PID, PTn or even complete physical subsystems such as HVDC valve groups or excitation systems can be defined as macros or high-level functions.
Automatic calculation of initial conditions utilizing various iterative procedures for initializing complex, nonlinear equations of coupled systems.
Provision of various formal procedures for error detection a nd testing purposes, e.g. algebraic loop detection, reporting of unused and undefined variables and missing initial conditions.
DSL models are considered by the PowerFactory EMT/RMS simulation. Multi-level modelling is provided for the different steady-state descriptions and transient time domains (short/mid-term, long-term and electromagnetic).
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24 D y n a m i c M o d e l l i n g F l e x i b i l i t y ( D SL )
DSL models can be created by drawing a “block diagram”. Any “block” may contain another DSL model, a macro or any sequence of DSL syntax. The DSL-editor will then generate the DSL description automatically and will also provide direct model testing functions such as eigenvalue analysis or stepresponse tests of the complete DSL model or of sub-models only.
DSL Implementation The DIgSILENT Simulation Language (DSL) is fully-integrated into the PowerFactory program kernel via the graphical interface.
Signals: Specific input- and output signals defined for all PowerFactory objects as well as any variable defined in a DSL model can be accessed in their corresponding read- or write- mode.
Interrupts: Conditions derived by DSL models can cause interrupts to be sent to the simulation kernel where they are scheduled within the event queue.
Output and Monitoring: Conditions may trigger an output to be displayed in the output window and stored in the simulation log file.
Advanced Features
DSL models feature the direct interaction with external processes such as DAQ interfaces, SIMULINK modules or other software systems via time-synchronized communication channels
Support of OPC Client and shared memory communication
Procedures written in C++ code can be directly linked via appropriate interface mechanisms
Encryption of DSL models to conceal confidential data
User-specific C++ Code The user has two options for combining the PowerFactory DSL modelling approach with externally developed C++ code. 1.
User-defined intrinsic functions can be linked via external DLL for extending the already broad range of DSL standard intrinsic functions such as: “abs”, “sin”, “cos”, “exp”, etc. and DSL special functions such as “lapprox”, “lim”, “limstate”, “delay”, “picdro”, “time”, “file”, “flipflop”, etc. User defined intrinsic functions are to be linked to PowerFactory via the DLL “digexfun”.
2.
Complete user-defined models of any modelling level, linked via the DLL “digexdyn” is supported for any discrete system. Typical applications are digital control systems which are executed via clocksynchronized calls, simulation models being implemented via difference equations, or models which incl. their state variables and integration algorithms internally.
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25 Power System Dynamics 25.1 General Capabilities PowerFactory’s high precision time-domain RMS- and EMT -simulation kernel, complemented by a comprehensive model library and a user-definable, graphical modelling function (DIgSILENT Simulation Language (DSL)), provides a flexible and powerful platform for solving both, system stability and electromagnetic simulation tasks. Grid Modelling Capabilities
Simulation of radial and meshed 1-, 2-, 3- and 4-phase AC and/or DC systems
Modelling validity ranging from low-voltage (LV) up to ultra high-voltage (UHV)
Distributed generation modelling and simulation capabilities
High precision wind power models of various technologies
Balanced and unbalanced grid loading conditions
Simulation of railway systems
Advanced Simulation Models
High precision models for both solid and salient pole synchronous machines, asynchronous machine model including a doubly-fed induction machine model with integrated or externally connected PWM converter. VSD (Variable Speed Drives) systems, PWM converter and other power electronic elements such as the softstarter, inverter and rectifier. In general, all available power system elements are also supported for stability simulations.
General load models where load inertia, bus voltage and frequency dependence is represented; a special lumped load model to accurately represent feeders containing a high percentage of motor load (RMS only). The capability of modelling motor stall effects is included, and was developed on the basis of comprehensive system tests.
Generic wind turbine models with doubly-fed induction generator, direct driven synchronous generator and asynchronous generator with static compensation (STATCOM).
Manufacturer-specific high-precision wind turbine models are available upon request.
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Large library of IEEE controller models covering prime movers, automatic voltage regulators (AVR) and power system stabilizers (PSS).
Support of the comprehensive DIgSILENT Protection Library in stability mode.
RMS Grid Representation Based on a converged load flow, the calculation of initial conditions is carried out prior to the start of a dynamic RMS- or EMT-simulation offering the following grid representation options: RMS simulation only
Positive sequence only - the classical RMS representation for stability studies
RMS and EMT simulation
a-b-c phase RMS representation supporting unbalanced grid loading initialized by a balanced or unbalanced load flow, featuring precise definition of any unbalanced grid fault condition including single- and double-phase line interruptions. This system representation mode avoids tedious handcalculations of equivalent fault impedance and allows access to any a-b-c phase quantity for plotting or precise modelling purposes (e.g. protection devices).
