Basic Substation Training
By Kelvin Tang 4 June 2009
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Basic Substation Training
•Basic substations •Why do we need them? •Different configurations •Availability •Design parameters •Function of main components •Cost drivers
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Basic Substation Training What is a Substation? SUBSTATION - A facility that steps up or steps down the voltage in utility power lines. Voltage is stepped up where power is sent through long-distance transmission lines. It is stepped down where the power is to enter local distribution lines. - California Energy Commission Dictionary An electricity substation is a place, which allows electricity to go from one part of the production system to another. Cambridge International Dictionary Subsidiary station in which electric current is transformed. Merriam Webster’s Dictionary ABB
Basic Substation Training What is a Substation? Outdoor Substation is an open type of structure for supporting high-voltage air-insulated power equipment. – NEMA SG 6
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Basic Substation Training Why do we need a substation? Substations are entities that integrate the power system (Generation, Transmission, and Distribution). They provide: -Transformation -Switching -Tie Points -Sectionalizing -Protection -Compensation
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Basic Substation Training Design Objective: The substation design objective is to provide maximum reliability, flexibility, and continuity of service and to meet these objectives with the lowest investment costs that satisfy system requirements. – Standard Handbook for Electrical Engineers
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Basic Substation Training Design Considerations: •Voltage Level •Load Capacity •Environmental Considerations •Site Space Limitations •Transmission Line right-of-way Requirements •Safety •Maintenance and Operation •Expandability •Cost •Reliability
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Basic Substation Training Types of Substations: •AIS – Air Insulated Substation •GIS – Gas Insulated Substation •Hybrid – SF6 and Air •Modular Substation •Standard Substation •Mobile Substation •Distribution Substation (34-138 kV HV; 2.4-34.5 kV LV side) •Transmission Substation (230-745 kV HV; 34-230 kV LV side) •Switching Substation (Transmission SS without transformer)
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Basic Substation Training Types of Substations: AIS Advantages Easy access to bus and equipment for inspection and repair Lower cost Design and material flexibility Easy to expand Easy to replace equipment
Disadvantages Equipment are subject to weather conditions, animals, vandalism, contamination Requires more real estate
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Basic Substation Training Types of Substations: AIS
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Basic Substation Training Types of Substations: GIS Advantages Reduced space requirements Less exposure to contamination HV Bus physically protected Flexible layout and Expansion No concern about clearances to ground Can be installed indoors
Disadvantages Higher cost Requires clean work area for assembly Expensive repair Requires special training for operators Spare parts are specialized
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Basic Substation Training Types of Substations: GIS
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Basic Substation Training Configurations of Substations: •Single Bus •Segmented Single Bus (Single Bus with Sectionalizer) •Main and Transfer Bus •Double Bus, Single Breaker •Double Bus, Double Breaker •Ring Bus •Breaker and a Half
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Basic Substation Training Configurations of Substations: Single Bus Advantages Least cost Expandable Simple protection scheme Simple operation Less real estate requirements
Disadvantages Bus fault causes a complete substation outage Minimal flexibility for maintenance Expansion requires complete outage
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Basic Substation Training Configurations of Substations: Segmented Single Bus Advantages Disadvantages Higher cost (more breaker / switches / Increased reliability relaying) More operational flexibility (fault on the More equipment to maintain bus will de-energize only half of the SS) Maintenance can be done in one bus while Outage can occur on several lines of the the other is energized. same bus
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Basic Substation Training Configurations of Substations: Main and Transfer Bus Disadvantages Extra circuit breaker
Advantages Circuit breaker can be readily removed from service for maintenance Relatively low cost for increased flexibility Requires a switching procedure for transferring a line to another breaker Increased relaying complexity Failure on the main bus may cause a complete outage of the substation MAIN AND TRANSFER BUS
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Basic Substation Training Configurations of Substations: Double Bus, Single Breaker Advantages Disadvantages One breaker per line Extra breaker for coupling Bus fault or breaker failure will disconnect Provide more flexibility all circuit connected to this bus Tie breaker fault causes outage on the Each bus can be isolated for maintenance entire substation Each circuit can be connected to either bus Complicated switch operation Complicated relaying Requires additional switches
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Basic Substation Training Configurations of Substations: Advantages Each breaker can be serviced without disconnecting the circuit Either bus can be serviced without interruption of power High availability and reliability
Double Bus, Double Breaker Disadvantages Two breaker per circuit Highest cost Possibility of losing half of the substation
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Basic Substation Training Configurations of Substations: Ring Bus Advantages Low cost Each breaker can be maintenance without outages One breaker per circuit No main bus During fault only two breaker are tripped During breaker failure three breaker are tripped All switches is done with breakers
Disadvantages Fault during a breaker maintenance causes a ring separation Automatic reclosing and protective relaying rather complex Requires a potential transformer in each circuit Difficult expansion RING BUS
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Basic Substation Training Configurations of Substations: Advantages Most flexible operation High reliability Bus breaker failure removes only one circuit Bus failure causes no outage All switching done with breakers Simple operation Either bus can be taken out of service High availability
