60017594-Chapter-19-ETAP-User-Guide-7-5-2

Chapter 19

Load Flow The ETAP Load Flow Analysis Module calculates the bus voltages, branch power factors, currents, and power flows throughout the electrical system. ETAP allows for swing, voltage regulated, and unregulated power sources with multiple power grids and generator connections. It is capable of performing analysis on both radial and loop systems. ETAP allows you to select from several different methods in order to achieve the best calculation efficiency. This chapter defines definitions and explains the usage of different tools you will need to run load flow studies. Theoretical background for different load flow calculation methods is also provided. The Load Flow toolbar section explains how you can launch a load flow calculation, open and view an output report, or select display options. The Load Flow Study Case Editor section explains how you can create a new study case, what parameters are required to specify a study case, and how to set them. The Display Options section explains what options are available for displaying some key system parameters and the output results on the one-line diagram, and how to set them. The Load Flow Calculation Methods section shows formulations of different load flow calculation methods. Comparisons on their rate of convergence, improving convergence based on different system parameters and configurations, and some tips on selecting an appropriate calculation method are also found in this section. The Required Data for Calculations section describes what data is necessary to perform load flow calculations and where to enter them. The Load Flow Study Output Report section illustrates and explains output reports and their format. Finally, the Load Flow Result Analyzer allows you to view the results of various studies in one screen so you can analyze and compare the different results.

Operation Technology, Inc.

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ETAP 7.5.2 7.5.2 User Guide

Load Flow Analysis

Toolbar

19.1 Load Flow Toolbar The Load Flow toolbar will appear on the screen when you are in the Load Flow Study Mode.

Run Load Flow Studies Run Control Auto Simulator Load Flow Display Options Alert View Load Flow Report Manager Halt Current Calculation Get Online Data Get Archived Data Load Flow Comparator Load Flow Result Analyzer Load Analyzer

Run Load Flow Studies Select a Study Case from the Study Case Editor. Then click on the Run Load Flow Study icon to perform a load flow study. A dialog box will appear to specify the output report name if the output file name is set to Prompt. The study results will then appear on the one-line diagram and in the Output Report.

Run Control Auto Simulator The Control Auto Simulator capability allows the ETAP program to generate operating values and emergency conditions of a power system and feeds the information to actual control systems of generators. You can specify emergency conditions to be simulated, including generator governor and exciter control modes and associated causes as well as circuit breaker status changes and associated causes from the Emergency page of the Load Flow Study Case. This feature can be used to test and tune the setting and reaction time of the physical control systems of your generators. Note: ETAP Real-Time is needed in order to enable this feature.


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Load Flow Analysis

Toolbar

19.1 Load Flow Toolbar The Load Flow toolbar will appear on the screen when you are in the Load Flow Study Mode.

Run Load Flow Studies Run Control Auto Simulator Load Flow Display Options Alert View Load Flow Report Manager Halt Current Calculation Get Online Data Get Archived Data Load Flow Comparator Load Flow Result Analyzer Load Analyzer

Run Load Flow Studies Select a Study Case from the Study Case Editor. Then click on the Run Load Flow Study icon to perform a load flow study. A dialog box will appear to specify the output report name if the output file name is set to Prompt. The study results will then appear on the one-line diagram and in the Output Report.

Run Control Auto Simulator The Control Auto Simulator capability allows the ETAP program to generate operating values and emergency conditions of a power system and feeds the information to actual control systems of generators. You can specify emergency conditions to be simulated, including generator governor and exciter control modes and associated causes as well as circuit breaker status changes and associated causes from the Emergency page of the Load Flow Study Case. This feature can be used to test and tune the setting and reaction time of the physical control systems of your generators. Note: ETAP Real-Time is needed in order to enable this feature.


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Load Flow Analysis

Toolbar

Load Flow Display Options The results from load flow studies are displayed on the one-line diagram. To edit how these results look, click on the Load Flow Display Options icon. For more information see Load Flow Display Options.

Alert View After performing a load flow study, you can click on this button to open the Alert View, which lists all equipment with critical and marginal violations based on the settings in the study case.

Load Flow Report Manager Load Flow Output Reports are provided in the form of a Crystal Report. The Report Manager provides four pages (Complete, Input, Result, and Summary) for viewing the different parts of the output report for Crystal Reports. Available formats for Crystal Reports are displayed in each page of the Report Manager for load flow studies. You can view the report in the Crystal Reports viewer, or save the report in PDF, MS Word, Rich Text Format, or Excel format. If you wish this selection to be the default for reports, click the Set As Default checkbox.

Choosing any format in the Report Manager activates the Crystal Reports. You can open the whole load flow output report or only a part of it, depending on the format selection. The format names and corresponding output report sections are given below:

• • • • •

Adjustments Alert-Complete Alert-Critical Alert-Marginal Branch Loading


Indicates tolerance and temperature correction adjustments Provides complete report of system alerts Provides summary of critical alerts only Provides summary of marginal alerts only Branch loading results

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Load Flow Analysis • Branch • Bus Loading • Bus • Cable • Complete • Cover • Equipment Cable • High Voltage DC Link • Impedance • Line Coupling • Load Flow Report • Losses • NO Protective Devices • Panel Report • Reactor • Summary • SVC • Transformer • UPS Report

Toolbar Branch input data Displays overloaded bus information Bus input data Cable input data Complete output report including all input and output Title page of the output report Equipment cable input data High Voltage DC Link input data Provides detailed information about impedance elements in the system Displays Transmission Line coupling impedance data Load Flow calculation results Branch loss results Displays Normally Open protective devices Load Flow calculation results for panel systems Reactor input data Summary of load flow calculation Static Var Compensator (SVC) input data Transformer input data Load Flow calculation results for UPS systems

You can also view output reports by clicking on the View Output Report button on the Study Case toolbar. A list of all output files in the selected project directory is provided for load flow calculations. To view any of the listed output reports, click on the output report name, and then click on the View Output Report button.

Halt Current Calculation The Stop Sign button is normally grayed-out. When a Load Flow calculation has been initiated, this button becomes enabled and shows a red stop sign. Clicking on this button will terminate the calculation.

Get Online Data When ETAP Real-Time is set up and the Sys Monitor presentation is online, you can bring real-time data into your offline presentation and run a Load Flow by pressing on this button. You will notice that the Operating Loads, Bus Voltages, and Study Case Editor will be updated with the online data.

Get Archived Data When ETAPS Playback is set up and any presentation is on Playback Mode, you can bring this data into your presentation and run a Load Flow by pressing on this button. You will notice that the Operating Loads, Bus Voltages, and Study Case Editor will be updated with the playback data.

Load Flow Comparator


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ETAP 7.5.2 User Guide

Load Flow Analysis

Toolbar

When ETAP Real-Time is set up and after you run a Load Flow study with online data, you can press this button to bring up the Load Flow Comparator view. It lists comparison of all system operating values between ETAP Real-Time output and Load Flow calculations.

Load Flow Result Analyzer The Load Flow Result Analyzer allows you to view the results of various studies in one screen so you can analyze and compare the different results.

Load Analyzer The Load Analyzer tool and its associated reports are designed for load sched ule reporting of ETAP models. This module allows the user to report loads of multilevel-connected elements in a system directly (called Connected Loads), or b y applying different multiplying factors (called Operating Loads).


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Load Flow Analysis

Study Case Editor

19.2 Study Case Editor The Load Flow Study Case Editor contains solution control variables, loading conditions, and a variety of options for output reports. ETAP allows you to create and save an unlimited number of study cases. Load flow calculations are conducted and reported in accordance with the settings of the study case selected in the toolbar. You can easily switch between study cases without having to reset the study case options each time. This feature is designed to organize your study efforts and save you time. As a part of the multi-dimensional database concept of ETAP, study cases can be used for any combination of the three major system toolbar components, i.e. for any configuration status, one-line diagram presentation, and Base/Revision data. When you are in Load Flow Analysis Mode, you can access the Load Flow Study Case Editor by clicking on the Study Case button from the Load Flow Study Case toolbar. You can also access this editor from the Project View by clicking on the Load Flow Study Case folder.

There are two ways you can create a new study case. You can click on the New Study Case button in the Study Case toolbar, as shown above. It will open the Duplicate Study Case dialog box for you to specify names of an existing Study Case and the new study case you want to create.

You can also create a new Study Case from the Project View, by right-clicking on the Load Flow Study Case folder and selecting Create New. ETAP will then create a new study case, which is a copy of the default Study Case, and adds it to the Load Flow Study Case folder.


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Load Flow Analysis


Study Case Editor

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Load Flow Analysis

Study Case Editor

19.2.1 Info Page

Study Case ID Study Case ID is shown in this entry field. You can rename a Study Case by deleting the old ID and entering the new ID. Study Case ID can be up to 12 alphanumeric characters. Use the Navigator button at the bottom of the editor to go from one study case to the next existing Study Case.

Method In this group you can select a load flow solution method. Three methods are available: Newton-Raphson, Fast-decoupled, and Accelerated Gauss-Seidel. For the Newton-Raphson, a few Gauss-Seidel iterations are made first to establish a set of sound initial values for the bus voltages (since convergence of the Newton-Raphson Method is highly dependent on the initial bus voltages).


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Study Case Editor

Max. Iteration Enter the maximum number for iterations in this field. If the solution has not converged before the specified number of iterations, the program will stop and inform you. The recommended and default values are 2000 for the Gauss-Seidel Method, and five for the Newton-Raphson and Fast-Decoupled Methods.

