Application of over-current relay in offshore wind power plant grid with VSC-HVDC connection

This paper presents the setting and coordination of over-current relays in an offshore wind power plant (WPP) grid connected only to the power electronic converters with limited fault current capability. The limited fault current injection capability of the converters has been considered as a hindrance for the relay setting. This characteristic can be utilized to develop a deterministic picture of the radial grid network and then the relays settings could be applied. The relay coordination has been demonstrated through an implementation in the Real Time Digital Simulator (RTDS) platform. The setting of relay parameters based upon maximum nominal currents is explained and the consequences are investigated.