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Basic Substation Training
By Kelvin Tang4 June 2009
ABB
Basic Substation Training
•Basic substations•Why do we need them?•Different configurations•Availability•Design parameters•Function of main components•Cost drivers
ABB
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
ABB
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
ABB
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
ABB
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
ABB
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)
ABB
Basic Substation Training
Types of Substations:
AISAdvantages Disadvantages
Easy access to bus and equipment for inspection and repair
Equipment are subject to weather conditions, animals, vandalism, contamination
Lower cost Requires more real estateDesign and material flexibilityEasy to expandEasy to replace equipment
ABB
Basic Substation TrainingTypes of Substations:
AIS
ABB
Basic Substation Training
Types of Substations:
GISAdvantages Disadvantages
Reduced space requirements Higher costLess exposure to contamination Requires clean work area for assemblyHV Bus physically protected Expensive repairFlexible layout and Expansion Requires special training for operatorsNo concern about clearances to ground Spare parts are specializedCan be installed indoors
ABB
Basic Substation TrainingTypes of Substations:
GIS
ABB
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
ABB
Basic Substation Training
Configurations of Substations:Single Bus
Advantages DisadvantagesLeast cost Bus fault causes a complete substation
outageExpandable Minimal flexibility for maintenanceSimple protection scheme Expansion requires complete outageSimple operationLess real estate requirements
ABB
Basic Substation Training
Configurations of Substations:Segmented Single Bus
Advantages DisadvantagesIncreased reliability Higher cost (more breaker / switches /
relaying)More operational flexibility (fault on the bus will de-energize only half of the SS)
More equipment to maintain
Maintenance can be done in one bus while the other is energized.
Outage can occur on several lines of the same bus
ABB
Basic Substation Training
Configurations of Substations:
MAIN AND TRANSFER BUS
Increased relaying complexity
Main and Transfer BusAdvantages Disadvantages
Circuit breaker can be readily removed from service for maintenance
Extra circuit breaker
Relatively low cost for increased flexibility Requires a switching procedure for transferring a line to another breaker
Failure on the main bus may cause a complete outage of the substation
ABB
Basic Substation Training
Configurations of Substations:
Complicated switch operationEach circuit can be connected to either busComplicated relaying
Tie breaker fault causes outage on the entire substation
Each bus can be isolated for maintenance
Double Bus, Single BreakerAdvantages Disadvantages
One breaker per line Extra breaker for couplingProvide more flexibility Bus fault or breaker failure will disconnect
all circuit connected to this bus
Requires additional switches
ABB
Basic Substation Training
Configurations of Substations:
Possibility of losing half of the substationHigh availability and reliability
Double Bus, Double BreakerAdvantages Disadvantages
Each breaker can be serviced without disconnecting the circuit
Two breaker per circuit
Either bus can be serviced without interruption of power
Highest cost
ABB
Basic Substation Training
Configurations of Substations:
RING BUS
Difficult expansionNo main bus
Requires a potential transformer in each circuit
One breaker per circuit
During fault only two breaker are trippedDuring breaker failure three breaker are trippedAll switches is done with breakers
Ring BusAdvantages Disadvantages
Low cost Fault during a breaker maintenance causes a ring separation
Each breaker can be maintenance without outages
Automatic reclosing and protective relaying rather complex
ABB
Basic Substation Training
Configurations of Substations:
Either bus can be taken out of service
Bus failure causes no outage
Complex reclosing and protection schemesBus breaker failure removes only one circuit
All switching done with breakersSimple operation
High availability
Breaker and a halfAdvantages Disadvantages
Most flexible operation High costHigh reliability More breakers
ABB
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 JoulesIs 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 oftime of forced outage less percentage of time on scheduled outage. – Standard Handbook for Electrical Engineers
ABB
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
ABB
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
ABB
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
ABB
Basic Substation TrainingWhy 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.
ABB
Basic Substation TrainingComponents of a Substation:
Circuit breakers: Protects and isolates the power system from faulted lines and equipment. Has the ability of operate under load
ABB
Basic Substation TrainingComponents of a Substation:
Disconnect Switches: Provides a visual means of isolating a circuit. Usually operated without load
ABB
Basic Substation TrainingComponents of a Substation:
Grounding Switches: Provides a path from phase to ground
ABB
Basic Substation TrainingComponents of a Substation:
Current Transformers: Device used for measuring the primary current of the system
ABB
Basic Substation Training
Components of a Substation:
Potential Transformers: Device used for measuring the primary voltage of the system
ABB
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
ABB
Basic Substation TrainingComponents of a Substation:
Line Traps: Used in Power Line Carrier application for telecommunication between substations
ABB
Basic Substation TrainingComponents of a Substation:
Lightning Arresters and/or gaps: Device that provides a controlled point for diverting a surge or overvoltage, thereby protecting equipment
ABB
Basic Substation TrainingComponents of a Substation:
Power Transformers: Provides transformation of electric power from one voltage level to another at constant power
ABB
Basic Substation TrainingComponents of a Substation:
Shunt reactors: Used on long transmission line systems to limit the voltage during breaker operation
ABB
Basic Substation Training
Components of a Substation:
Current-limiting Reactors: Used to limit the short circuit level of a sub-transmission system
ABB
Basic Substation Training
Components of a Substation:
Station buses and insulators: Used to route the electrical energy within the SS
ABB
Basic Substation TrainingComponents of a Substation:
Grounding System: Protects people and electrical equipment during normal or fault situation, and provides a solid voltage reference point
ABB
Basic Substation TrainingComponents of a Substation:
Series Capacitors: Used in EHV systems to increase power flow capacity and system stability
ABB
Basic Substation TrainingComponents of a Substation:
Shunt Capacitors: Used for compensating a reactive load and for regulating the voltage
ABB
Basic Substation TrainingComponents 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.)
ABB
Basic Substation TrainingComponents 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.)
ABB
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
ABB
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
ABB
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 ofits 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 CodeSBC – Standard Building CodeBOCA – Building Officials Code AdministratorsIBC – International Building CodeASCE – American Society of Civil EngineersNESC – National Electrical Safety CodeNEMA SG6 – National Electrical Manufacturer AssociationIEEE – International Electrical and Electronic Engineers Code
ABB
Basic Substation Training
Civil Design Parameters: Seismic Zone:Can be measured on:Zone 1, Zone 2, Zone 3, Zone 40.1G, 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
ABB
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)
ABB
Basic Substation Training
Civil Design Parameters: Ice:Varies from 0”-1.5”
This load can double the normal weight of Conductors and Rigid Buses
ABB
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
ABB
Basic Substation Training
Civil Design Parameters: Water Table:Water must be pumped out of the foundation before pouring concrete on it
ABB
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
ABB
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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