在机组故障期间转子Crowbar投入不能为电网提供无功支持同时会从电网吸收一定无功从而导致电网运行情况进一步恶化，针对Crowbar保护的弊端提出一种低电压穿越方法，利用DC-Chopper代替Crowbar，同时在故障情况下通过对转子侧变流器进行解耦控制，控制定子侧给电网提供一定无功支持，能更好的实现机组故障穿越。基于此策略在PSCAD平台上搭建了的双馈风电场仿真模型，对比验证了风电场具有低电压穿越能力及控制策略的优越性。在此基础上，分别仿真分析不同故障类型下双馈风电场的故障特性。研究结果表明传统转子Crowbar电路的投入是机组故障电流频率为非工频的原因，而采用其他非转子Crowbar电路的机组故障电流频率为工频；风电场联络线发生任何类型的不对称接地故障，风电场侧都会表现出弱电源特性，单相接地故障表现出的弱电源特性更为明显。这对故障选相元件将会受到严重影响。研究成果具有一定的实际价值和意义。%The doubly-fed induction generator (DFIG) can't provide reactive power instead of absorbing it from the system for excitation which can bring about further deterioration. Aiming at the disadvantages of Crowbar protection presents a low voltage ride through the method, using DC-Chopper instead of Crowbar, at the same time, in case of failure by the decoupling control of rotor side converter, grid side control of stator to provide reactive power support, can better realize the unit fault crossing. Doubly fed inductiongenerator wind farm simulation model built in this strategy based on the PSCAD platform, verify the wind farm has the superiority of low voltage ride through capability and control strategy. On this basis, respectively, simulation analysis of fault characteristics of DFIG wind farm under different fault types. The results show that the traditional rotor Crowbar circuit input is fault current frequency for reasons of non power frequency, and the use of other non fault current frequency rotor Crowbar circuit for frequency; wind farm tie line of any type of asymmetric grounding fault, the wind farm side will show a weak source feature, single phase grounding fault performance a weak source feature is more obvious. The fault phase selection components will be seriously affected. Research findings has a certain practical value and significance of the research.
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