由于三序网络节点导纳阵完全相同，因此正负零序的端口阻抗矩阵也相同 Z11=3*j0.05=j0.15， Z12?(11??1)?(?j0.05)?0 2??同理：Z22=3*j0.4=j1.2, Z12?(?1?1?1)?(?j0.05)?0, 所以： ?2?j0.15?0?
0??I?j1.2????I'1(1)'2(1)??1??I?0?????2?????0.95???I'1(1)'2(1)1?1???''jj??0.15??I1(2)??I1(0)??0.15???????'???2???'2?0.95?0.95?II?????????j?2(2)??2(0)??j???1.2???1.2??1??j?I1(0)??0.15??I???0.95?2??2(0)??j???1.2??1??'??jI1(1)?I1(2)??0.15?????1?I??0.95??'I2(1)??2(2)???????j?1.2??1??10.05*0.95??U1(1)??1???0.05?0.05??j0.15??1?3?1.2??j????????0.050.4??0.95??10.95U0.95??????j?2(1)????0.95???33??1.2??1??10.05*0.95???j?U1(2)???0.05?0.05??0.15???3?1.2???j????0.95????10.95?U?0.050.4????2(2)???j????33?1.2???1??10.05*0.95?2??j??U1(0)??0.05?0.05??0.15???3?1.2????j?2??0.95?2???10.95?U?0.050.4????j????2(0)???????1.2???33?（2）求故障口各相电流分量。
?1?'??I1(1)?I1(1)??j0.15??I???1I'???0.95?2(1)?2?2(1)???????j?1.2?
?I1a??1?I????2?1b??????I1c????I2a??1?I????2?2b??????I2c???1??21??21??I1(1)??j20?????1?I?01(2)???????0?1?????I1(0)??1??I2(1)??0????2?1?I?j2.375?2(2)????????1?0????I2(0)??
?U1a??1?U????2?1b??????U1c????U2a??U???2b???U2c???1??2????1??21??21??U1(1)??0????2?1?U?1.19???1(2)?????1???U1(0)??????1??U2(1)???1?U??2(2)???1????U2(0)??1.95??0?????0.95???
注：本题给的参数有些问题，导致求出的电压是不合实际的。
可把阻抗矩阵的主对角元0.05改为0.5后，结果会合理。
21、 某电力系统在节点2发生B相单相接地短路故障，同时在节点7发生B、
C两相接地短路。试画出该系统故障时的复合序网图，并确定相应理想变压器的变比。
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