Design and Evaluation of a Protection Relay for a Wind Generator Based on the Positive- and Negative-Sequence Fault Components

To avoid undesirable disconnection of healthy wind generators (WGs) or a wind power plant, a WG protection relay should discriminate among faults, so that it can operate instantaneously for WG, connected feeder or connection bus faults, it can operate after a delay for inter-tie or grid faults, and it can avoid operating for parallel WG or adjacent feeder faults.

A WG protection relay based on the positive- and negativesequence fault components is proposed in the paper. At stage 1, the proposed relay uses the magnitude of the positive-sequence component in the fault current to distinguish faults at a parallel WG connected to the same feeder or at an adjacent feeder, from other faults at a connected feeder, an inter-tie, or a grid.

At stage 2, the fault type is first determined using the relationships between the positive- and negative-sequence fault components. Then, the relay differentiates between instantaneous operation and delayed operation based on the magnitude of the positivesequence component in the fault current. Various fault scenarios involving changes in the position and type of fault and the faulted phases are used to verify the operating performance of the relay with EMTP-RV generated data.

Results indicate that the relay can successfully distinguish the need for instantaneous, delayed, or non-operation.