Export Cable Protection for Offshore Wind Farms Using Type-IV Wind Turbine Generators

Export cable protection for offshore wind farms (OWF) using Type-IV wind turbine generators (WTGs) is challenging due to the WTG's limited, variable, and unconventional fault-current response. Typically, line-current-differential relaying is used for primary protection and then, when communication is lost, the differential relays are backed up by distance relays. However, in presence of WTGs, distance protection is highly prone to misoperation. Therefore, this paper proposes a protection scheme that uses a loss-of-potential overcurrent logic for OWF export cables as an alternative backup protection. For this study, an experimental setup was created using a real-time digital simulator and physical relays to evaluate the performance of the proposed protection scheme using hardware-in-the-loop testing. Test results showed that the proposed scheme operated correctly under different types of faults and fault locations.