Protection algorithm for a wind turbine generator based on positive- and negative-sequence fault components

A protection relay for a wind turbine generator (WTG) based on positive- and negative-sequence fault components is proposed in the paper. The relay uses the magnitude of the positive-sequence component in the fault current to detect a fault on a parallel WTG, connected to the same power collection feeder, or a fault on an adjacent feeder; but for these faults, the relay remains stable and inoperative. A fault on the power collection feeder or a fault on the collection bus, both of which require an instantaneous tripping response, are distinguished from an inter-tie fault or a grid fault, which require a delayed tripping, using the magnitude of the positive-sequence component in the fault current. The fault type is first evaluated using the relationships between the positive- and negative-sequence fault components depending on type of fault. Then the magnitude of the positive-sequence component in the fault current is used to decide on either instantaneous or delayed operation. The operating performance of the relay is then verified using various fault scenarios modelled using EMTP-RV. The scenarios involve changes in the position and type of fault, and the faulted phases. Results confirm that the relay can successfully distinguish between faults that require an instantaneous, delayed or non-operation response.