20 MW utility-scale BESS substation
This utility-scale BESS single line diagram represents a 20 MW storage plant built from two equal battery and PCS blocks. Each 10 MWh DC block connects to a 10 MW power conversion system. Their 690 V outputs meet on a collection bus and are transformed to 34.5 kV for the grid point of interconnection.
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Scenario
A grid-connected storage plant combines two PCS blocks before exporting or importing power through one generator step-up transformer.
Key decisions
- Each 10 MWh battery block has its own 10 MW PCS.
- The PCS outputs combine on a 690 V bus before voltage transformation.
- The 25 MVA GSU provides capacity above the 20 MW nominal conversion rating.
- An intertie breaker and 25/27/81 relay protect the 34.5 kV point of interconnection.
When to reuse this
This pattern suits a modular utility-scale BESS with a collector-system interconnection. The final project requires detailed relay coordination, grounding, and utility telemetry design.
Frequently asked questions
Why are PCS blocks modular?
What is a GSU transformer?
What do 25/27/81 mean?
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