Precision Enter the value for the solution precision in this field, which is used to check for convergence. This value determines how precise you want the final solution to be. For the Gauss-Seidel Method, precision is applied to check the difference between the bus voltages after each iteration. For the Newton-Raphson and Fast-Decoupled Methods, the precision is compared with the difference in power for each bus (MW and Mvar) between iterations. If the difference between the iterations is less than or equal to the value entered for precision, the desired accuracy is achieved. If the solution converges but the mismatch values are high, reduce the value of the precision to make your results more precise and run the program again (you may need to increase the number of iterations). Note: A smaller precision value results in lower mismatch (higher accuracy), as well as a longer run time. The default (and recommended) values are 0.000001 pu volts for the Gauss-Seidel Method, and .0001 pu power for the Newton-Raphson and Fast-Decoupled Methods.

Accel. Factor This field is present if the Accelerated Gauss-Seidel Method is used. Enter the convergence acceleration factor to be used between iterations. Typical values are between 1.2 and 1.7; the default is 1.45.

Apply XFMR Phase-Shift Check this box to consider transformer phase-shift in load flow calculations. The phase-shift of a transformer can be found in the Transformer Editor.

Calc. Panel/UPS Systems Check this box to include panel and/or UPS system load flow calculations as part of the whole system load flow calculation. A panel/UPS system is defined as a radial sub-system that is powered through a top panel, UPS, or a phase adaptor connected to a 3-phase bus. A power system may contain several panel/UPS systems. Each panel/UPS system has a top element that is a 3-phase panel, 3-phase UPS, or a phase adapter. If this box is checked, bus voltages and branch flows in panel/UPS systems will be calculated in a load flow run and calculation results will be reported in the one-line diagram and the crystal report. If this box is not checked, the load for each panel/UPS system will be summed up to its top element for the loading specified in the study case. This load summation is based on the load rated voltage and does not consider any branch losses. The top element will be treated as a single load in the system. The panel/UPS system must be a radial system. ETAP checks loop configurations in panel/UPS systems when performing load flow calculations. Should a loop configuration be detected, the load flow calculation will be terminated and a message will be posted.

Update In this group, you can decide to update initial conditions of the buses and/or set the transformer taps to the calculated value of LTCs. The selected options will be updated after the subsequent load flow run.


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Load Flow Analysis

Study Case Editor

Initial Bus Voltage Select this option to update the values of the bus voltage magnitudes with the result of the load flow run. Bus voltage update will result in a faster convergence of the subsequent load flow solutions since the initial bus voltages will be closer to the final values.

Inverter Operating Load In an AC load flow study, an inverter is represented as a constant voltage source. When this option is checked, the load provided by the inverter will be updated to the inverter element, which can be used later as DC load of the inverter in a DC Load Flow Study.

Operating Load & V The option is available if your ETAP key has the online feature. When this box is checked, the calculation results will be updated to sources, loads, and buses, so that they can be utilized as input for later studies. These values are also displayed in element editors. If your ETAP key does not have the online feature, you can see the operating P, Q, and V in only element editors, and they cannot be used in a later study.

Transformer LTCs Select this option to update the transformer taps to reflect the result of load tap changer (LTC) settings, i.e., transformer taps will be set to values determined from the load flow solution for LTCs. This feature is useful when you want to consider the impedance of the LTC taps for short-circuit calculations. Selecting this option will also display the LTC settings on the OLV.

Cable Load Amp Select this option to transfer cable load current data from the previously run load flow study. The data is transferred to the Operating Load Current in the Cable Editor for each cable associated with the load flow study.

Report Bus Voltage Calculated bus voltages seen in the output report can be printed in kV or in percent of the bus nominal voltages. Select your preference by clicking on in Percent or in kV. For graphical display of bus voltages see Load Flow Display Options.

Equipment Cable Losses and Vd Select this option to print an equipment cable losses and voltage drop report. Once this option is selected, you will have the option to Exclude Load Diversity Factor. Checking this option will exclude the load diversity factor in the calculations of equipment cable losses and voltage drop in the report only. For more information on load diversity factors, see the Loading page of the Load Flow Study Case Editor.

Initial Voltage Condition Initial conditions for all bus voltages and angles can be specified in this section for load flow calculation purposes.

Bus Initial Voltages Select this option to use bus voltages and angles as entered in the Info page of the Bus Editors. Using this option, you can simulate load flow studies with different initial conditions for bus voltage.


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Study Case Editor

User-Defined Fixed Value This option allows you to simulate load flow studies using a fixed bus voltage and angle for all buses. When you select the fixed initial condition option, you must enter the initial voltage value as the percent of the bus nominal voltage. The default values are 100% for bus voltage magnitude and zero degree for bus voltage angle.

Determination of Initial Bus Voltage Angle When transformer phase-shift is considered in the load flow calculation, the initial bus voltage angle should be taken into account. Otherwise, very poor initial bus voltage angle may be used and which may affect load flow convergence. To resolve this issue, the ETAP Load Flow Module calculates the bus voltage angle-based on transformer phase-shift and compares the calculated value against the initial bus voltage angle from user selected option. If the difference between the two values is larger than the specified MaxIniAngDiff, ETAP uses the calculated the values as the initial bus voltage angle, where MaxIniAngDiff is an ETAP.INI file entry defaulted at 10. According to the selection for the initial bus voltage and the Apply XFMR Phase-Shift field, there are four different situations:

•

When the Use Fixed Values is checked and the Apply XFMR Phase-Shift is also checked, the calculated initial bus voltage angles are used in the load flow calculation.

•

When the Use Bus Voltages is checked and the Apply XFMR Phase-Shift is also checked, the initial bus voltage angle from the Bus Editor is compared against the calculated bus voltage angle. If the difference is less than MaxIniAngDiff, the initial bus voltage angle from the Bus Editor is used; otherwise the calculated value is used in the load flow calculation.

•

When the Use Fixed Values is checked and the Apply XFMR Phase-Shift is not checked, the initial voltage angle entered in the Load Flow Study Case is used in the load flow calculation. In this case, all the buses have the same initial voltage angle.

•

When the Use Bus Voltages is checked and the Apply XFMR Phase-Shift is not checked, the initial bus voltage angles from the Bus Editor are used in the load flow calculation.

When the operating load is specified as the system load, the operating voltage angles are used as the initial value. In this case, if the Apply XFMR Phase-Shift is checked, the operating voltage angle is compared against the calculated bus voltage angle. If the difference is less than MaxIniAngDiff, the operating voltage angle is used; otherwise the calculated value is used in the load flow calculation.

Study Remarks You can enter up to 120 alphanumeric characters in this remarks field. Information entered in this location will be printed on the second line of every output page header line. These remarks can provide specific information for each study cases. The first line of the header information is global for all study cases and is entered in the Project Information Editor.


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Study Case Editor

19.2.2 Loading Page

Loading Category Select one of the ten Loading Categories for the current Load Flow Study. With the selection of any category, ETAP uses the percent loading of individual motors and other loads as specified for the selected category. Note: You can assign loading to each one of the ten categories from the Nameplate page of the Induction Machine Editor and Synchronous Motor Editor and the Loading or Rating page of other load component editors.

Operating P, Q This option is available if your ETAP key has the online feature. When this box is checked, the operating loads updated from online data or a previous Load Flow Study will be utilized in the Load Flow Study.

Generation Category


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Load Flow Analysis

Study Case Editor

Select one of the ten Generation Categories for the current Load Flow Study. With the selection of any category, ETAP uses the generator controls for the selected category, as specified in the Rating page of the Generator Editor. The generator controls will be different depending on the mode that the generator is operating under. The mode of generation is selected on the Info page of the Generator Editor. The table below shows the generation controls with respect to the mode of generation. Mode Swing Voltage Control MVAR Control PF Control

Generation Category Control %V and Angle %V and MW MW and MVAR MW and PF

Operating P, Q, V This option is available if your ETAP key has the online feature. When this box is checked, the generator operating values updated from online data or a previous load flow study will be utilized in the Load Flow Study.

Load Diversity Factor This section allows you to specify load diversity factors to be applied on the loading category load. When the Operating Load is selected, a diversity factor is not considered.

None Select ‘None’ to use the percent loading of each load as entered for the selected Loading Category.

Bus Minimum When the minimum bus loading option is selected, all motors and other loads directly connected to each bus will be multiplied by the bus minimum diversity factor. Using this option, you can simulate load flow studies with each bus having a different minimum diversity factor. The minimum bus loading study option may be used to see the effect of transformer taps and capacitors (if any) on the system voltages under a minimum (light) loading condition.

Bus Maximum When the Maximum Loading option is selected, all motors and other loads directly connected to each bus will be multiplied by the bus maximum diversity factor. Using this option, you can simulate load flow studies with each bus having a different maximum diversity factor. This study option is helpful when the future loading of the electrical system has to be considered and each bus may be loaded at a different maximum value.

Global Diversity Factor Enter the diversity factors for all constant kVA, constant Z, generic, and constant I loads. When you select this option, ETAP will globally multiply all motors, static loads, constant current loads, and generic loads of the selected Loading Category with the entered values for the respective load diversity factors.

Constant kVA Constant kVA loads include induction motors, synchronous motors, conventional and unbalanced lumped loads with % motor load, UPS’s, and chargers.


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Load Flow Analysis

Study Case Editor

Constant Z Constant impedance loads include static loads, capacitors, harmonic filters, MOV’s, and conventional and unbalanced lumped loads with % static load.

Constant I Constant current loads include unbalanced lumped loads with % constant current load.

Generic Generic loads include lumped loads modeled using either the exponential, polynomial, or comprehensive model. Please refer to the Section 15.4 (Calculations Methods) for the load-modeling concepts used in ETAP. Note: A motor load-multiplying factor of 125% implies that the motor loads of all buses are increased by 25 percent above their nominal values. This value can be smaller or greater than 100 percent.

Charger Loading You have the option to use the Loading Category or the Operating Load for chargers. The operating load for a charger can only be updated from a DC Load Flow Study.


