图3-2网络简化图
X11?X1//X2?4.856?2.4282
X12?X9?X10?0.91716?0.393?1.310
X13?X7?X3//X4?1.4?4.856?3.828 2X14?X8?X5?2.8?4.856?7.656 继续简化上图:
图3-3网络简化图
X15?X13//X14?3.828?7.656?2.552
3.828?7.656再化简得:
图3-4网络简化图
X16?X12?X6?X12X6?3.429 X15
X17?X15?X6?X15X6?9.710 X12三相短路电流周期分量计算: 系统A侧:
IZA?''Sd?Ij(10.5)X16SjX16??54.986?16.036kA3.4291000?291.630MVA3.429
B侧()的计算电抗为Xjs?X17Sn142.104?9.710??1.371 Sj1000由计算电抗查水轮机短路电流运算曲线得:
10.5kV侧额定电流为:
Sn(F3~F5)142.104In(F3~F5)??7.814kA
3Uj3?10.5''''因此:IZ?I*kA ZIn(F3~F5)?0.752?7.814?5.876 IZ0.2?I*Z0.2IN(F3~F5)?0.731?7.814?5.712kA IZ2?I*Z2In(F3~F5)?0.834?7.814?6.517kA
IZ4?I*Z4?In(F3~F5)?0.837?7.814?6.540kA Sd?I*ZSn(F3~F5)?0.752?142 .104?106.862MVA''''C侧()的计算电抗为: Xjs?X11Sn94.736?2.428??0.230 Sj1000由计算电抗查短路电流运算曲线得:
其10.5kV侧的额定电流为:
Sn(F1~F2)94.736In(F1~F2)???5.209kA
3Uj3?10.5因此:
'' IZ?5.087?5.209?26.498kA IZ0.2?3.523?5.209?18.351kA
IZ2?3.238?5.209?16.867kA IZ4?3.328?5.209?17.336kA
''''Sd?I*.922MVA ZSn(F1~F2)?5.087?94.736?481所以,点的三相短路电流为:
'' IZ?16.036?5.876?26.498?48.410kA
IZ0.2?16.036?5.712?18.351?40.099kA
IZ2?16.036?6.517?16.867?39.420kA IZ4?16.036?6.540?17.336?39.912kA
''Sd?291.630?106.862?481.922?880.414kA
点三相短路冲击电流及全电流最大有效值计算:
(1).系统A侧和三电源B侧的值采用远离发电机地点发生短路时的数值,则=1.80,=0.97 =
=1.80
(16.036+5.876)=55.779KA
=
(16.036+5.876)
0.972?2?(1.80?0.97)2?33.366
(2)C侧二电源的,值采用发电机机端短路时的值,故=1.90,=0.93 ==1.9026.498=71.200KA
26.4980.932?2?(1.90?0.93)2?35.608kA (3) 总的冲击电流及全电流为: =55.779+71.200=126.979KA =33.3666+35.608=68.974KA 点短路电流热效应计算: = 其中t取4S
48.4102?10?39.4202?39.9122?4 =
12=6491.953k 点短路电流计算.
网络简化如下,并结合其正序阻抗图得,