RMS Simulation Algorithms
Highly accurate, fixed or variable step-size integration technique for solving AC and DC network load flow and dynamic model equations. This is combined with a non-linear electromechanical model representation to enable a high degree of solution accuracy, algorithmic stability and time range validity. A-stable simulation algorithm for the efficient handling of stiff systems. This is applicable to all or any individually selected model featuring error-controlled automatic step-size adaptation, ranging from milliseconds up to minutes or even hours, including precise handling of interrupts and discontinuities.
EMT Simulation Algorithms
The calculation of initial conditions is carried out prior to the EMT simulation, and is based on a solved load flow (symmetrical or asymmetrical). Consequently, there is no need for saving steady state conditions being reached after transients are damped out aiming in simulation re-starting under steady state conditions.
Special numerical integration methods have been implemented in DIgSILENT PowerFactory in order to avoid numerical oscillations caused by switching devices and other n on-linear characteristics.
Highly accurate, fixed or variable step-size integration technique for solving AC and DC network transients and dynamic model equations. This is combined with a non-linear electromechanical model representation to enable a high degree of solution accuracy, algorithmic stability and time range validity.
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Faults and Interrupt Handling
The user can interrupt the simulation at any time, either manually, by a scheduled interrupt time or automatically via interrupt conditions. When the simulation is interrupted, most PowerFactory commands such as displaying or printing power flow results, checking the bus voltages, calculating eigenvalues or analyzing the controller status, etc., can be executed.
By activating predefined fault types, or by accessing and modifying PowerFactory variables, any type of fault can be implemented. Typical faults are: - Tripping of any power system element such lines, transformers, feeder loads or generators; - Application and clearing of faults at substations or along lines; - Opening and closing of circuit breakers – e.g. simulating load shedding, shunt switching, starting/tripping of synchronous and asynchronous machines, or when simulating the synchronization of isolated areas via synchro-check relays; - Introduction of “Parameter Change Events” featuring the modification of any built-in and DSL model parameter; - Definition and introduction of inter-circuit events; - Generation of message- and outage-events; - Modification of integration step sizes; - Event-driven modification of variables and signals either manually, via DSL models or by reference to external measurement files.
Simulation Output Processing
Any PowerFactory variable, or any quantity identified in the transmission network, built-in dynamic models or DSL models, may be selected for simulation observation or for later plotting within x/t or x/y diagrams or any other VI (Virtual Instrument) provided. In addition to these variables, the DSL algebraic expression interpreter and logical expression evaluator can be applied to generate further signals or any user-defined quantity.
Plotting files may be retained for re-plotting in comparison with subsequent runs.
Output window log of all simulation events, providing a detailed analysis of manually entered or automatically initiated events.
Simulation results are stored in a proprietary binary PowerFactory file format which can be directly converted into COMTRADE files.
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Special PowerFactory Stability Simulation Features
1-click simulation utilizing PowerFactory project and study case definition
Real-time simulation mode with user-defined real-time synchronisation periods (RMS only)
Parallel and sequential synchronization for integrated simulation, e.g. for simulation certain grid sections in RMS mode whilst others are simulated in EMT mode.
Real-time inter-process signal communication via OPC link
A/D and D/A interfacing capabilities (e.g. hardware-in-the-loop simulation)
25.2 Stability Analysis Functions 25.2.1 RMS Simulation with a-b-c Phase Representation The a-b-c phase, steady-state component representation of the power system, features the fundamental frequency analysis of any asymmetrical grid operation condition.
Initialization via balanced or unbalanced power flow
Simulation of unbalanced loading conditions in 1-, 2- and 3-phase AC and DC systems
Simulation of any number and combination of unbalanced faults including single- and double-phase line interruptions
The a-b-c phase system representation mode avoids tedious hand-calculations of equivalent fault impedance
It also allows for accessing any a-b-c phase quantity for plotting or precise modelling purposes (e.g. protection devices)
25.2.2 Long-term Stability In many cases stability calculations must be run for long periods thus taking into account effects of slower control systems such as boiler control, network exchange control or transformer tap-changer control. Other applications are varying loads or applications of wind power where the impact of wind speed fluctuations must be analyzed. In such cases, short-term and mid-term dynamics have already reached steady-state but slower transients are still being observed.
