A Virtual Filter Approach for Wind Energy Conversion Systems for Mitigating Power System Frequency Fluctuations

The increasing penetration of wind power may deteriorate power system frequency performance. This paper proposes a novel virtual filter (VF) approach for a grid-connected wind energy conversion system to mitigate power system frequency fluctuations. The principle is to modify the traditional wind power controller to emulate a physical energy storage system to smooth the wind power output. The VF proposed in this paper is tuned as a band-stop filter to selectively reject the power system frequency-sensitive components in wind power output. Therefore, the power system frequency fluctuations can be correspondingly reduced with only a small amount loss of wind energy. The advantages of the proposed VF are: 1) no need for a physical deployment of energy storage system, 2) no need for power system frequency signal and communication channel, and 3) ability to selectively filter the power system frequency sensitive components. Simulation results verified the outstanding performance of the proposed VF in system frequency fluctuation mitigation, while with less wind energy loss comparing with existing method.