Harmonic Mitigation Schemes for Wind Power Plants by Embedding Control in Wind Turbines

Abstract: Harmonic pollution may damage the electric devices in wind power plants (WPPs), and propagate to the external grid. This paper proposes a harmonic mitigation scheme by embedding harmonic control functions in wind turbines (WTs) to manage the harmonics in WPPs. It can improve the power quality at the remote Point of Common Coupling (PCC), regulated by grid codes. The proposed scheme detects the harmonics at WT buses and PCC based on instantaneous measurements, and calculates the required compensation currents. Both the general compensation scheme for reducing total harmonic distortion at the local WT buses and the specific compensation scheme for reducing the selected-order harmonics at the remote PCC are combined in the proposed harmonic mitigation scheme. Besides, a phase correction algorithm using the frequency-dependent model is proposed to compensate the phase differences between local WT buses and remote PCC. A model of offshore WPP using manufacture's field-measurement data is implemented in DIgSILENT/PowerFactory to validate the effectiveness of the proposed harmonic mitigation scheme.