Long-term stability simulations based on adaptive step-size algorithms with accuracy-controlled step-size adaptation ranging from milliseconds to several minutes without any decrease in precision or even manipulation of transient behaviour.
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A-stable simulation algorithm which fully covers fast transients as well as slow, semi steady-state dynamics with high-precision event handling (stiff systems).
Typical Applications
Voltage stability analysis considering effects of load variations, tap-changer control and reactive power limits
Long-term flicker analysis in cases such as fluctuating renewable generation or varying loads
Secondary control analysis and optimization
25.3 Transient Motor Starting PowerFactory’s Transient Motor Starting functionality analyses motor starting scenarios where the effect of a motor starting on the grid frequency is negligible. In such situations, the typical questions to be answered are:
What is the maximum voltage sag? (This is typically not the initial voltage sag at t=0)
Will the motor be able to be started against the load torque?
What is the time required to reach nominal speed?
How will the supply grid be loaded and which starting options should be considered?
The Transient Motor Starting function makes use of the PowerFactory stability module by providing a preconfigured shortcut for easy-to-use motor starting analysis. The motor starting is initiated by selecting the respective motors within the single line diagram and initiating the motor starting calculation.
A complete symmetrical or asymmetrical AC/DC load flow will be computed prior to the motor starting event; pre-selected and pre-configured VIs are automatically created and scaled with full flexibility for user-configuration.
Consideration of high-precision, complex motor models with built-in parameter estimation. A comprehensive library of low voltage, medium voltage and high voltage motors is provided.
Typical motors supported are: single- and double cage asynchronous machines, squirrel and slip-ring motors, double-fed induction machine, synchronous motors.
Access to the model library for built-in motor driven machine characteristics (torque-speed characteristics) with flexible user-modelling support. Support of various starting methods such as direct start, star-delta starting, variable rotor resistor, thyristor softstarter, transformer softstarter, variable speed drives, etc.; start from any rotational speed.
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Full flexibility in considering starting sequences.
Full representation of generators with exciter/AVR model support on the basis of built-in models (e.g. IEEE models) as well as user-defined models utilising the DSL approach; consideration of protection devices such as under-voltage protection, over-current protection, automatic restarting relays (EMR) or transformer OLTC.
25.4 Electromagnetic Transients (EMT) DIgSILENT PowerFactory provides an EMT simulation kernel for solving power system transient problems such as lightning, switching and temporary over-voltages, ferro-resonance effects or sub-synchronous resonance problems. Together with a comprehensive model library and a graphical, user-definable modelling system (DIgSILENT Simulation Language (DSL)), it provides an extremely flexible and powerful platform for solving power system electromagnetic transient problems. Any combination of meshed 1-, 2-, and 3-phase AC and/or DC systems can be represented and solved simultaneously, from HV transmission systems, down to residential and industrial loads at LV distribution levels. Standard built-in models include:
Lumped and distributed parameter line/cable models; constant and frequency-dependent.
2- and 3-winding transformers and autotransformers for 1-, 2- or 3-phase systems, including stray capacitances, tap dependent impedance and saturation effects. Flexible definition of non-linear magnetizing reactance: two-slope, polynomial, flux-current values
Passive RLC branches, capacitor banks and filters of multiple layouts
Surge arresters, including calculation of energy absorption
Voltage and current, AC-, DC- sources Impulse sources (to be modelled via DSL) VT, CT and PT models, including saturation effects
Series capacitor, including MOV and bypass switches
Discrete power electronic components such as diodes, thyristors, IGBTs
HVDC valve groups (6- and 12-pulse Graetz bridge configurations) and other FACTS devices such as SVCs, UPFCs, TCSCs and STATCOMs
Synchronous and asynchronous machine, doubly-fed induction generator
Circuit breaker models (to be modelled via DSL)
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Stochastic switching (procedures to be implemented via DPL scripts).
The package provides a powerful user-friendly graphical environment for the evaluation of simulation results characterized by:
User-customizable plots for waveform visualisation, including filtering options, scaling, etc.
Calculation of Fast Fourier Transform (FFT)
Export capability to COMTRADE-Files, spreadsheet-format, CSV-files, WMF-files, etc.
25.5 Dynamic System Parameter Identification Built-in system identification and general optimization procedures provide an easy and accurate method to perform model parameter identification on the basis of system tests and field measurements. The PowerFactory Parameter Identification tool is suitable for parameter estimation of multi-input multi-output (MIMO) systems, which are described by any type of nonlinear DSL model. The identification procedure is fully integrated into the graphical frame definition and block diagram, and also features parameter estimation for integrated models (such as loads or generators) which form part of a power system model. The optimization procedures provided are highly generic and can also be used for optimally tuning parameters such as PSS settings according to defined model response functions.
