The medium voltage collector feeder in a wind farm is usually protected by conventional protection strategy. The main drawback of this protection can't discriminate between faults occurred in the wind turbine generator (WTG) and cable feeder faults. Moreover, the protection relay did not isolate the faulted cable feeder from the side of WTG. Therefore the fault still feeded from the WTG. A new digital protection algorithm is proposed in this thesis based on fault current direction. A set of protection zones are identified based on collection bus voltage and current signals from each wind turbine. The proposed protection algorithm identifies the fault location based on the direction of the phase angle between voltage and current signals. The algorithm discriminates between internal faults in the protected collection feeder and external faults in the power grid or any parallel feeders. The protection zones are identified where each WTG has its own zone and one zone for the collection cable feeder. The proposed protection algorithm performance is verified using various fault scenarios using MATLAB package. The simulated scenarios involved different fault types and locations. The proposed algorithm is applied on a part of Zafarana wind farm which connected to 220 kV network of the unified Egyptian network. The proposed protection algorithm is implemented through a hardware laboratory experiment. A laboratory model of induction generator, synchronous generator, auto voltage transformer, current transducers and data acquisition card are used for the experiment. LabView package is used for the data acquisition. Both simulation and experimental results verified the effectiveness of the algorithm.
Wind Farm; Collector Feeder; Induction Generator; Synchronous Generator; Hardware Laboratory Experiment; Digital Protection Algorithm; Direction Algorithm; Internal Faults and External Faults.