A magnitude-phase detection method for grid-connected voltage of wind power generation system

In order to keep low-voltage ride-through under the grid faults for wind power generation system, the magnitude and phase information of the system grid-connected voltage must be detected fleetly and precisely so that the control subsystem of wind power generation system can tackle the faults. The conventional three-phase software phase-locked loop (SPLL) has a low speed of dynamic response because of the effects of negative-sequence and harmonic components. Also it can not exactly extract the fundamental positive-sequence magnitude and phase of three-phase voltage. This paper proposes a novel three-phase magnitude-phase detection method based on PQR transformation. The proposed method can decouple the fundamental positive-sequence component and negative-sequence component of three-phase voltage, and detect the magnitudes and phases of them respectively. The simulation results verify that the proposed method can overcome the shortcomings of conventional three-phase SPLL, track the magnitude and phase information of the fundamental positive-sequence voltage accurately and improve the speed of dynamic response effectively under the bad harmonic condition. The novel magnitude-phase detection method can be used to detect exactly the grid-connected voltage of wind power generation system.