华北电力大学科技学院电力系统故障分析课 程设计。计算5节点电路图中各节点正负零序电压，以及ABC三相相电压，还有9条支路的正负零序电流，以及ABC三相相电流。-Course design of power system fault analysis in College of science and technology of North China Electric Power University. Calculate the positive and negative zero seque