计及低电压穿越的双馈感应发电机三相短路运算曲面法

分析了常规电源对双馈感应发电机(DFIG)的电压支撑作用,将DFIG接入点以外的系统进行戴维南等值,利用DFIG短路电流周期分量与计算电抗、开路电压的关系曲面,提出了DFIG接入电网的短路电流运算曲面法。针对撬棒投入和未投入时DFIG的暂态特性差异,以转子电流峰值为撬棒投入的判据,分析撬棒动作与故障后DFIG端电压关系;考虑转子励磁控制和撬棒动作延时,推导了DFIG三相短路电流计算式;制定不同时刻DFIG三相短路电流与计算电抗、开路电压运算曲面,给出计及低电压穿越的DFIG短路运算曲面法计算步骤,通过仿真验证该方法的正确性。

Three-phase Short Circuit Calculating Method Based on Pre-computed Surface for Doubly-fed Induction Generators Considering Low-voltage Ride Through

The voltage support from conventional energy sources to doubly-fed induction generators (DFIGs) is analyzed by making the systems outside the coupling point of DFIG Thevenin equivalent. A short circuit calculating method based on pre-computed surface is proposed by developing the surface of short circuit current varying with the calculated reactance and the open circuit voltage. Moreover, for the transient feature differences of DFIG during the crowbar activation and deactivation, the rotor current peak is used to judge the activation, the relation between crowbar activation and post-fault terminal voltage is investigated. And the short circuit currents are derived by taking into account the rotor excitation and crowbar activation time delay. Finally, the pre-computed surfaces of short circuit current at different times are established, and the procedure for DFIG short circuit calculation is designed. The correctness of proposed method is verified by simulation. This work is supported by National Natural Science Foundation of China (No. 51277184) and National High Technology Research and Development Program of China (863 Program) (No. 2011AA05A107).