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Study Case Editor

19.2.3 Adjustments Page This page allows you to specify tolerance adjustments to length, equipment resistance, and impedance. Each tolerance adjustment can be applied based on the individual equipment percent tolerance setting or based on a globally specified percent value.

Impedance Tolerance This group allows you to consider tolerance adjustments to impedance values for transformer, reactor, and overload heater.

Transformer Impedance Adjustment This adjustment is applied to transformer impedance. The net effect of the transformer impedance adjustment in load flow calculations is to increase the impedance by the specified percent tolerance value. For example, if the transformer impedance is 12% and the tolerance is 10%, the adjusted impedance used in the load flow calculation will be 13.2%, resulting in higher losses. The Impedance Adjustment can be applied to individual transformers by using the tolerance percent value specified in the Transformer Editor Rating page. A global Transformer Impedance Adjustment can be


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Study Case Editor

specified as well by selecting and specifying a global tolerance other than 0% in the corresponding field of Load Flow Study Case Editor Adjustment page. The global Impedance Adjustment overrides any individual transformer tolerance value.

Reactor Impedance Adjustment This adjustment is applied to the reactor impedance. The Load Flow Module increases the reactor impedance by the specified percent tolerance resulting in larger impedance and consequently a larger voltage drop. For example, if the impedance of the reactor is 0.1 Ohm and its tolerance is 5%, then the adjusted reactor impedance used in the load flow calculation is 0.105 Ohm. The Impedance Adjustment can be applied to individual reactors by using the tolerance percent value specified in the Reactor Editor Rating page. A global Reactor Impedance Adjustment can be specified as well by selecting and specifying a global tolerance other than 0% in the corresponding field of the Load Flow Study Case Editor Adjustment page. The global Impedance Adjustment overrides any individual reactor tolerance value.

Overload Heater Resistance This adjustment is applied to the overload heater (OH) resistance. The Load Flow Module increases the OH resistance by the specified percent tolerance resulting in a larger resistance and consequently a larger voltage drop. For example, if the resistance of the OH is 0.1 Ohm and its tolerance is 5%, then the adjusted OH resistance used in the load flow calculation is 0.105 Ohm. The Resistance Adjustment can be applied to individual overload heaters by using the tolerance percent value specified in the Overload Heaters Editor Rating page. A global Overload Heater Resistance Adjustment can be specified as well by selecting and specifying a global tolerance other than 0% in the corresponding field of Short Circuit Study Case Editor Adjustment page. The global Resistance Adjustment overrides any individual overload heater tolerance value.

Length Tolerance This section allows you to consider tolerance adjustments to cable and transmission line lengths.

Cable Length Adjustment This adjustment is applied to the cable length. The Load Flow Module increases the cable length by the specified percent tolerance resulting in larger impedance and consequently a larger voltage drop. For example, if the length of the cable is 200 ft. and the tolerance is 5%, then the adjusted cable length used in the load flow calculation is 210 ft. The Length Adjustment can be applied to individual cables by using the tolerance percent value specified in the Cable Editor Info page. A global Cable Length Adjustment can be specified as well by selecting and specifying a global tolerance other than 0% in the corresponding field of the Load Flow Study Case Editor Adjustment page. The global Length Adjustment overrides any individual cable tolerance value.

Transmission Line Length Adjustment This adjustment is applied to the transmission line length. The Load Flow Module increases the transmission line length by the specified percent tolerance resulting in larger impedance and consequently a larger voltage drop. For example, if the length of the transmission line is 2 miles and the tolerance is 2.5%, then the adjusted transmission line length used in the load flow calculation is 2.05 miles. The Length Adjustment can be applied to individual lines by using the tolerance percent value specified in the Transmission Line Editor Info page. A global Transmission Line Length Adjustment can be


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Load Flow Analysis

Study Case Editor

specified as well by selecting and specifying a global tolerance other than 0% in the corresponding field of the Load Flow Study Case Editor Adjustment page. The global Length Adjustment overrides any individual transmission line tolerance value.

Resistance Temperature Correction This group allows you to consider resistance correction based on the maximum operating temperature for cable and transmission line conductors. Each temperature resistance correction can be applied based on the individual cable/line maximum temperature setting or based on a globally specified value.

Temperature Correction for Cable Resistance This adjustment is applied to the cable conductor resistance. The Load Flow Module adjusts the conductor resistance based on the maximum operating temperature. If the maximum operating temperature is greater than the rated base temperature of the conductor, then its resistance is increased. The temperature correction can be applied to individual cables by using the maximum operating temperature value specified in the Cable Editor Impedance page. A global temperature correction can be specified as well by selecting and specifying a global maximum temperature value in the corresponding field of the Load Flow Study Case Editor Adjustment page. The global temperature correction value overrides any individual Cable Impedance page maximum temperature. Please refer to the Cable Editor Impedance page section in Chapter 12 (AC-Editors).

Temperature Correction for Transmission Line Resistance This adjustment is applied to the transmission line conductor resistance. The Load Flow Module adjusts the conductor resistance based on the maximum operating temperature. If the maximum operating temperature is greater than the rated base temperature of the conductor, then the resistance is increased. The temperature correction can be applied to individual lines by using the maximum operating temperature value specified in the Transmission Line Editor Impedance page. A global temperature correction can be specified as well by selecting and specifying a global maximum temperature value in the corresponding field of the Load Flow Study Case Editor Adjustment page. The global temperature correction value overrides any individual Transmission Line Impedance page maximum temperature. Please refer to the Transmission Line Editor Impedance page section in Chapter 12 (AC-Editors).


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Load Flow Analysis

Study Case Editor

19.2.4 Alert Page The Alert page in the Load Flow Study Case Editor is used to specify the setup of all the Simulation Alerts that are provided to notify you of an abnormal loading condition based on predetermined, “allowable”, percent values and system topology. The functional capability of the Simulation Alert System is to generate alerts when there is an overload in protective devices, buses, transformers, cables, lines, panels, DC links, reactors, generators, and power grid. The alerts are reported by the generation of different types of alerts, either graphically in the one-line diagram display or in the Alert View window.

Critical and Marginal Alerts There are two types of simulation alerts generated after a Load Flow Study. The difference between Marginal and Critical Alerts is their use of different percent value conditions to determine if an alert should be generated. If a condition for a Critical alert is met, then an alert will be generated in the Alert View window and the overloaded element will turn red in the one-line diagram. The same is true for Marginal Alerts, except that the overloaded component will be displayed in magenta color. Also, the Marginal Alerts checkbox must be selected if you wish to display the Marginal Alerts. If a device alert qualifies it for both Critical and Marginal alerts, only Critical Alerts are displayed. It should be noted that in order for ETAP to generate alerts for an element type, both the element rating and the percent value


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Study Case Editor

entered in this page must be non-zero. The element ratings for alert checking are given in the following sections.

Loading This set of value fields allows you to enter the condition percent values of the monitored parameters used to determine if an alert should be reported based on loading conditions determined by a load flow calculation. The Load Flow Loading Alerts generate overload alerts.

Bus Alert The Load Flow Module will generate a Bus Loading Alert if the Critical or Marginal percent limit of rated continuous current in the bus is exceeded. The rated continuous current in the bus is specified in the Rating page of the Bus Editor.

Cable Alert The Load Flow Module will generate a Cable Alert if the Critical or Marginal percent limit of allowable ampacity in the cable is exceeded. The allowable ampacity of the cable is specified in the Ampacity page of the Cable Editor.

Line Alert The Load Flow Module will generate a Line Alert if the Critical or Marginal percent limit of derated ampacity in the transmission line is exceeded. The derated ampacity of the transmission line is calculated in the Ampacity page of the Transmission Line Editor.

Reactor Alert The Load Flow Module will generate a Reactor Alert if the Critical or Marginal percent limit of rated current in the reactor is exceeded. The rated current in the reactor is specified in the Rating page of the Reactor Editor.

Transformer Alert The Load Flow Module will generate a Transformer Alert if the Critical or Marginal percent limit of maximum MVA of the transformer is exceeded. The maximum MVA of the transformer is specified in the Rating page of the Transformer Editor. The simulation alerts work for both 2 and 3-winding transformers.

Panel Alert The Load Flow Module will generate a Panel Alert if the Critical or Marginal percent limit of rated current in the panel is exceeded. The rated current of the panel is specified in the Rating page of the Panel Editor.

Protective Device Alert The Load Flow Module will generate Protective Device Alerts when certain predetermined parameter value ratings are exceeded. The following table contains a list of the conditions used by the Alert Simulation program to determine when to report an alert. Load flow results are compared to the monitored parameters listed in the following table:


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Study Case Editor

Protective Devices

Monitored parameters in percent of

Condition reported

Low Voltage Circuit Breaker High Voltage Circuit Breaker Fuses Contactors SPDT/SPST switches

Continuous rated Current Continuous rated Current Rated Current Continuous rated Current Continuous rated Current

OverLoad OverLoad OverLoad OverLoad OverLoad

The Load Flow Module will generate Protective Device Alerts only if the monitored parameter rating is larger than zero.

Generator Alert The Load Flow Module will generate a Generator Alert if the Critical or Marginal percent limit of rated MW of the generator is exceeded. The rated MW of the generator is specified in the Rating page of the Generator Editor.

Bus Voltage Alerts Bus Voltage Simulation Alerts generate alerts if the voltage magnitude percent results from the load flow calculation exceed or are below the specified nominal kV rating percent values. Bus Voltage Alerts report over voltage and under voltage alerts.

