电网故障下双馈风力发电机组的控制策略研究

Research on Aontrol Strategies of Double-fed Wind Power Generator Set Under Grid Faults

双馈风力发电机(DFIG)系统变流器仅对发电机的转差功率进行变换,因此它比同容量直驱风力发电机的变流器容量小很多,但这使得它对电网故障的抵御能力较弱.本文针对双馈风力发电系统在电网故障下的控制策略进行研究.在电网故障时,DFIG系统的控制包括阻止风轮过速进行的桨距角控制和功率变流器在电网故障期间和之后的保护和电网电压支持控制.为了在电网故障期间提高DFIG电网电压支持能力,在正常运行时的DFIG控制结构基础上加入了另一控制级.这个控制级包括阻尼控制器、转子侧变流器、电压控制器和网侧变流器无功补偿器.仿真结果证明了所提出方案的可行性.

The converter of doubly-fed wind power generation system only converts the slip power of the generator,so its capacity is much smaller than that of the direct-drive wind turbine with the same capacity,which makes it weak to resist the power grid failure.In this paper,the control strategy of doubly-fed wind power generation system under grid fault is studied.In the case of grid failure,the control of DFIG control system includes pitch angle control to prevent wind turbine overspeed,power converter protection and grid voltage support control during and after grid failure.In order to improve the voltage support capability of the DFIG grid during grid failure,another control stage is added on the basis of the DFIG control structure during normal operation.This control stage includes a damping controller,a rotor-side converter voltage controller and a grid-side converter reactive compensator.Simulation results demonstrate the feasibility of the proposed method.