直驱风力发电机组全功率变流器网侧甩负荷故障分析及保护策略研究

Research on the Analysis and Protective Strategy of Grid side Load Throw-off Fault of Full Power Converter for Direct-drive Wind Turbine

直驱技术在目前大容量风力发电机组的比例越来越高,而全功率变流器在直驱机组中起到了连接电网与发电机的惟一能量转换通道作用,其可靠性对整机的可利用率有决定性意义。本文对直驱机组正常运行情况下,因箱变低压侧或高压侧突然跳闸导致变流器网侧甩负荷的故障工况进行了详细分析。通过分析可以看出,这种工况下如果没有采取有效保护,会导致变流器直流母线电压骤升,会导致功率器件失效,特别是IGBT模块。因此本文提出来一种保护策略并通过仿真验证该策略的有效性。

Direct-drive technology is applied in large scale wind turbine more and more popularly. As only power pathway between the grid and the Direct-drive wind turbine, the reliability of full power converter is very important for utilization ratio of turbine. In this paper, the fault of load throw-off on the grid side is analyzed in detail. Under this fault operating mode, if the effective protection is not adopted, the DC bus voltage of converter will steps up quickly, and the power devices especially IGBT modules will be broke down. Thus a novel protective strategy is proposed and the validity of the strategy is supported by simulation result.