25.6 PowerFactory Real-Time Simulators The PowerFactory stability simulation (RMS mode) can be optionally executed in real-time offering a number of additional applications. The Real-Time Training Simulator is integrated into existing SCADA systems to:
train operator personnel to precisely and efficiently respond to abnormal system conditions, thereby preventing further system deterioration;
locate and investigate insecure operating conditions and calculate required security margins;
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facilitate the operator in understanding phenomena such as basic system dynamics, system control and stability and protection, which are typically too fast for the operator to observe
A report of a typical Real-Time Simulator application can be found at: http://www.digsilent.de/?p=Company/Latest_News&id=2004-06-20_1 Hardware-in-the-Loop Testing is often required to develop, analyse and tune control systems for any kind of turbine, generator or superimposed control systems such as a “Smart Grid Controller”. Applications include:
Real-time simulation of typical grids, test systems or substations including generators, their control systems and associated protection.
Communication with existing hardware such as controllers or relays via OPC, shared memory or A/D systems.
Simulation of grid disturbance scenarios, sensitivity analysis on grid operating conditions, tuning optimization of controllers, investigation of control structures, etc.
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26 Small Signal Stability The DIgSILENT PowerFactory modal analysis tool features small signal analysis of a dynamic multi-machine system. System representation is identical to the time domain model. It covers all network components such as generators, motors, loads, SVS, FACTS, or any other component used in the system representation, including controllers and power plant models. Analysis of eigenvalues and eigenvectors is appropriate for applications such as low-frequency oscillatory stability studies, PSS tuning, determination of interconnection options and its basic characteritics, and is a natural complement to the time domain simulation environment. It also allows for the computation of modal sensitivities with respect to generator or power plant controllers, load characteristics, reactive compensation or any other dynamically-modelled equipment. PowerFactory’s Eigenvalue Analysis is very user-friendly, requiring minimal configuration of the command. Its calculation steps are as follows:
Based on a converged and adjusted power flow, the modal analysis starts with the calculation of the system initial conditions. Alternatively, any interrupted status of a time domain simulation could be used as the initial condition.
The system A-matrix is constructed automatically for the complete system (including generators, general loads, predefined system plant and controller models as well as DSL devices).
System and model linearization - including user-defined models - is performed by iterative procedures. Limiting devices are disabled automatically. The representation of the network model is equivalent to the simulation model, allowing a direct comparison/validation between time domain simulations and modal analysis results.
Support of QR-algorithm as well as the Arnoldi-Lanczos method. o
Calculation of all eigenvalues based on QR algorithm
o
Selective eigenvalue calculation:
computation of a certain part of the eigenvalue spectrum: calculation of a userdefinable number of (closest) eigenvalues around a complex reference point based on the Arnoldi-Lanczos method recommended as a fast approach for higher order systems for which calculation of all eigenvalues by QR algorithm is too time-consuming
Calculation results include eigenvalues (together with oscillation information such as damped frequency, damping, damping ratio, damping time constant, etc) and left and right eigenvectors. From
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eigenvectors, the individual machines’ controllability, observability, and participation factors are derived with respect to each mode.
Powerful post-processing tools for result visualization o
Tabular result representation of:
o
Visualization of calculated eigenvalues in the Gaussian plane
Various filter and scaling options
Automatic determination of stability border, highlighting of stable/unstable eigenvalues Plot has interactive features that facilitate detailed analysis of individual modes; convenient creation of phasor plots/bar diagrams for each mode
Mode Bar Plot
o
Eigenvectors (individual controllability, observability, participation of individual machines for any selected mode)
Eigenvalue Plot
o
Eigenvalues (including all oscillation information such as damped frequency, damping, damping ratio, damping time constant, etc)
Bar diagram visualization of controllability, observability and participation factors of individual machines for a given mode Various filter options (e.g. restriction to minimum participation, and/or individual generators)
Mode Phasor Plot
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27 PowerFactory Interfaces PowerFactory offers a number of mechanisms and options for interfacing with external applications such as GIS and SCADA, or for a complete integration and background execution in “Engine Mode”. Depending on the application, the user may choose from the options described below.
