中文摘要：

双馈风机DFIG（doubly-fedinductiongenerator）的低电压穿越能力LVRT（lowvoltageridethrough）正逐渐成为大型风电场必备的功能之一。为了使带有Crowbar保护电路的DFIG在电网故障阶段发出一定的无功支持电网电压的恢复，充分利用变频器的无功产生能力，在电压跌落期间，给定网侧变频器一无功指令值，并使用无功电流优先的原则进行控制。为了减少投资，增强DFIG的无功发出能力，把机侧和网侧变频器并联向系统发无功，并增大直流侧电容来增强系统的稳定性。仿真结果表明，网侧和机侧变频器都可以对电网进行无功支撑，提升了机端电压，增强了双馈风机的低电压穿越能力。

英文摘要：

Low voltage ride through（LVRT）capability is becomig an essential function for the gird-connected DFIG. In order to make the DFIG with crowbar circuit product some reactive power during the period of grid fault to make grid voltage recover,author makes full use of grid-on converter＇s reactive power producing ability, a reactive power command to grid-on converter is given,which is controlled by the strategy of priority of reac tive current. In order to reduce investment, the operation of parallel cinverter is to enhance the ability of reactive power producing,and the capacitance of DC side is increased to enhance the stability of system. Simulation re- suits prove that the reactive power of grid can be supported by the two converters,which improve the grid volt- age and enhance the LVRT capability of DFIG.