Generator/Power Grid Excitation Alerts Simulation Alerts for generator and power grid excitation monitor the percent rated var limits. An alert for Over Excitation is reported if the Upper Excitation percent limit (Qmax) for the generator is exceeded according to a load flow calculation. An alert for Under Excitation is reported if the generator Mvar result from the load flow calculation is below the specified Lower Excitation percent limit (Qmin). You have the option to run the load flow calculation without monitoring Under Excitation conditions. An alert for Under Excitation will be reported if the UnderExcited (Qmin) checkbox is selected. The Under Excitation percent limit for the generator is 100% of Q min. ETAP also has two alerts for the generator built into the load flow calculation. ETAP will produce an Under-Power alert if the real power output of the generator, from the load flow calculation, is less than the value of P min. You can specify Pmin in the Capability page of the Generator Editor. P min must be nonzero in order for ETAP to generate the alert. Also, if the generator is modeled in Swing Mode, it will absorb real power in load flow if necessary; therefore, ETAP will produce a P out<0 alert for Swing Mode generators if the real power output from the load flow calculation is negative.

Marginal Limit If the Marginal Limit option is checked, the Alert View window will display the marginal alerts as well. If not selected, the Alert View window will display only the critical alerts.

Auto Display If the Auto Display option is checked, the Alert View window automatically opens after the load flow calculation completes. If not checked, the Alert View window can be opened by clicking the Alert View icon on the Load Flow toolbar.


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Calculation Methods

19.3 Display Options 19.3.1 Results Page The Load Flow Analysis Display Options consist of a Results page and three pages for Results, AC, ACDC, and Colors information annotations. The colors and displayed annotations selected for each study are specific to that study.

Show Units Select this option to show units for power flow and current displayed on the one-line diagram.

Check All Select this option to show all available result annotations. When this box is unchecked, the previous settings are restored.


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Calculation Methods

Voltage Voltage Select kV or percent for voltage display on the one-line diagram from the list.

Bus Mag. Select this option to display bus voltages on the one-line diagram. Bus voltages are displayed at 15 degrees.

Bus Angle Select this option to display bus angles in degrees on the one-line diagram. Bus angles are displayed at -15 degrees.

Load Term. Mag. Select this option to display load (motors and static loads) terminal voltages on the one-line diagram. Load terminal voltages are displayed at 15 degrees. Load terminal voltages can be displayed based on load rated kV or bus nominal kV, depending on the selection in Load Term. Base kV.

Load Term. Base kV This group allows you to select base kV for load terminal magnitude, when the voltage is selected to be displayed in percent. This group will be disabled if it is selected to display voltage in kV.

Load Rated kV Select this option to use load rated kV as the base for load terminal voltage display.

Bus Nom. kV Select this option to use bus nominal kV as the base for load terminal voltage display.

Voltage Drop Line/Cable Select this option to display line and cable voltage drops on the one-line diagram.

Load FDR Select this option to display the load feeder voltage drops.

Panel/UPS Systems Results Select this option to display results for panel systems in the one-line diagram, assuming that the Calc. Panel/UPS System option has been checked in the study case when the load flow calculation was carried out. If the Calc. Panel System option has not been checked in the load flow study case or the panel system display option is not checked, no results will be displayed in the one-line diagram.

Average Values Select this option to display average values for panel system results as shown in the following table.


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Calculation Methods

Panel System Load Flow Results Displayed in Average Values Phase Type Voltage Current Power 3-Phase Average Value Average Value Total Power 1-Phase, 3-Wire LL Value Average Value Total Power 1-Phase, 2-Wire Phase Value Phase Value Phase Value

Panel System Load Flow Results Displayed in Average Values All Phases Select this option to display individual phase values for panel system results. For 3-phase elements, voltage, current, and power for phases A, B, and C are displayed in sequence, and for one-phase threewire elements, voltage, current, and power for phases LL, L1, and L2 are displayed in sequence. Panel System Load Flow Results Displayed in All Phases Phase Type Voltage Current Power 3-Phase Phase A, B, & C Phase A, B, & C Phase A, B, & C 1-Phase, 3-Wire Phase LL, L1, & L2 Phase LL, L1, & L2 Phase LL, L1, & L2 1-Phase, 2-Wire Phase Value Phase Value Phase Value


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Load Flow Analysis

Calculation Methods

Panel System Load Flow Results Displayed in All Phases

Power Flows You can specify how the flows will be displayed in this area.

Units Select the unit ( kVA or MVA) to be used to display power flow on the one-line diagram.

kW + jkvar Select the kW + jkvar radio button to display power flow in kW+jkvar or MW+jMvar.

kVA Select the kVA radio button to display power flow in kVA or MVA.

Amp Select the Amp radio button to display current flow in amperes.

%PF When the Amp or kVA radio button is selected, you can check this box to show power factor of power flow along with the current.


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Calculation Methods

Flow Results Branch Select this option to display power flow through all branches on the one-line diagram. ETAP displays the power flow at one end of a branch, i.e., the end that has a positive kW value flowing into the branch. For 3-winding transformers, all three power flows are displayed.

Source Select this option to display power flow for generators and power grids on the one-line diagram.

Load Select this option to display power flow for motors, MOVs, capacitors, lumped loads, and static loads on the one-line diagram.

Composite Motor Select this option to display power flow into composite motors.

Composite Network Select the checkbox to display power flow into composite networks.

Branch Losses Select this option to display branch losses on the one-line diagram. Losses are displayed inside a bracket in [kW+jkvar] or [MW+jMvar].

Meters Ammeter Check this option to display primary current for the branch to which an ammeter is attached.

Voltmeter Check this option to display primary voltage for the bus to which a voltmeter is attached.

Multi-Meter Check this option to display the measurements of a multi-meter, including bus voltage, branch current, branch power flow, power factor, and frequency.


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19.3.2 AC Page This page includes options for displaying information annotations for AC elements.

ID Select the checkboxes under this heading to display the ID of the selected AC elements on the one-line diagram.

Rating Select the checkboxes under this heading to display the ratings of the selected AC elements on the oneline diagram.


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Load Flow Analysis

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Device Type Generator Power Grid (Utility) Motor Load Panel Transformer Branch, Impedance Branch, Reactor Cable/Line Bus Node CB Fuse Relay PT & CT

Rating

kW/MW MVAsc HP/kW kVA/MVA Connection Type (# Phases - # Wires) kVA/MVA Base MVA Continuous Amps Number of Cables - Number of Conductor/Cable - Size kA Bracing Bus Bracing (kA) Rated Interrupting (kA) Interrupting (ka) Display Tag, entered in Info Page of Relay Editor Transformer Rated Turn Ratio

kV Select the checkboxes under this heading to display the rated or nominal voltages of the selected elements on the one-line diagram. For cables/lines, click the checkboxes to display the cable/line and the size, length and type on the oneline diagram.

A Select the checkboxes under this heading to display the ampere ratings (continuous or full-load ampere) of the selected elements on the one-line diagram. For cables/lines, click the checkboxes to display the cable/line and the size, length and type on the oneline diagram.

Z Select the checkboxes under this heading to display the rated impedance of the selected AC elements on the one-line diagram. Device Type Generator Power Grid (Utility) Motor Transformer Branch, Impedance Branch, Reactor Cable/Line

Impedance

Subtransient Reactance Xd” Positive Sequence Impedance in % of 100 MVA (R + j X) % LRC Positive Sequence Impedance (R + j X per unit length) Impedance in Ohms or % Impedance in Ohms Positive Sequence Impedance (R + j X in Ohms or per unit length)

D-Y Select the checkboxes under this heading to display the connection types of the selected elements on the one-line diagram.


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Calculation Methods

For transformers, the operating tap setting for primary, secondary, and tertiary windings are also displayed. The operating tap setting consists of the fixed taps plus the tap position of the LTC.

Composite Mtr Click on this checkbox to display the AC composite motor IDs on the one-line diagram, then select the color in which the IDs will be displayed.

Use Default Options Click on this checkbox to use ETAP’s default display options. The checkboxes on this page will be grayed out.

Show Eq. Cable Click on this checkbox to display equivalent cables.


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Calculation Methods

19.3.3 AC-DC Page This page includes options for displaying information annotations for AC-DC elements and composite networks.

ID Select the checkboxes under this heading to display the IDs of the selected AC-DC elements on the oneline diagram.

Rating Select the checkboxes under this heading to display the ratings of the selected AC-DC elements on the one-line diagram.


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Load Flow Analysis

Device Type Charger Inverter UPS VFD

Calculation Methods

Rating AC kVA & DC kW (or MVA/MW) DC kW & AC kVA (or MW/MVA) KVA HP/kW

kV Click on the checkboxes under this heading to display the rated or nominal voltages of the selected elements on the one-line diagram.

A Click on the checkboxes under this heading to display the ampere ratings of the selected elements on the one-line diagram. Device Type Charger Inverter UPS

Amp AC FLA & DC FLA DC FLA & AC FLA Input, output, & DC FLA

Composite Network Click on this checkbox to display the composite network IDs on the one-line diagram, then select the color in which the IDs will be displayed.

Use Default Options Click on this checkbox to use ETAP’s default display options.


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Load Flow Analysis

Calculation Methods

19.3.4 Colors Page This page includes options for assigning colors to annotations for elements on the one-line diagram.

Color Theme A previously defined color theme can be selected from the list. The selected color theme will be used whenever the Theme option button is selected. Annotations This area allows you to assign colors to AC and DC elements, composite elements, and displayed results. Theme This option allows the global color theme selected in the color Theme list for element annotations to be applied globally throughout all diagrams. When the option is selected, the name assigned to the applied color theme is also displayed in a box at the right of the button.


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User-Defined Select this option to specify a color for element annotations. When this option is chosen, the DC element annotation color selection list will appear.

Theme Button Click this button to make the Theme Editor appear.

Theme Editor The Theme Editor allows you to select existing color themes or define a new color theme. Note that color themes are applied globally within a project file. Changes made on a color theme displayed on this page may also affect other modes and presentations if the global color themes option has been previously selected.