27.1 DGS Interface DGS (DIgS ILENT-GIS-SCADA) is PowerFactory’s standard bi-directional interface specifically designed for bulk data exchange with other applications such as GIS and SCADA, and, for example, for exporting calculation results to produce Crystal Reports, or to interchange data with any other power system software. DGS does not support the exchange of PowerFactory execution commands.
Available for PowerFactory Interactive Window Mode and PowerFactory Engine Mode
User-specific definition of objects and object parameters
Supported objects: elements, types and libraries, graphics and results
Import and export of complete network models
Import and export of incremental data for updating existing models
Databases supported: Oracle, MS-SQL and ODBC System DSN
File formats supported: ASCII Text (CSV), XML, MS-Excel and MS Access
27.2 OPC Interface OPC (OLE for Process Control) is an asynchronous communication and data exchange mechanism used in process interaction and is widely applied in SCADA and control systems. PowerFactory OPC-implementation assumes that the PowerFactory software is executed as an OPC-Client while the OPC Server is controlled via the external source. OPC server libraries are available from various manufacturers. An example of a freeware OPC-Server is that available from Matrikon (“MatrikonOPC Simulation Server”).
Supported of the PowerFactory Engine Mode
OPC-Client/Server exchange of any PowerFactory object parameter as well as any signal
PowerFactory listening mode to receive any data or signal from a registered OPC Server
PowerFactory sending mode to write back any data or signal to a registered OPC Server
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Pow erFactory Engine (Client)
OPC Application (Server) OPC items (object parameters, object and model
Selected values *)
signals - e.g. measurem ents or controller output signals) are managed by the OPC Server. Changes to these values are propagated to connected clients.
Executed in the background, the Pow erFactory Engine listens for signals sent by the OPC Server.
*) communication is asynchronous, so neither the server nor the client waits for a response
Received values are processed as PowerFactory input signals or parameters and considered by running calculations in an executio n loop. For example:
Load Flow or online State Estimation
Time Domain Simulation
Optionally, parameters or any output signal can be associated with OPC items w hich are sent back to the OPC Server.
selected values returned *)
Receives modified paramet ers and signals and immediately propagates them to all subscribed clients
27.3 Shared Memory Interface DIgSILENT PowerFactory provides a high-speed shared memory communication interface that allows other applications to use PowerFactory as a calculation engine.
Supported of the PowerFactory Engine Mode Via the shared memory, modification of any object parameter, initiation of command execution and access to any calculation result is supported.
Option to trigger an update of the PowerFactory database
The communication is based on a request/response interaction. PowerFactory acts as a server that waits for requests. Each request must contain a command and can optionally contain input data and result definitions.
The synchronization between client and server is based on OS events.
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The PowerFactory shared memory request / response interaction
Request
Object data contained? Copy data to PowerFactory objects Execute command
Result definitions contained? Fetch results from PowerFactory objects and include them in reponse Response
The PowerFactory shared memory client/server interaction
Shared Memory Application (Client)
PowerFactory (Server)
Writes data into shared mem ory (request):
Commands
Input data (optional)
Result definitions (optional)
event _REQUEST
Processes request:
Reads input data from shared memory
Executes commands
Writes result string to shared memory
Writes object data results into shared memory (optional)
Reads data from shared memory (response):
Status
Result data (optional)
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28 Interfacing PowerFactory Interfacing and integrating power system software with other applications such as GIS (Graphical Information Systems) and SCADA (Supervisory Control And Data Acquisition) systems is an important requirement. Utilizing the implemented DGS, OLE and Shared Memory interfacing techniques, DIgSILENT PowerFactory features great flexibility in supporting any level of interfacing and integration needs. The following sections summarize some typical examples.
28.1 PowerFactory - GIS integration PowerFactory – GIS integration is preferably implemented via the DGS-interface. As object and parameter definitions at the GIS side usually reflect user-specific needs, standardized interfacing is only provided when a standard application module/standard process model provided by the respective GIS manufacturer is in use. As soon as user-specific object and parameter definitions are applied, individual object mapping will be required. Implement ation Options
Unidirectional GIS to PowerFactory data transfer via DGS format definitions (CSV or ODBC)
Bidirectional data transfer (e.g. via the PowerFactory shared memory interface) when running PowerFactory in “Engine Mode” or “Hybrid Mode”, which features full integration of PowerFactory analysis functions and additional graphic display options in the GIS system
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Characteristics
Incremental data exchange utilizing PowerFactory’s user accounting, project management and merge tools featuring GIS -to -PowerFactory team working
Combines and merges several data sources via PowerFactory’s data handling capabilities, thereby avoiding any middleware requirement
Application Aspects
Sharing of data sources, thereby avoiding duplication of data entry and maintenance
Utilizing key capabilities of PowerFactory and GIS while sharing data
Amalgamating data from various sources at the PowerFactory level
As most applications require the merging of additional data such as customer load consumption, dispersed generation infeeds and SCADA readings, PowerFactory – GIS integration is often handled as a project implemented via clearly defined specification of data sources and overall workflow.
