2×100MW发电厂电气部分设计毕业设计 下载本文

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