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Calculation Methods

19.4 Calcula Calc ulatio tion n Me M ethods hods ETAP provides three load flow calculation methods: Newton-Raphson, Fast-Decoupled, and Accelerated Gauss-Seidel. They possess different convergent characteristics, and sometimes one is more favorable in terms of achieving the best performance. You can select any one of them depending on your system configuration, generation, loading condition, and the initial bus voltages.

Newton-Raphson Method The Newton-Raphson Method formulates and solves iteratively the following load flow equation:

⎡ ΔP ⎤ ⎡ J1 ⎢ ΔQ ⎥ ⎢ J ⎣ ⎦⎣ 3

⎡ Δδ ⎤ = J 4 ⎥⎦ ⎢⎣ ΔV ⎥⎦ J2 ⎤

where ΔP and ΔQ are bus real power and reactive power mismatch vectors between specified value and calculated value, respectively; ΔV and Δδ represents bus voltage magnitude and angle vectors in an incremental form; and J 1 through J 4 are called Jacobian matrices. The Newton-Raphson Method possesses a unique quadratic convergence characteristic. It usually has a very fast convergence speed compared to other load flow calculation methods. It also has the advantage that the convergence criteria are specified to ensure convergence for bus real power and reactive power mismatches. This criterion gives you direct control of the accuracy you want to specify for the load flow solution. The convergence criteria for the Newton-Raphson Method are typically set to 0.001 MW and Mvar. The Newton-Raphson Method is highly dependent on the bus voltage initial values. A careful selection of bus voltage initial values is strongly recommended. Before running load flow using the Newton-Raphson Method, ETAP makes a few Gauss-Seidel iterations to establish a set of sound initial values for the bus voltages. The Newton-Raphson Method is recommended for use with any system as a first choice.

Fast-Decoupled Method The Fast-Decoupled Method is derived from the Newton-Raphson Method. It takes the fact that a small change in the magnitude of bus voltage does not vary the real power at the bus appreciably, and likewise, for a small change in the phase angle of the bus voltage, the reactive power does not change appreciably. Thus the load flow equation from the Newton-Raphson Method can be simplified into two separate decoupled sets of load flow equations, which can be solved iteratively:

[ ΔP ] = [ J1 ][][ Δδ ] [ ΔQ] = [ J 4 ][][ ΔV ] The Fast-Decoupled method reduces computer memory storage by approximately half, compared to the Newton-Raphson method. It also solves the load flow equations using significantly less computer time than that required by the Newton-Raphson method, method, since the Jacobian matrices are constant. As with the Newton-Raphson Method, convergence criteria of the Fast-Decoupled Method is based on real power and reactive power mismatches, which are typically set to 0.001 in the order of MW and Mvar.


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Although for a fixed number of iterations it is not as accurate as the Newton-Raphson Method, the savings in computer time and the more favorable convergence criteria makes for a very good overall performance. In general, the Fast-Decoupled Method can be used as an alternative to the Newton-Raphson Method, and it should definitely be given a try if the Newton-Raphson Method has failed when dealing with long radial systems or systems that have long transmission lines or cables.

Accelerated Gauss-Seidel Method From the system nodal voltage equation

[I ] = [YBUS ][V ] the Accelerated Gauss-Seidel Method derives the following load flow equation and solves it iteratively:

[P +

[ ][

][ ]

* jQ] = V T YBUS V*

where P and Q are specified bus real and reactive power vectors, V is the bus voltage vector, and Y BUS is the system admittance matrix. Y *BUS and V* are the conjugates of Y BUS and V respectively. V T is the transpose of V. The Accelerated Gauss-Seidel Method has relatively lower requirements of the bus initial voltage values compared to the Newton-Raphson Method and the Fast-Decoupled Method. Instead of using bus real power and reactive power mismatch as convergence criteria, the Accelerated Gauss-Seidel Method checks bus voltage magnitude tolerance between two consecutive iterations to control the solution precision. The typical value value for bus voltage magnitude magnitude precision is set to 0.000001 0.000001 pu. The Accelerated Gauss-Seidel Method has a slower convergence speed. When you apply appropriate acceleration factors, a significant increase in the rate of convergence can be obtained. The range for the acceleration factor is between 1.2 and 1.7, and is typically set to 1.45.

Load Flow Convergence As in any iterative solution method, the convergence of the load flow solution is affected by a number of factors specific to power systems.

Negative Impedance Negative resistance and reactance should be avoided. For example, the traditional method of modeling 3winding transformers by a Y equivalent model using one impedance and two 2-winding transformers, could sometimes result in a negative impedance value for one of the impedance branches. In this case, the negative impedance should be combined with other series circuit elements so that the result is a positive impedance value. Load flow calculations may not converge if a large value of negative impedance is used. ETAP can now model 3-winding transformers directly with no need for you to do any conversions.

Zero or Very Small Impedance A zero or very small impedance value of any branch is not allowed, since this will result in infinity or a huge number in the system admittance matrix. You should represent this type of impedance by a tie circuit breaker to solve the problem.


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Calculation Methods

Widely Different Branch Impedance Values Widely different branch impedance values on the same per unit base may result in a slow convergence. To avoid this situation, various techniques, such as combining series branches with low impedance values, ignoring short length transmission lines and/or cables, or modeling a small impedance branch with tie circuit breakers, can be employed.

Long Radial System Configurations Long radial system configurations usually take a longer time to converge than loop configurations. In general, the Fast-Decoupled Method works faster than the Newton-Raphson or the Accelerated GaussSeidel Method for radial system.

Bad Bus Voltage Initial Values Solution convergence speed and computing time are functions of the initial voltages for load-type buses. The closer the initial voltages are to their final profile, the faster the solution converges. The solution may not converge if the initial voltages are too far from the final profile, thus it is recommended that the Update Bus Voltage option be used to obtain a set of sound initial bus voltages.

Modeling of Loads Constant Power Load Constant power loads include induction motors, synchronous motors, conventional and unbalanced lumped loads with % motor load, UPS’s, and chargers. The power output remains constant for all changes in input voltage. Below are the respective I-V and P-V curves for a constant power load:

Constant Impedance Load Constant impedance loads include static loads, capacitors, harmonic filters, MOV’s, and conventional and unbalanced lumped loads with % static load. The input power increases proportionally to the square of the input voltage. Below are the respective I-V and P-V curves for a constant impedance load:

Constant Current Loads Constant current loads include unbalanced lumped loads with % constant current load. The current remains constant for all changes in voltage. Below are the respective I-V and P-V curves for a constant current load:


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Calculation Methods

Generic Load Generic loads include lumped loads using either the exponential, polynomial, or comprehensive model. A generic load model expresses the characteristics of the load at any instant of time as algebraic functions of the bus voltage magnitude and frequency at that instant. Refer to section 8.12 for more information.

Modeling of AC-DC Converters In a Load Flow Study, chargers and UPS’s are represented as constant kVA loads connected to their AC input bus. An inverter is represented as a swing machine, which can maintain its terminal bus angle and voltage magnitude constant. If you have more than one inverter connected to a bus, they will equally share the load. ETAP uses the efficiency of the the Variable Frequency Drive to calculate calculate the losses of the VFD. VFD. Losses associated with VFDs are included as part of the connected load.

Modeling of HV DC’s In a Load Flow Study, the HV DC link is represented as a branch, which consists of a Rectifier, a DC line, and an Inverter. Both the Inverter and the Rectifier of the HVDC link require a connection either directly to a swing bus or to a system containing a swing bus.

Modeling of SVC’s In a Load Flow Study, the SVC is represented as a variable static load. The SVC regulates voltage at its terminal by controlling the amount of reactive power injected into or absorbed from the power system. When running load flow on a system containing an SVC, load flow will first determine the system voltages without the SVC. If the initial voltage of the bus connected to SVC is lower than the reference voltage, the SVC will inject reactive power. And if the initial voltage of the bus connected to SVC is higher than the reference voltage, the SVC will absorb reactive power. Refer to section 11 for more information.

Different Factors Considered in Load Calculation ETAP provides you with great flexibility in modeling load variations through different load factors, such as demand factor, load percent, service factor, and application factor, etc. Depending on your specifications, these factors are used differently in calculating loads under several circumstances:

•

Load Editor – Calculation of load for loading categories and voltage drop

•

Input for Studies – Calculation of load specification for load flow and initial load for motor starting and transient stability studies

•

Studies Results – Calculation of load displayed in one-line diagram from load flow, motor starting, and transient stability studies


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Calculation Methods

Bus Editor – Sum of load connected to a bus

The following two tables describe how these factors are used in these cases:

Factors Used for Motor Load Calculation Load Editor Load Loss Vd

Bus Nominal kV

x

x

Bus Operating V

x

x

Input to Studies Load Loss

x

x

Results from Studies Load Loss Vd

x

x

x

x

x

x

Bus Editor

x

Demand Factor

x

x

x

x

x

x

x

x

x

Loading %

x

x

x

x

x

x

x

x

x

x

x

x

x

Bus Diversity Factor

*

*

*

*

*

Global Diversity Factor

*

*

*

*

*

Service Factor

*

App. Factor

*

Load Quantity

x

x

x

Factors Used for Static Load Calculation Load Editor Load Loss Vd

Bus Nominal kV

x

x

Bus Operating V

x

Input to Studies Load Loss

x

x

x

Results from Studies Load Loss Vd

x

x

x

x

x

x

Bus Editor

x

Demand Factor

x

x

x

x

x

x

x

x

x

Loading %

x

x

x

x

x

x

x

x

x

x

x

x

x

Bus Diversity Factor

*

*

*

*

*

Global Diversity Factor

*

*

*

*

*

App. Factor Load Quantity

* x

x

x

* Indicates the factor is used in calculation if specified by the user in the related Load Editor or Study Case. Notes:

• •

Motor load includes induction motor and generator, synchronous motor, and motor load portion of lumped load. Static load includes static load, capacitor, MOV, and static load portion of conventional and unbalanced lumped loads.