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28.2 PowerFactory - SCADA integration Interfacing with SCADA gives direct access to dynamic and/or static SCADA data, allowing both real-time system analysis and incident analysis from previous snapshots. As DIgSILENT PowerFactory already integrates topology processing, interfacing can be done on a point-to-point basis using foreign database keys. In addition to the option of exchanging data between SCADA applications and PowerFactory, a full SCADA integration of the PowerFactory engine is supported when using PowerFactory OPC link features. Typical applications are operators’ access to calculations such as load flow, contingency analysis, etc., including real-time simulation for operator training.
Support of PowerFactory Engine Mode and Hybrid Mode
SCADA – PowerFactory communication via OPC, executing PowerFactory as a client
Direct 1-to-1 relation between SCADA network objects due to full substation topology support of PowerFactory
Utilization of SCADA manufacturer’s state estimation functions, or, if not present, PowerFactory’s advanced state estimation features
Operator’s access to all PowerFactory functions such as load flow, contingency analysis, optimal power flow, spinning reserve allocation
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28.3 PowerFactory - Simulation Interface (SIMULINK, etc.) Although PowerFactory offers great flexibility in controller modelling, some applications may require special control toolboxes from the Matlab/SIMULINK software package. The PowerFactory – Matlab/SIMULINK interface is a flexible and fully synchronized link for distributed simulation of linked models. The bi-directional communication link is easily implemented via the PowerFactory Frame and Slot technique with a built-in RPC interface block for Matlab/SIMULINK. A typical application example might be the simulation of a large network with a number of conventionally controlled generation units together with a fuzzy-controller implemented at a specific plant.
28.4 PowerFactory - A/D Signal Interfacing Capability PowerFactory’s Frame and Slot technique utilizing the real-time capabilities of built-in blocks for data acquisition has become the basis for the PowerFactory Monitoring system (PFM). The portable or cabinet-mounted Control and Monitoring Units (CMU) along with different types of high precision Signal Units (SU), is featuring the configuration of highly-flexible plant measurement and grid performance analysis systems. Typical application aspects of the PowerFactory Monitor are system tests for simulation model validation, supervision of grid connection conditions, load parameter identification, fault recording, power quality observation analysis or system stability supervision. Due to the superior flexibility in software setup, there is almost no limit in defining measurement and test applications including closed-loop operation with A/D-interfaced controllers, relays or other simulators.
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29 PowerFactory Installation Options 29.1 PowerFactory Workstation License Pow erFactory Workstation License is a standalone solution which is shipped with a free single-user database and is preferably installed locally, on the user’s hardware. This is the option with the fastest performance as database access is directly managed via fast local hard disk I/O, thereby avoiding any LAN traffic.
Typical Single-User Workstation I nstallation with local single-user database
Although it is technically possible to store the PowerFactory database on any network drive, this is not recommended as it requires high-speed LAN capabilities and might exhibit less reliability regarding database integrity when the LAN connection is unexpectedly interrupted.
Typical Single-User Workstation Installation with remote single-user database
Multiple Single-User Licenses DIgSILENT PowerFactory software offers a number of licensing mechanisms. The Workstation License is a Single-User License and is operated via a local USB port hardlock. The hardlock is programmed to include those functions licensed to the user. The locally attached hardlock is only accessible by the locally installed Workstation License.
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Typical Typical m ultiple Single-User Workstation Installation
If you have purchased several Workstation Licenses, the USB hardlock installation is required on all computers where the Workstation License is to be used. Of course, if PowerFactory is installed on more computers than there are USB hardlocks available, only those installations can be used simultaneously where the USB hardlock is plugged-in at that point in time.
29.2 PowerFa PowerFacto ctory ry Se Server rver License Pow erFactory Server License License comes with additional features which are not available with the PowerFactory Workstation license: 1.
Provision of a License Server which can be installed centrally managing any independent number of licensed functions. The License Server comes with only one single USB hardlock holding all licensed functions. The License Server must be accessible for all PowerFactory installations via a network IPaddress.
2.
