基于Crowbar的双馈风力发电低电压穿越研究

随着风力发电机容量和风电规模的增加,要求双馈感应发电机(DFIG)能够实现低电压穿越(LVRT)能力。在电网电压跌落的对称故障下,针对原有LVRT技术的不足,提出一种采用主动式Crowbar电路的控制策略。在电压跌落后,转子电流突升时,触发Crowbar电路,旁路转子侧变换器;在电流恢复到一定程度时,断开Crowbar电路,使转子侧变换器投入工作。通过有、无Crowbar电路仿真对比表明,该方法可较好地控制转子过电流、母线过电压及电磁转矩的振荡,同时在故障期间向系统输送无功,达到LVRT的要求。

Doubly-fed Induction Generator Low Voltage Ride Through Based on Crowbar Circuit

With the development of wind power generator capacity and wind power system,it is required that doubly-fed induction generator(DFIG) has the ability of low voltage ride through(LVRT).At the symmetric fault of voltage dip,considering the disadvantages of existing LVRT technologies,an active Crowbar control strategy is proposed.After the voltage dip,the rotor current increases sharply,triggering the Crowbar circuit,short circuit the rotor side converter(RSC).When the current recovers to some value,cut off the Crowbar,to shift the RSC into normal work.The compar-ison of simulation results with Crowbar and without it shows,this method can do a better control of rotor overcurrent,bus overvoltage and torque oscillation;it can also provide passive power to grid during the fault.So this method satis-fies the requirements of LVRT.