What is substation commissioning?

Proving the proper operation of a newly
•Repaired piece of equipment before it is placed into service

Several methods for substation commissioning substations provide utilities and developers with ways to effectively maintain project schedules. It is widely known in many industries that testing the entire system, as installed, is the best way to ensure performance and system availability.

Here’s an overview of the key steps in commissioning substation protection systems:

  • Test the entire system as installed
  • Provide load to ensure current transformers have enough current to operate
  • Avoid risk by not having to use customer load
  • Test the entire protection system (because when using the grid for load testing, you may have to bypass some protection)
  • Apply a reactive load if the desire is to test distance relays

Changing the tap settings on a transformer is a common way to provide conditions for testing. Considerations when using this method for transformer commissioning include:

  • Potential damage to transformers from load imbalance
  • Derived load is highly reactive and will not simulate actual conditions for more complex relays
  • Will not properly test distance, directional overcurrent, power directional or other relays that use current and voltage to operate properly
  • Requires multiple relay settings be manually changed or overridden to “force” the system to test the protection relays
  • Metering may need to be bypassed to perform the test
  • Many protection relay faults are not likely to be discovered

When a new substation is constructed or a substation is upgraded, it must be tested before going live. The substation commissioning process involves turning on the facility operations, determining what works, identifying any issues and then fixing problems prior to the operation going on-line. Following established standards and proven processes helps ensure a successful utility substation commissioning.