Support of multi-user database operation, featuring the simultaneous access of all connected users to a single database. The Server License comes with database drivers for both databases; MS-SQL and ORACLE (the database servers themselves are not included).
3.
The Server License can be executed in a Client-Server (Application Server) environment such as MS Sever 2003/2005 or CITRIX, which has the advantage of centralized software installation and maintenance – a typical requirement of modern IT infrastructures.
Multi-User License via License Server The Multi-User License Server gives more flexibility than the single USB hardlock (holding all licenses). This solution provides a license server which is to be installed as an MS Windows Service on any computer in a network that is accessible from the users’ computers via an IP address. This computer could be one of the users’ computers but is recommended to be a separate computer located in a secured room. Upon login, the PowerFactory software on the user’s computer connects to the license server via a LAN to access the license. The license server administrator assigns certain PowerFactory functions to each user when the login procedure is executed. This facilitates the purchase of the optimal number of licenses depending on users’ needs.
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Typical Typical M ulti-User installation with License Server
An optional feature of the Multi-User License Server is the Floating License which allows the temporary transfer of a user license from the license server to a local PC. This option is typically required when a user is travelling with his/her laptop, thereby preventing him/her from accessing the license server. When downloading the floating license to a local machine, the license will disappear from the license server and will move to the local PC until the user reconnects to the license server. The floating license is time-limited and, if not reconnected to the license server, will automatically “fly back” to the license server after a defined time.
Typical Multi-User installatio n with License Server and Floating License Option
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Note:
A clear advantage of the the License License Server is its ability to host a different number of licenses for certain functions. This allows a more economical solution which considers the simultaneity of users. The allocation of functions is made upon user login and not upon the execution of a certain PowerFactory command. This philosophy is based on the notion that upon successful login and allocation of functions, those functions should be available to the user throughout the entire PowerFactory session.
Multi-User Database Centralized data handling is supported by a multi-user database featuring the simultaneous access of all connected users to a single data source. Currently, database drivers for MS-SQL and ORACLE are available. This execution option is designed for PowerFactory installations with a large number of users requiring access to the same project data and, who would benefit from the PowerFactory team-working tools such as Master Project management, Project Versioning, Project Deriving along with Project Compare- and Merge tools, which make concurrent model building and data entry very easy.
Typical Typical Multi-User installation w ith License Server and Multi-User Database
In the configuration shown above, the execution of the PowerFactory software will still take place on the user’s local PC while the multi-user database resides on a special high-speed database server.
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Application Server A further step often required in large companies with tens or hundreds of users is the centralized installation and execution of the PowerFactory software, the database and the License Server. This Application Server installation is currently supported for MS Server 2003/8 and other server add-ons such as CITRIX. The figure below shows a typical example of such a centralized installation environment.
Typical Application Server Installation w ith a multi-user database
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29.3 License Overview Pow erFactory License and Installation Options
Local Installation
Workstation
Server
Educational &
Student / Private
License
License
Research License
Use License
[X]
[X]
[X]
[X]
Application Server Installation
[X ]
Local Hardlock
[X]
[X]
License Server
[X]
Floating License (optional)
[X ]
Local Single-User Database
[X]
Central Multi-User Database
[X]
[X] [X]
[X]
[X ]
29.4 Installation Requirements PowerFactory requires no special hardware or additional software to guarantee good performance. However, taking into account that solving power system analysis tasks is far beyond standard office applications, the following hardware is recommended: Workstation Licenses:
17-23” monitor with min. 1280x1024 pixel resolution Intel/AMD CPU with 2.0 GHz or higher 1 GB available hard disk space (*) 0.5 -3 GB main memory available for the PowerFactory process
(**)
(*)
Required hard disk space will heavily depend on the number of projects handled, number of objects (e.g. size of the network modelled), number of scenarios, etc. Total disk space requirements are therefore determined individually. (**)
The required main memory capacity will heavily depend on the network size and the type of calculations being performed. A typical memory requirement would be between 0.5-1.0 GB exclusively for executing PowerFactory unbalanced load flow, fault analysis and stability for a 5000-bus system. Supported operating systems are Windows 2000, Windows XP, Windows Vista and Windows 7. Application Server:
Application Server hardware requirements are similar to those defined for workstation installations, taking into account that main memory requirements will be duplicated according to the number of simultaneous users. In addition, the number of CPUs is correlated with the number of simultaneous users. Supported operating systems are MS Windows Server 2003/8 and CITRIX. Multi-User database support is available for MS SQL 2005/2008 and Oracle Server 10.x and 11.x with Client 11.1.