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Calculation Methods

19.5 Panel System Load Flow Calculation When the Calc. Panel/UPS System option is checked in the Study Case, the panel/UPS system load flow will be carried out along with the 3-phase system in a load flow run. Due to special conditions for panel/UPS systems, the calculations are performed with a different method from the one used for the 3 phase system. When the Calc. Panel/UPS System option is not checked in the Study Case, loads from a panel/UPS system is summed up for the specified load category to the top element (a panel, a phase-adaptor, or an UPS) of the panel/UPS system and this top element is treated as a load to the 3-phase system. In this load summation, loads are added up under rated voltage without considering losses and voltage drop.

Panel/UPS Systems A panel system is defined as a radial sub-system that is powered through a top panel, a phase adaptor, or an UPS connected to a 3-phase bus. A power system may contain several panel systems. Each panel system has a top element that is either a 3-phase panel or a phase adapter.

Special Conditions for Panel System Load Flow Calculation Looped Panel System A panel system should be a radial sub-system. There should be no loops involved. Before load flow calculation, ETAP checks for loop configurations. In case any loops are detected in a panel system, an error will be posted.

Transformer LTC Transformer LTC is not considered for any transformer in panel systems. Even if the LTC field is checked in the Transformer Editor, it will be ignored in panel load flow calculation.

Branch Shunt Impedance Shunt impedance for branches such as cable, transmission line, and impedance are not included in the panel system load flow calculation.

Feeder Cable for Panel Internal Loads In the load flow calculation, internal loads for a panel are lumped into an equivalent load. As a result, losses caused by feeder cables of panel internal loads are not considered in panel system load flow calculation. However, feeder cables for external loads are included in the calculation.

Calculation Method The panel system load flow calculation is carried out sequentially with 3-phase load flow to achieve accurate result. The calculation involved three stages. Before the 3-phase system load flow calculation is performed, a load flow computation is carried out for each panel system for the loading category and diversity factors specified in the study case. In this computation, the terminal bus voltage of the top element is assumed to be fixed at its initial value entered in the Bus Editor. The purpose of this pre-load-flow calculation is to accurately calculate panel system load, including branch losses and effect of voltage drop on various types of loads.


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Calculation Methods

Once the panel system load is calculated, it is stored in the top element. The 3-phase system load flow calculation is then carried out, in which the top element of each panel system is represented as a single load connected to a 3-phase bus. After the 3-phase system load flow is completed, a load flow calculation is carried out again for each panel system with the updated terminal bus voltage of the top element just calculated from the 3-phase system load flow. The results of the calculation are reported on the one-line diagram and in Crystal Report.


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Load Flow Analysis

Required Data

19.6 Required Data Bus Data Required data for load flow calculations for buses includes:

• Nominal kV • %V and Angle (when Initial Condition is set to use Bus Voltages) • Load Diversity Factor (when the Loading option is set to use Diversity Factor)

Branch Data Branch data is entered into the Branch Editors, i.e., Transformer, Transmission Line, Cable, Reactor, and Impedance Editors. Required data for load flow calculations for branches includes:

• • • •

Branch Z, R, X, or X/R values and units, tolerance, and temperature, if applicable Cable and transmission line, length, and unit Transformer rated kV and kVA/MVA, tap, and LTC settings Impedance base kV and base kVA/MVA

Power Grid Data Required data for load flow calculations for power grids includes:

• Operating Mode (Swing, Voltage Control, Mvar Control, or PF Control) • Nominal kV • %V and Angle for Swing Mode • %V, MW loading, and Mvar limits (Q max & Qmin) for Voltage Control Mode • MW and Mvar loading, and Mvar limits Mvar Control Mode • MW loading and PF, and Mvar limits for PF Control Mode

Synchronous Generator Data Required data for load flow calculations for synchronous generators includes:

• • • • • •

Operating Mode (Swing, Voltage Control, or Mvar Control) Rated kV %V and Angle for Swing Mode of Operation %V, MW loading, and Mvar limits (Q max and Qmin) for Voltage Control Mode MW and Mvar loading, and Mvar limits Mvar Control Mode MW loading and PF, and Mvar limits for PF Control Mode

Note: The Mvar limits (Qmax and Qmin) can also be calculated from the capability curve. The required additional data for this calculation includes:

• •

All data on the Capability page Synchronous reactance (X d )


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Load Flow Analysis

Required Data

Inverter Data Required data for load flow calculations for inverters includes:

• • •

Inverter ID DC and AC rating data AC output voltage regulating data

Synchronous Motor Data Required data for load flow calculations for synchronous motors includes:

• • • •

Rated kW/hp and kV Power factors and efficiencies at 100%, 75%, and 50% loadings % Loading for desired Loading Category Equipment cable data

Induction Motor Data Required data for load flow calculations for induction motors includes:

• • • •

Rated kW/hp and kV Power factors and efficiencies at 100%, 75%, and 50% loadings % Loading for desired Loading Category Equipment cable data

Static Load Data Required data for load flow calculations for static loads includes:

• • • • •

Static Load ID Rated kVA/MVA and kV Power factor % Loading for desired Loading Category Equipment cable data

Capacitor Data Required data for load flow calculations for capacitors includes:

• • • •

Capacitor ID Rated kV, kvar/bank, and number of banks % Loading for desired Loading Category Equipment cable data


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Load Flow Analysis

Required Data

Lumped Load Data Required data for load flow calculations for lumped loads includes: Conventional • Load ID • Rated kV, kVA/MVA, power factor, and % motor load • % Loading for desired Loading Category Unbalanced • Load ID • Rated kV, kVA/MVA, power factor, % motor load, and % static load • % Loading for desired Loading Category Exponential • Load ID • Rated kV, P0, Q0, a, and b • % Loading for desired Loading Category Polynomial • Load ID • Rated kV, P0, Q0, p1, p2, q1, and q2 • % Loading for desired Loading Category Comprehensive • Load ID • Rated kV, P0, Q0, a1, a2, b1, b2, p1, p2, p3, p4, q1, q2, q3, and q4 • % Loading for desired Loading Category

Charger and UPS Data Required data for load flow calculations for chargers and UPS’s includes:

• • •

Element ID Rated AC kV, MVA, and power factor, as well as DC rating data % Loading for desired Loading Category

HV DC Link Data Required data for load flow calculations for HV DC links includes:

• • •

Element ID All data on the Rating page is required for Load Flow calculations Inverter current margin (I m)


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Load Flow Analysis

Required Data

SVC Data Required data for load flow calculations for SVC’s includes:

• • • • • •

Element ID Rated kV Inductive Rating (Either Q L, IL, or BL) Capacitive Rating (Either Q C, IC, or BC) Max Inductive Rating (Either Q L(Max), or IL(Max)) Max Capacitive Rating (Either Q C(Min), or IC(Min) )

Note: QC, QC(Min), and BL must be entered as a negative value

Panel Data Required data for load flow calculations for panels includes:

• Element ID • Rated kV and Amps • Number of Branch Circuits • Loading and %Loading • Phasing, Number of Poles, and State • Connection Type, i.e. Internal, External, Spare, etc.

Other Data There are some Study Case related data, which must also be provided. This includes:

• • • • • • • •

Method (Newton-Raphson, Fast-Decoupled, or Accelerated Gauss-Seidel) Max Iteration Precision Acceleration Factor (when Accelerated Gauss-Seidel Method is selected) Loading Category Initial Voltage Condition Report (report format) Update (for bus voltages and transformer LTCs using load flow result)

The Study Case related data is entered into the Load Flow Study Case Editor.


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Load Flow Analysis

Output Reports

19.7 Output Reports The load flow calculation results are reported both on the one-line diagram and in the Crystal Reports format. The graphical one-line diagram displays the calculated bus voltages, branch flows and voltage drops, load power consumption, etc. You can use the Display Options Editor to specify the content to be displayed. It also flags abnormal operating conditions, such as overloaded cables and over- or under voltage buses, in different colors. The Crystal Reports format provides you with detailed information for a Load Flow Analysis. You can utilize the Load Flow Report Manager to help you view the Output Report.

19.7.1 View from Study Case Toolbar This is a shortcut for the Report Manager. When you click on the View Output Report button, ETAP automatically opens the Output Report listed in the Study Case toolbar with the selected format. In the picture shown below, the Output Report name is LF 100A and the selected format is Complete.

19.7.2 Report Manager To open the Report Manager, simply click on the Report Manager button on the Load Flow toolbar. The editor includes four pages (Complete, Input, Result, and Summary) representing different sections of the output report. The Report Manager allows you to select formats available for different portions of the report and view it via Crystal Reports. There are several fields and buttons common to every page, as described below.

Output Report Name This field displays the name of the output report you want to view.


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Load Flow Analysis

Output Reports

Path This field displays the name of the project file based on which report was generated, along with the directory where the project file is located.

Help Click on this button to access Help.

OK/Cancel Click on the OK button to close the editor and open the Crystal Reports view to show the selected portion of the Output Report. If no selection is made, it will close the editor. Click on the Cancel button to close the editor without viewing the report.

19.7.3 Complete The Complete Report includes Input Data, Results, and Summary Reports.

Viewer and File Options You can view the report in the Crystal Reports viewer, or save the report in PDF, MS Word, Rich Text Format, or Excel format. If you wish this selection to be the default for reports, click the Set As Default checkbox.


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Output Reports

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Output Reports

19.7.4 Input Data This page allows you to select different formats for viewing input data, grouped according to type. They include: Adjustments Branch Bus Cable Cover Equipment Cable High Voltage DC Link Impedance Line Coupling NO Protective Devices Reactor SVC Transformer


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Output Reports

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Output Reports

19.7.5 Results This page allows you to select the desired Output Report.


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Output Reports

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Output Reports

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Output Reports

19.7.6 Summary This page allows you to select different portions of the load flow summary to view. Note: Some portions of the summary are available only when you have selected specific options in the study case, such as Critical and Marginal Voltage options.