Breaker and a half Disadvantages High cost More breakers Complex reclosing and protection schemes
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Basic Substation Training Availability of a Substation: AVAILABILITY. Describes the reliability of power plants. It refers to the number of hours the Turbines are available to produce power divided by the total hours in a year. - The Sun's Joules Is the percent of the time that a unit is available to produce power whether needed by the system or not. It is a measure of overall unit reliability. It is equal to 100% less percentage of time of forced outage less percentage of time on scheduled outage. – Standard Handbook for Electrical Engineers
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Basic Substation Training Reliability of a Substation: Reliability Engineering. The probability that a product will be operational after a period of usage or over a specified time period, based on testing of the product under a prescribed operation and operating environment – Harcourt Dictionary
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Basic Substation Training Reliability of a Substation: RELIABILITY - Electric system reliability has two components: adequacy and security. Adequacy is the ability of the electric system to supply the aggregate electrical demand and energy requirements of the customers at all times, taking into account scheduled and unscheduled outages of system facilities. Security is the ability of the electric system to withstand sudden disturbances such as electric short circuits or unanticipated loss of system facilities. Energy Terms Dictionary
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Basic Substation Training Reliability of a Substation: System reliability consists of two elements: dependability and security. Dependability is the certainty of correct operation in response to system trouble, whereas security is the ability of the system to avoid misoperation with or without faults. Dependability can be checked relatively easily in the laboratory or during installation by simulated tests or a staged fault. Security, on the other hand, is much more difficult to check. A true test of system security would have to measure response to an almost infinite variety of potential transients and counterfeit trouble indications in the power system and its environment. A secure system is usually the result of a good background in design, combined with extensive model power system and can only be confirmed in the power system itself and its environment. – ABB Protective Relaying Theory and Applications
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Basic Substation Training Why High Voltage Product? -High voltage products perform different important functions in the power system. -Connect, Detect, Protect and Correct: -connect the various parts in a substation. -Detecting & monitor the operating levels of current and voltage for accurate energy measurement. -protect the power system. -correct the voltage and power factor.
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Basic Substation Training Components of a Substation: Circuit breakers: Protects and isolates the power system from faulted lines and equipment. Has the ability of operate under load
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Basic Substation Training Components of a Substation: Disconnect Switches: Provides a visual means of isolating a circuit. Usually operated without load
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Basic Substation Training Components of a Substation: Grounding Switches: Provides a path from phase to ground
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Basic Substation Training Components of a Substation: Current Transformers: Device used for measuring the primary current of the system
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Basic Substation Training Components of a Substation: Potential Transformers: Device used for measuring the primary voltage of the system
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Basic Substation Training Components of a Substation: Coupling Capacitors Voltage Transformer: Device used for measuring the primary voltage and sometimes also in conjunction with the Line Trap for telecommunication applications
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Basic Substation Training Components of a Substation: Line Traps: Used in Power Line Carrier application for telecommunication between substations
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Basic Substation Training Components of a Substation: Lightning Arresters and/or gaps: Device that provides a controlled point for diverting a surge or overvoltage, thereby protecting equipment
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Basic Substation Training Components of a Substation: Power Transformers: Provides transformation of electric power from one voltage level to another at constant power
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Basic Substation Training Components of a Substation: Shunt reactors: Used on long transmission line systems to limit the voltage during breaker operation
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Basic Substation Training Components of a Substation: Current-limiting Reactors: Used to limit the short circuit level of a sub-transmission system
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Basic Substation Training Components of a Substation: Station buses and insulators: Used to route the electrical energy within the SS
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Basic Substation Training Components of a Substation: Grounding System: Protects people and electrical equipment during normal or fault situation, and provides a solid voltage reference point
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Basic Substation Training Components of a Substation: Series Capacitors: Used in EHV systems to increase power flow capacity and system stability
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Basic Substation Training Components of a Substation: Shunt Capacitors: Used for compensating a reactive load and for regulating the voltage
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Basic Substation Training Components of a Substation: Auxiliary Power System: Provides the electricity needed to insure the proper operation of the substation. (Ex.: Auxiliary Transformer, Load Center, Motor Control Center, AC Distribution Panel, DC Distribution Panel, Battery Bank, Battery Charger, etc.)
