The islanding functionality acts like a system-level fail-safe mechanism, within the customer's power network working in parallel with the utility grid. On detecting a grid fault, it ensures a very swift action to isolate the customer network and prevents it from getting sucked into the grid fault.
It works in tandem with the load-shedding functionality to ensure a stable customer network after a grid event.
Islanding is handled by the Relion protection relay (REX640 or RE_615 or RE_620 series). Interface with the load-shedding solution is based on the GOOSE profile of the IEC 61850 standard for communication networks and systems for power automation for optimum results.
Detecting the following conditions and opening the utility grid circuit breaker
- Under or overvoltage
- Over or under frequency
- Rapid fall of frequency (df/dt)
- Reverse power flow (reactive power)
- Ensures that the healthy customer network stays unaffected
- Prevents cascade tripping of local generation
- Local generation continues to service process loads