2×100MW发电厂电气部分设计毕业设计

X27?X24?XL5?X24?XL5?0.667 XSXL5?XS?0.454 X24X28?XL5?XS?

X25?0.155?0.27?0.098

0.155?0.27X26?X25?X4?0.098?0.108?0.206

用分布系数法计算转移电抗 从图知I4?If 即C???I4?1 If0.27?0.635

0.27?0.155得C1?C2?1?0.635?0.365

C3?X230.377?0.635?0.449 ?C1?0.377?0.156X23?X19C4?C1?C3?0.635?0.449?0.186 C5?X280.454?0.365?0.148 ?C2?0.454?0.667X27?X28C6?C2?C5?0.365?0.148?0.217

转移电抗 XG1f?X260.206??0.459 C30.449 25

XG2f?X2?0.156

XG3.4f?X260.206??0.108 C40.186X260.206??1.392 C50.148XG5.6f?XSf?X260.206??0.949 C60.217计算电抗 XjsG1?XG1fS?N?0.459?SB1000.85?0.54 1001000.85?0.184 10050?20.8?1.385 100?20.8?1.74 100 XjsG2?XG2fS?N?0.156?SBXjsG3.4?XG3.4fS?N?1.108?SBS?N?1.392?SB50XjsG5.6?XG5.6fXjs?s?Xs?f?SN500?4.745 ?0.949?100SB查运算曲线得电流周期分量标幺值 因为 Xjs?s?4.745?3.45 则按 IPS??11??0.211 Xjs?s4.745t?0s时

IG0??1.87 IG0??5.82 IG12?3.40?0.76 IG?5.60?0.52 IS0??0.36 ?0.59 IS0.2??5.2

t?0.2s时

IG0.2??1.68 IG0.2??3.93 IG12?3.40.2?0.69 IG5.60.2?t?4s时

IG4??1.97 IG124??2.43 IG?3.44?0.76 IG5.64??0.61 IS4??2.41

I 有名值

26

If0?IG10?IG20?IG3.40?IG5.60?IS0

?IG0??1SG13U0.V?SG5.6?IG0??2SG23U0.V?S?IG

?3.40?SG3.43U0.V?

IG

5.60?3U0.V?IGS0?3U0.V10010050?250?25000.850.850.8?1.87??5.82??0.76??0.52?0.8?3.6?3?1153?1153?1153?1153?115?4.542?0.803?9.037

?14.382

If0.2?3.314?0.803?13.054?17.171

4.7 短路电流冲击值及全电流最大有效值计算

ich?2kchI?? （4-9）

式中 ich---短路电流冲击值 Kch---短路电流冲击系数

对于冲击系数Kch，如果电路只有电抗，则;如果电路只有电阻，则；Ta?0,Kch?1所以可知2??Kch??1。工程设计中，我国对Kch推荐值如下表：

表4-4 我国推荐的冲击系数Kch

短路地点 发电机端 发电帮高压侧母线 远离发电厂的地点 Kch ich?KA? //2.69I //2.63I //2.55I 2Ich?KA? //1.62I //1.56I //1.51I 1.9 1.85 1.8 Ich?I??1?2?Kch?1? （4-10）

式中 Ich---全电流最大有效值 短路电流数据列表

27

28