应用撬棒电路的双馈型风力发电机低电压穿越分析

风电场规模已经变得越来越大，风电机组的解列会严重影响系统的稳定性，这就要求风电机组具有低电压穿越能力以应对电网电压跌落。由于DFIG的定子侧直接与电网相联，在电网电压突然跌落时，定转子中会出现很大的电压和电流，需采用Crowbar电路（撬棒电路）来旁路转子侧变流器。文中分析了Crowbar电路的控制原理，然后在理论分析的基础上进行了仿真，仿真结果验证了Crowbar电路能够帮助DFIG在故障期间实现低电压穿越，最后进一步分析了Crowbar电路投切时间的选取。

Analysis on LVRT of DFIG with Crowbar Circuit

Afer large-scaled wind turbine generators are connected in the grid,loss of these wind generators will exert serious impacts on the stability of the grid,therefore the wind turbine generators must be equipped with LVRT(low voltage ride-through) ability to respond to the possible grid faults.During the period of a grid fault,over-current and over-voltage are induced in stator and rotor windings and to protect the converter,the Crowbar circuit is used to short the DFIG rotor.This paper analyzes the control theory of the Crowbar circuit and verifies the theory analysis by simulation.The simulation results show that the Crowbar circuit helps the DFIG-based wind power generator to realize LVRT in a fault.Finally,the activated time and shut time of the Crowbar circuit is further studied.