改进Crowbar电路的双馈电机三相短路参数整定

Setting of Three-Phase Short-Circuit Parameter of DFIG Based on Improved Crowbar Circuit

双馈电机在电网故障下为了保护励磁变频器,提高电网故障的控制能力,通常采用转子侧Crowbar电路。而转子侧Crowbar电路在电网跌落故障下不能向电网提供无功支撑,无法实现低电压穿越。提出了一种改进的Crowbar电路,通过控制开关将Crowbar串接到定子电路中,实现了现有Crowbar电路对DFIG的保护要求,又能够在电压跌落故障下实现低电压穿越。建立了DFIG数学模型,在对DFIG三相短路进行分析的基础上对改进的Crowbar电感数值进行参数整定。最后通过3 MW的DFIG仿真结果验证了理论分析的正确性。

Under the grid fault of doubly-ted generator in order to protect the excitation frequency converter and improve the control ability of power grid failure ,the rotor side Crowbar circuit is normally used, but rotor side Crowbar circuit under the fault fall cannot provide reactive power supporting to the grid, unable to realize low voltage across. An improved Crowbar circuit was put forward, through the control switch making Crowbar concatenate to the stator circuit, it realized protection requirements of the existing Crowbar circuit for doubly-fed wind power generator and low voltage across under voltage drop failure. A mathematical model of doubly-fed wind power generator was established. The Crowbar inductance value was set based on the analysis of three-phase short-circuit of DFIG. Finally, 3 MW doubly-fed wind turbine simulation results verify the validity of the theoretical analysis.