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30 P o w e r F a c t o r y F u n c t i o n D e f i n i t i o n s a n d P r i c e s
30 PowerFactory Function Definitions and Prices 30.1 PowerFactory Function Definitions PowerFactory function definitions refer to the latest issue of PowerFactory V14 Product Information to specify the content of the PowerFactory software delivery.
Item 1
Pow erFactory V14.0 Functions PowerFactory Base Package
V14 Product Information Section Reference Included:
Sections 3-17 Section 27.1
Not Included: Section 7.1: PSS/E export, CIM Import/Export 2
Protection Functions (Overcurrent-time & Distance)
Included:
Section 18
3
Overcurrent-Time Protection
Included:
Section 18.1-18.3 and 18.5
Not Included:
Section 18.4
4
Distribution Network Optimisation
Included:
Sections 19.1-19.2
5
Harmonic Analysis
Included:
Sections 20.1-20.4
6
Optimal Power Flow I (reactive power optimization)
Included:
Section 21.1 Active Power Controls disabled
7
Optimal Power Flow II (OPF I + economic dispatch)
Included:
Sections 21.1-21.2
8
Reliability Analysis
Included:
Sections 22.1-22.5
9
State Estimation (SE)
Included:
Section 23
10
Stability Analysis Functions
Included:
Section 24, DSL Crypt excluded Sections 25.1 (EMT excluded) Section 25.2.-25.3, 25.6 and 28.3
11
Electromagnetic Transients (EMT)
Included:
Section 24, DSL Crypt excluded Section 25.1 (RMS excluded) Section 25.4
12
Transient Motor Starting
Included:
Section 24, DSL Crypt excluded Section 25.3
13
Small Signal Stability (Eigenvalue Analysis)
Included:
Section 24, DSL Crypt excluded Section 26
14
Dynamic Parameter Identification
Included:
Section 24, DSL Crypt excluded Section 25.5 Stability Analysis Functions required
15
DSL Crypting Option
Included:
DSL Crypt (Section 24)
16
PSS/E Export (*.raw, *.seq, *.dyn)
Reference:
Section 7.1
17
CIM Import and Export
Reference:
Section 7.1
18
OPC Interface (Ole for Process Control)
Included:
Section 27.2
19
Shared Memory Communication
Included:
Section 27.3
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30.2 PowerFactory Prices The integrated PowerFactory v14 software is offered as Base Package with optional functional extensions allowing the user to configure the PowerFactory installation according to his specific needs. The Base Package itself is covering a comprehensive collection of core functions for integrated analysis of transmission, distribution, and industrial systems, most modern generation technologies (wind power, photovoltaic, microturbines, etc.) and Smart Grids.
Base Package
100 nodes
250 nodes
unlimited
max.
max.
no. of nodes
Workstation Edition
€ 3.900,-
€ 6.100,-
€ 9.800,-
Server Edition
€ 4.700,-
€7.300,-
€ 11.800,-
Edition
Indicated prices do not include any tax and shipping.
Prices of functional extensions can be requested from DIgSILENT and respective International Representatives.
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31 T h e D I g S I L E N T Co m p a n y
31 The DIgSILENT Company DIgSILENT GmbH is a consulting and software company providing specialized services in the field of electrical power systems for transmission, distribution, generation and industrial plants. DIgSILENT develops the leading integrated power system analysis software PowerFactory covering the full range from standard to highly sophisticated and advanced applications including real-time simulation and performance monitoring systems for system testing and supervision. DIgSILENT GmbH is staffed with experts of various disciplines relevant for performing research activities, consulting services, user training and educational programs and software developments. Special expertise is available in many actual fields of electrical engineering for the liberalized power markets and latest developments in power generation technologies such as wind power and dispersed generation. DIgSILENT GmbH founded in 1985 is a fully independent, privately owned company located in Gomaringen, Germany where the new offices are in operation since early 2002. DIgSILENT continued expansion by establishing offices in Australia, South Africa, Italy, Spain and Chile allowing to better serve the world-wide increase in its software products and services. DIgSILENT has established a strong partner network in many countries such as Mexico, Malaysia, UK, Switzerland, Colombia, Brazil, Peru, Argentina, Iran, Saudi Arabia, Oman, India, China, Norway, Russia, Finland and Venezuela. DIgSILENT has software installations and conducted services in more than 110 countries.
DIgSILENT GmbH Heinrich-Hertz-Straße 9 72810 Gomaringen / Germany Phone: +49-7072-9168-0 Fax: +49-7072-9168-88 E-mail:
[email protected]
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