感应电动机负荷对短路电流影响机理研究

通过理论推导,提出了感应电动机定子侧发生三相短路后反馈短路电流的解析表达式.通过分析,掌握了感应电动负荷反馈短路电流特性,指出电动机反馈短路电流衰减速度随容量增大而减慢;考虑磁路饱和特性导致反馈短路电流增大;并非所有电动机均反馈短路电流.通过电磁暂态仿真手段,详细分析了在不同负荷类型条件下,感应电动机负荷对输电网短路电流水平的影响.得出电力系统中,接入6/10 kV 电压等级的电动机对220 kV 以上输电网的短路电流水平影响较大,建议计算中考虑其影响.

Impact of Load Induction Motoron Power System Short-Circuit Current Calculation

The analytic expression of feedback current of short-circuit current of induction motor under the condition that three-phase short-circuit fault occurred in its stator is theoretically derived.The characteristic of feedback current of the short-circuit current of induction motor load is analyzed and it is pointed out that the attenuation of the feedback short-circuit current decelerates along with the increase of induction motor capacity.The saturation characteristic of magnetic circuit makes the feedback current increased,and it is really not for all induction motors to feed short-circuit current back.By means of electromagnetic simulation,the impacts of induction motor load on short-circuit current level under various types of loads are analyzed in detail,and the conclusion that the induction motors connected to 6kV and 10kV power network greatly influence the short-circuit current level of 220kV power network is obtained,therefore it is recommended that in the calculation of short-circuit current levels of 220kV and above power grids such an influence should be taken into account.