The anatomy of a substation

In the Heart of Wind Farm Country


We joined our Training Program Manager, Steve Newton, at a substation training simulator in the heart of wind farm country in west Texas, to discuss the different parts of a generation substation.

Most substations step high voltage circuits down to a usable voltage that can be distributed to consumers. However, this simulator is based on a generation substation which would take 34.5 kV circuits from the wind generation strings, distribute them into the station, and send them out at 138 kV to a utility provider.

Steve tells us what each part of the substation is and how it all ties together.

The Relay House

The relay house is the control center for the entire switch yard. The breakers, motor operators and circuit switchers can be controlled from here.




This is where the 34.5 kV generation comes into the substation from the wind generators. There are two circuits with different types of circuit breakers. These two breakers would isolate two separate feeds from an entire string of wind generators, which will later be stepped up to 138 kV by a transformer.



34.5 kV Circuit Switcher

The 34.5 kV circuit switcher isolates three large inductors or reactors, which are used for system voltage conditioning. They can also affect the different aspects of the system they are tied to, depending on their application. The circuit switcher will lead into a capacitor bank through overhead bus work and feed into the 34.5 kV ABB gas circuit breaker.



34.5 kV ABB Gas Circuit Breaker

This breaker is the secondary breaker to the rest of the 34.5 kV system.



138 kV Siemens SF6 Circuit Breaker

This circuit breaker is used to isolate the circuit in case of a fault. From this breaker, it would go to a transformer which would step the system up from 34.5 kV to 138 kV.



Motor Operated Disconnect

The motor operated switch is the last point before the 138 kV exits the station to tie into the grid. It has a single shaft linkage, and it can be manually or electrically operated. This is done through a complex control system that technicians have to be capable of setting up, proofing and aligning.



National Knows Protection & Control

National Field Services has years of experience with both new and retrofit power system protection and control services, including turnkey engineering services.

Our accredited technicians and professional engineers can help improve your system reliability and personnel safety by making sure you are getting the full benefits of your protection equipment. To learn more about what National can do for you, contact us!