Alert-Complete Alert-Critical Alert-Marginal Branch Loading Bus Loading Losses Summary


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Output Reports

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Load Flow Analysis

Alert View

19.8 Alert View The functional objective of the Alert View is to provide an immediate list of all the alerts generated by the load flow calculation. The Alert View window may be configured to automatically display as soon as the load flow calculation is over by selecting the Auto Display checkbox in the Alarm page of the Load Flow Study Case. It may also be accessed by a left-click on the Alert View icon. The Alert View provides several tabulated sections of information about the reported alerts. You may refer to Section 15.2.3 Alert page for detailed information on alerts for each type of elements.

Device ID The Device Identification group of the Alert View lists the names of all the components that qualified as alerts after the load flow calculation.

Type The Type group of the Alert View displays information about the type of the device having the displayed alert.

Condition The Condition group of the Alert View provides a brief comment about the type of alert being reported. In the case of load flow alerts, the different conditions reported are Overloads, Over Voltage, Under Voltage, Over Excited, and Under Excited.


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Rating/Limit The Rating group of the Alert View provides the rating information being used by the Load Flow Module to determine whether an alert should be reported and of what kind. Section 15.2.3 Alert Page provides detailed information on alerts for each type of elements.

Operating The Operating group of the Alert View displays the results from the Load Flow calculation. The results listed here are used in combination with those displayed in the ratings section to determine the operating percent values. These values are then compared to those entered in the Alert page of the Load Flow Study Case Editor.

%Operating This group displays the percent operating values calculated based on the load flow results and the different element ratings/Limits. The values displayed here are directly compared to the percent of monitored parameters entered directly into the Alert page of the Load Flow Study Case Editor. Based on the element type, system topology and given conditions, the Alert Simulation program uses these percent values to determine if and what kind of alert should be displayed.

Phase Type This group displays whether the alert being displayed is for a Single-Phase or 3-Phase component.


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Result Analyzer

19.9 Load Flow Result Analyzer The Load Flow Result Analyzer allows you to view the results of various load flow studies in one screen so you can analyze and compare the different results. You can compare the results of general information about the project or more specific information such as the results contained from buses, branches, loads or sources in a load flow study. The Load Flow Result Analyzer is a time saving tool that allows you to compare and analyze different reports coming from different projects, within the same directory, in a single display.

Export Export Load Flow Analyzer Data and create a report in Microsoft Excel format.


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19.9.1 Report and Result Selections Study Reports: Select which Load Flow Study Reports to compare by clicking on the checkbox. The results of the selected study report(s) will appear in the display table.

Ref

Select the study report that is used as the reference. The Display table also indicates which study report is used as the reference by a green highlight on the study report name.

Report Type Select which Report Type you would like displayed.


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General Info Selecting General will display the general information contained in the study report such as number of elements, system generation, loads and losses, and conversion parameters. Bus Results Selecting Bus will display the bus information contained in the study report. Branch Results Selecting Branch will display the branch information contained in the study report. Loads Selecting Load will display the load information contained in the study report. Sources Selecting Source will display the source information contained in the study report.

Project Report Select which project report(s) you would like active.

Active Project The first selection is defaulted to the open project file. This will limit you to all the reports generated from this project. All Projects in Active Directory This allows the user to compare reports from different projects that are located within the directory that the current (open) project file resides.


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19.9.2 General Info Under this category, general information that summarizes the study and the information that is reported in the first and last page of the output reports are displayed. When “General Info” is selected, the Display Table is changed to show the following:

Study Case ID Study case ID: unique name up to 25 characters. Data Revision This field indicates the name of the Data Revision used for the selected study report. Configuration This field indicates the configuration status being used for the selected study report. Loading Cat Display the name of the Loading Category used for the selected study report. Generation Cat Display the name of the Generation Category used for the selected study report. Diversity Factor Display the Load Diversity Factor used for the selected study report. Buses Display the total number of Energized Buses that exist in the selected study report.


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Branches Display the total number of Branches that exist in the selected study report. Generators Display the total number of Generators that exist in the selected study report. Power Grids Display the total number of Power Grids that exist in the selected study report. Loads Total number of Loads that exist in the selected study report. Load-MW Total Load in MW that exists in the selected study report. Load-Mvar Total Load in Mvar that exists in the selected study report. Generation-MW Display the total Generation in MW that exists in the selected study report. Generation-Mvar Display the total Generation in Mvar that exist in the selected study report. Losses-MW Display the total losses in MW that exist in the selected study report. Losses-Mvar Display the total losses in Mvar that exist in the selected study report. Mismatch-MW Display the total mismatch in MW that exists in the selected study report. Mismatch-Mvar Display the total mismatch in Mvar that exist in the selected study report.


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19.9.3 Bus Results Under this category, bus information and the load flow results for the buses are displayed. When “Bus Results” is selected, the Result Analyzer display is changed to show the following:

Bus Type This section determines what type of buses to display in the table.

Source Buses These are Buses that are connected to a Generator or Power Grid. Nodes These are Buses that have been graphically displayed as Nodes.


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MCC & SWGR These are Buses that have MCC or SWGR as the type selected in the Rating page. Load Buses Buses that have loads connected to them.

Bus Info This section determines which bus information to display in the table.

Nominal kV Display the bus nominal voltage in kV of the selected bus. Amp Rating Display the ampere rating of the selected bus. Type Display the bus type information: Gen, SWNG, or Load.

Unit This section determines the measurement unit used to display the bus loading results and operating bus voltages.

Load Flow Results This section determines which results to display in the table. Note: When multiple study reports are selected, Calculated Results section becomes Radial buttons.


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Voltage Display operating voltage based on the result voltage unit (kV, % of Bus nominal kV, or Volts). kW Loading Display total bus loading (kW or MW). kvar Loading Display total bus loading (kvar or Mvar). Amp Loading Display Ampere Loading of the load directly connected to the bus. % Loading Displays the percent loading based on the calculated ampere loading and ampere rating of the bus.

Alert This section allows you to enter the marginal and critical limits on the display table. Note: The results will be highlighted based on these limits, not based on the limits set from the study case.

Loading Highlights bus loading alerts. OverVoltage Highlights bus over voltage alerts.


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UnderVoltage Highlights bus under voltage alerts.

Display Options

Actual Value Display the actual value of the results. Differences with Ref. Display the delta differences between the calculated results with respect to the values from the reference report. Skip if Same Data that has the same results as the reference study will not be displayed.

Find Select any bus from the Bus ID list and click find to locate that bus on your one-line diagram.


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19.9.4 Branch Results: Under this category, branch information and the load flow results for the branches are displayed. When “Branch Results” is selected, the Result Analyzer display is changed to show the following:

Branch Type Select the Branch type(s) to display on the table. The list of branch types is below:

• • • • • •

Transformer Cable Line Reactor Impedance Equipment Cable

Branch Info This section determines which branch information to display in the table.


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From Bus Display “From Bus” connection for that element. To Bus Display “To Bus” connection for that element. Type Display the element type on the display table. Rating 1 and Rating 2 Display the Rating for each branch. See table below for each Rating: Type 2-W Transformer 3-W Xfmr Primary 3-W Xfmr Secondary 3-W Xfmr Tertiary Cable Line Reactor Impedance

Equipment Cable

Rating 1 Primary kV / Secondary kV Rated kV Rated kV Rated kV Length Meters Length Meters Positive sequence impedance ohms Positive sequence resistance ohms/percent Length Meters

Rating 2 Primary Winding Rating MVA/kVA Primary Winding Rating MVA/kVA Primary Winding Rating MVA/kVA Primary Winding Rating MVA/kVA Size Size Reactor rating Amps Positive sequence reactance ohms/percent Size

Unit This section determines the measurement unit used to display the branch loading results and operating branch voltages.



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kW Flow Display power flow (kW or MW) kvar Flow Display power flow (kvar or Mvar) Amp Flow Display ampere flow from one bus to another. % PF Display Power Factor (%) % Loading Display loading (%) % Voltage Drop Display voltage drop (%) kW Losses Display branch losses (kW or MW) kvar Losses Display branch losses (kvar or Mvar)

Alert This section allows you to enter the marginal and critical limits on the display table. Note: The results will be highlighted based on these limits, not based on the limits from the Study Case.

Loading Highlight branch loading alerts.


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Voltage Drop Highlight branch voltage drop alerts.

Display Options


Find Select any branch from the ID list and click find to locate that element on your one-line diagram.


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19.9.5 Loads Under this category, load information and the load flow results for the loads are displayed. When “Loads” is selected, the Result Analyzer display is changed to show the following:

Load Type Select the load type(s) to display on the table. The list of load types is below:

• • • • • • • •

Induction Synchronous Lumped Static MOV Capacitor SVC Filter

Load Info This section determines which load information to display in the table.


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Terminal Bus Bus connected to the load. Type Display the load type on the display table. Rating and Rating kV Display the Rating for each load. See table below for each Rating: Type Induction Synchronous Lumped Static MOV Capacitor SVC Filter

Rating

HP/ kW HP/ kW MVA/kVA MVA/kVA HP/kW Capacitor rated Mvar/kvar Rated inductive/capacitive var kvar/Mvar Capacitor rated Mvar/kvar per phase

Rating kV Rated voltage Rated voltage Rated voltage Rated voltage Rated voltage Rated voltage Rated voltage Rated voltage

Unit This section determines the measurement unit used to display the operating load and load terminal voltage results.



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kW Loading Total operating load (kW or MW) kvar Loading Total operating load (kvar or Mvar) Amp Loading Display the current loading results. % PF Display the Power factor (%). % Loading Displays the percent loading based on the calculated ampere loading and ampere rating of the load. Terminal Voltage Display the load terminal voltage results.

