2.2．三相短路
1． 35KV系统三相短路电流计算
220KV35KVX8X2X73D1X1
<图三>
21X2X8<图四>
X9?X7?X1?0.0084?0.028?0.0364 <图五>
XXD1
X?1?X9?X8?X9?X80.0364?0.017?0.0364?0.017??0.16 X20.5X?2?X2?X8?X2?X80.5?0.017?0.5?0.017??14.72 X90.0364计算电抗
Xijs1?XSN118000?0.16??28.8
?1SB100SN2100?14.72??14.72
?2SB100Xijs2?X查曲线求得 1I1??0.0347
28.81I2??0.07
14.72?3?IDI?0.0347?180003?37?0.07?1003?37?9.85KA
2． 220KV系统三相短路电流计算 <图六>
XXD1 <图七>
X?1?X7?X1?0.0084?0.028?0.0364
X?2?X2?0.5
计算电抗
Xijs1?XSN118000?0.0346??6.552
?1SB100
Xijs2?XSN2100?0.5??0.5
?2SB100查曲线求得
I1?0.1526
I2?2
?3?ID2?0.1526?180003?230?2?1003?230?7.4KA
3． 500KV系统三相短路电流计算 <图八>
220KV35KVX8X2X73D3X1
<图九>
21D3
XX?1?2?X1?0.028
?X7?X2?0.0084?0.5?0.5084
计算电抗
Xijs1?XSN118000?0.028??5.04
?1SB100
Xijs2?XSN2100?0.5084??0.5084
?2SB100查曲线求得 1I1??0.198
5.04I2?1.9
?3?ID3?0.198?180003?525?1.9?1003?525?4.139KA
2.3单相短路计算
2.3.1 35KV系统单相短路电流计算 I\?0
由于主变压器为自耦变压器其35KV侧为三角形接线,而零序电压施加在各种类型变压器绕组的三角形(d形)侧或不接地星形(Y形)侧时,无论其他侧绕组接线方式如何,变压器中都没有零序电流流通,此时变压器的零序电抗X0??所以35KV系统单相短路电流为零
2.3.2 220KV系统单相短路电流计算 正序网 <图十>
X1X7X▲X2 负序网 <图十一>
X2X1X7 零序网 <图十二>
X2X1X7X8X.5??0.028?0.0084??2?X2//?X1?X7??00.5?0.028?0.0084?0.03X?0?X2//?X1?X7?//X8?0.005
X??X?2?X?0?0.03?0.005?0.035
XX?G1f??X1?X7????111???X??1?X7X2X????0.0364?0.035???111?
?0.0364?0.035?0.5???0.073X???111?G2f?X2X???X1?X?7X?2X????0.5?0.035???111?
?0.0364?0.035?0.5???1.016计算电抗
Xijs1?XSN1G1fS?0.073?18000?13.14 B100XSN2ijs2?XG2fS?1.016?100100?1.016 B查曲线求得 I?1113.14?0.076
I2?0.98
I?1?D4?0.076?180001003?230?0.98?3?230?3.64KA
I\?3I?1?D4?3?3.63?10.92KA