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Basic Substation Training Components of a Substation: Control and Protection System: Provides means to electrically operate the equipment of a substation from a remote location and also protects the HV equipment in the event of a fault. (Ex.: Protection Relays, Control Panel, Control Panel Accessories e.g., control switches, test switches, indicating lights, etc.)
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Basic Substation Training Design Parameters: Voltage: (V) Term used to designate electrical pressure or force that causes current to flow. – Dictionary of Electronics VOLTAGE. The difference in electrical potential between any two Conductors or between a conductor and ground. It is a measure of the electric energy per electron that electrons can acquire and/or give up as they move between the two conductors. – The Sun’s Joule ABB
Basic Substation Training Design Parameters: Current: Current - The flow of electrons through a complete circuit. – Smart.com Measured in amperes, it is the flow of electrons through a conductor. Also know as electron flow. – Dictionary of Electronics
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Basic Substation Training Design Parameters: Power: Amount of energy converted by a circuit or component in a unit of time, normally seconds. Measured in units of watts. (joules/second). – Dictionary of electronics
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Basic Substation Training Design Parameters: Power: POWER The rate at which energy is consumed or produced. It is expressed in Watts (W). A 1-watt source supplies energy at the rate of 1 Joule per second. (A 100-watt lamp consumes energy at the rate of 100 joules per second; the human body involved in normal activity is rated at about 100W, a significant proportion being used to drive the brain). The Sun radiates energy at the rate of about 70 million watts per square meter of its surface; at the equator the Earth receives a mean annual solar energy flux of around 1,400 watts per square meter. - The Sun’s Joule ABB
Basic Substation Training Civil Design Parameters: Codes: UBC – Uniform Building Code SBC – Standard Building Code BOCA – Building Officials Code Administrators IBC – International Building Code ASCE – American Society of Civil Engineers NESC – National Electrical Safety Code NEMA SG6 – National Electrical Manufacturer Association IEEE – International Electrical and Electronic Engineers Code
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Basic Substation Training Civil Design Parameters: Seismic Zone: Can be measured on: Zone 1, Zone 2, Zone 3, Zone 4 0.1G, 0.2G, 0.3G m/s2 From the “No Seismic” to the “Max Seismic” Zone there may be up to 50% (Breakers and Transformers) difference in the foundation and structural design
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Basic Substation Training Civil Design Parameters: Wind: Old Code: 70-150 mph New Code: 90-180 mph Wind Load = 0.0256 x V2 x factor x S It is the biggest load in a substation structure (except for breakers and transformers)
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Basic Substation Training Civil Design Parameters: Ice: Varies from 0”-1.5” This load can double the normal weight of Conductors and Rigid Buses
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Basic Substation Training Civil Design Parameters: Soil Properties: Soil can vary from a swamp to rocky. The volume of the foundations can vary up to 100% and the cost up to 200% due to these properties
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Basic Substation Training Civil Design Parameters: Water Table: Water must be pumped out of the foundation before pouring concrete on it
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Basic Substation Training
A substation may cost from < 1 million dollars up to tens of millions ABB
Basic Substation Training Acknowledgements: For the support and information sharing, thanks to: • Juliano Braz • Sylvester Phang • Wong Weng Woi • Sankaran-T Arasu
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Basic Substation Training Bibliography: 1. G. Balzer, B. Boehle, K. Haneke, H. G. Kaiser, R. Pohlmann, W. Tettenborn, G. Voss, ABB Switchgear Manual, Tenth Edition 2. W. A. Elmore, ABB Protective Relaying Theory and Applications 3. D. Fink, H. Beaty, Standard Handbook for Electrical Engineers, Thirteenth Edition, McGraw Hill, 1993 4. ABB Power Technologies, High 5, http://www49.de.abb.com/
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