钟诚,魏来,严干贵
With the increase of installed capacity of wind farm, the operation stability of wind power system during grid disturbances becomes important. Grid codes require that wind power system stays connected to the grid during voltage dips for a certain period, with the ability of low-voltage ride-through (LVRT). For permanent magnet synchronous generator (PMSG), the key to improve the ability of LVRT is that fast control DC-Link voltage when grid-voltage dips. This paper proposes a LVRT control strategy for PMSG unit based on control mode switch. The strategy changes the control mode between in normal and fault of grid-voltage, and adopts the grid-side converter or generator-side converter to control the DC-Link voltage respectively. In addition, this paper proposes an improved feed-forward method to speed up the DC bus control, which can accelerate the speed control and reduce the peak value of the DC bus voltage. The simulation results validate the effectiveness of the proposed strategy.