Alert This section allows you to enter the marginal and critical limits on the display table. Note: The results will be highlighted based on these limits, not based on the limits from the study case.

Loading This highlights loading alerts for loads. OverVoltage This highlights over voltage alerts for loads. UnderVoltage This highlights under voltage alerts for loads.


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Display Options


Find Select any load from the ID list and click find to locate that load on your one-line diagram.


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19.9.6 Sources Under this category, source information and the load flow results for the sources are displayed. When “Sources” is selected, the Result Analyzer display is changed to show the following:

Source Type Select the Source type(s) to display on the table. The list of source types is below:

• • •

Power Grid Synchronous Wind Turbine

Source Info This section determines which source information to display in the table.


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Terminal Bus Display the bus connected to the source. Type Display the source type. Rating and Rating kV Display the ratin g for each source. See table below for each Rating: Type Power Grid Synchronous Wind Turbine

Rating 3 phase Short Circuit MVAsc Contribution Rated Real Power MW/ kW Rated Real Power MW/kW

Rating kV Rated voltage Rated voltage Rated voltage

Unit This section determines the measurement unit used to display the total operating source generation and the rating for each source.


kW Generation Total operating source generation (kW or MW). kvar Generation Total operating source generation (kvar or Mvar). Amp Source current results


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% PF Power factor of the source (%) % Generation Source generation (%)

Display Options

Actual Value Display the actual value of the results. Differences with Ref. Display the delta differences between the calculated results with respect to the values from the reference report. Skip if Same Data that has the same results as the ref erence study will not be displayed.

Find Select any source from the ID list and click find to locate that source on your one-line diagram.


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19.10 Load Analyzer The Load Analyzer module is designed as a generalized load-list to report load-schedules for power system components such as switchgear, MCC, transformers, cables, lines, panels, etc. Different reports provide informative data regarding all loads connected downstream to equipments. This tool is helpful during the operating phase of a project, as well as design/planning phase where system studies may not be possible due to incomplete one-line diagram or data. Reports include the following user options: 1. 2. 3. 4. 5. 6. 7. 8.

Base or Revision Data Configuration Loading Category Connected / Operating Loads Continuous / Intermittent / Spare Loads Continuous / Non-Continuous Loads Load Demand Factors Global and Individual Bus Diversity (Deviation) Factors

In addition and in contrast with the regular Load Flow analysis, the Load Analyzer allows a deeper study of the different loads present in a system. This gives the user more flexibility in analyzing individual loads using Minimum/Maximum Bus Loading, or to simply determine the actual connected and operating loads in a given system. Notes:

• • • • •

Looped configurations or systems with two swing sources (utility or generator) are not currently handled by the Load Analyzer. Only radial systems are handled. In case the load voltage from the nameplate of an element is different from the upstream Bus voltage, the Load Analyzer will not adjust the voltage of the element. Therefore, the Load Analyzer results will be different from the Load Flow results. Wind turbines, MG sets, Harmonic Filters (HF), and Static var Compensators (SVC) loads are not considered by the Load Analyzer. These loads will be added in the future. 3-phase and 1-phase loads below an Uninterruptible Power Supply (UPS) are not considered by the Load Analyzer. Only the internal load of the UPS is considered. Feeder losses and branch losses are ignored by the Load Analyzer. The Load Flow program considers all branch losses.

19.10.1 Load Analyzer Editor The Load Analyzer module is launched from the Load Flow mode and by clicking on the Load Analyzer icon, which is located on the right hand side toolbar.


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Once the module is launched, the Load Analyzer Editor opens. Following is a list and description of the different fields available in this editor.

Project The project name is displayed in this field. This filed is for your information and cannot be edited.


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Revision The project revision is displayed in this field. This field is for your information and cannot be edited. To change the revision you must close this editor, go to the Revision toolbar and select another revision.

Configuration The project configuration is displayed in this field. This field is for your information and cannot be edited. To change the configuration you must close this editor, go to the Configuration toolbar and select another configuration.

Output File Name Enter the output report database filename. By default, ETAP enters the same name as the project name. The output file name can contain upto 250 characters. Note: Very long filenames can cause text wrapping on the report headers and affect the report format. It is recommended to use up to 25 characters for the filename.

Loading Category Select one of the ten Loading Categories for the current Load Analyzer study. With the selection of any category, ETAP uses the percent loading of individual motors and other loads as specified for the selected category. Note that you can assign loading to each one of the ten categories from the Nameplate page of the induction machine and synchronous motor editors and the Loading or Rating page of other load component editors.


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Load Diversity Factor In the Load Analyzer editor, you can choose the desired Load Diversity Factor applied to each of the three Demand Factors for each load (i.e. Continuous, Intermittent, and Spare). The different Load Diversity Factors are the following:

• None (no load diversity factor is applied) • Bus Max (individual Bus Max diversity factor is applied to directly connected loads) • Bus Min (individual Bus Min diversity factor is applied to directly connected loads) • Global Value (Global load diversity factor is applied to all loads) For each Bus in the system, the user can define the upper and lower bounds of the Load Diversity Factor that will apply to the loads directly connected to that Bus. These individual Load Diversity Factors are applied when Bus Max or Bus Min is selected from the Load Analyzer editor under each category Continuous, Intermittent, and Spare. These values will not be taken into account for loads since Load Diversity Factors are set to a Global Value. For instance, if the user selects Continuous Load to have a Global Value equal to 90%, then all Continuous Loads in the system will be multiplied by that unique Global Value.

Demand Factor In ETAP, operation of loads fall under three status categories:

• • •

Continuous (default is set to 100%, which means the load operates continuously) Intermittent (default is set to 50%, which means the load operates for 12 hours) Spare (default is set to 0%, which means the load is not operating)

The accounted percentage of the load falling under each category, called the Demand Factor, can be set for individual loads from each editor in the Info page.


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Apply Bus Diversity Factor to Non-Directly Connected Loads The Load Analyzer program allows the user to apply Load Diversity Factor to non-directly connected loads in the system. This means that if the Apply Bus Diversity Factor to Non-Directly Connected Load option is checked, then the Load Diversity Factor of all buses in the system will be considered (i.e. multiple dipping is applied at all levels).

PF & EFF For all induction and synchronous motors in the system, the user can select to either use the Rated Power Factor (PF) and Efficiency of motors, or to use interpolated values for the specified motor % loading. If the Rated PF and/or Eff options are selected, then Rated PF and Eff will be used for synchronous motors, and PF and Eff of 100% loading will be used for induction machines. If the Interpolate at Specified % Loading option is selected, then the program interpolates the Power Factor and Efficiency entered for both induction and synchronous motors at the specified % Loading. The interpolation occurs linearly based on the Power Factor and Efficiency values entered at 100, 75, and 50 % Loadings. The Power Factor and Efficiency values can be entered for individual motors from their editor and Nameplate page.

19.10.2 Reports Once the different settings have been selected from the Load Analyzer interface, click OK and the Load Analyzer Report Manager will open to display the results of the study. The user has the choice to select different reports from the following tabs:


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• • • •

Result Analyzer

Bus Loading Bus Summary Load List Schedules

Report Manager also displays the Output Report Name and the Path where project files are located. As a reminder, Load Analyzer is the only module that skips reporting of nodes in some of its reports. For other ETAP modules, nodes and buses are treated the same way in output reports. Load Analyzer reports can export into Viewer (Crystal Reports format), PDF, MS Word, Rich Text Format, and MS Excel and allows choosing any of these formats to be Set As Default. For the Load Analyzer reports, ETAP creates Access databases with the extension of .LA1. This database is used to produce load analyzer output reports. All reports include a header, which displays project name, business location, contract number, the engineer’s name, filename, ETAP logo, ETAP version number, report name, page number, date, serial number (SN), revision number, configuration, and remarks with up to 120 characters. The project name, location, contract number, engineer’s name, and remarks can be set from the ETAP toolbar Project/Information. The filename is set in the Output Filename given in the Load Analyzer Editor.

Bus Feeder (FDR) Loading Reports The Bus FDR Loading-1, 2 & 3 reports are sorted alphabetically by Bus ID.


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Bus FDR Loading-1 Report selected from Bus Loading tab in the Report Manager


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Bus Loading Summary Reports The Bus Loading Summary-1 & 2 reports provide the sum of all loads for all Buses including Connected and Operating Loads. These reports are sorted alphabetically by Bus ID.

Bus Loading Summary-1 report selected from Bus Summary tab of the Report Manager


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Bus Loading Summary-2 report selected from Bus Summary tab of the Report Manager

Load List Reports The Load List reports provide load information ordered by Bus Loading Summary, by Bus, by Status, and by Load. As a note, Panels are not included in Load List by Status Report. These reports are sorted alphabetically by Bus ID.


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Load-List Bus Summary report selected from Load List tab of the Report Manager

Load-List by Bus report selected from Load List tab of the Report Manager


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Load-List by Status report selected from Load List tab of the Report Manager

Load-List report selected from Load List tab of the Report Manager


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Schedule Reports The Bus Loading Schedule report displays the total load at each Bus including the effect of all multiplying parameters (i.e. % Loading, Demand Factor, and Load Diversity Factor). This Report tabulates only downstream Buses and Loads (no equipment). This report is sorted by Bus kV first and then Bus ID. The Cable Schedule Report tabulates all Equipment and Branch Cables present in the system. This report also provides information about the Connected Buses, kV, and other physical parameters for each Cable. Transformer Loading Schedule-1 & 2 reports tabulate all Transformers present in the system. These reports also provide information about the Connected Buses, Impedance, and other electrical parameters for each transformer.

Bus Loading Schedule Report selected from Schedules tab of the Report Manager


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Cable Schedule Report selected from Schedules tab of the Report Manager

Transformer Loading Schedule-1 report selected from Schedules tab of the Report Manager


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