虎石台220 60KV降压变电所电气部分初步设计 计算书.doc

第一章 短路电流的计算 1.1系统计算电路图和等值电路图 取SB = 100MVA，VB = Up，求得等值电路图中各阻抗标幺值如下： 发电机1:X2 = X4 = Ud%/100×SB/S = 12.4/100×100/200/0.85 = 0.0527 变压器1:X3 = X5 = Xd%/100×SB/S = 14/100×100/240 = 0.0583 发电机2:X6 = X8 = X10= Ud%/100×SB/S = 18/100×100/125/0.85 = 0.1224 变压器:X7 = X9 = X11 = Xd%/100×SB/S = 10.5/100100/160 = 0.0656 线路：2×100KM: X’= 1/2×100×0.4×100/2202 = 0.0413 60KM: X”= 60×0.4×100/2202 = 0.0496 X1 = X + X = 0.0413 + 0.0496 = 0.0909 48KM线路: X12 = 48×0.4×100/2202 = 0.0397 2×60KM线路: X13 = 1/2×60×0.4×100/2202 = 0.0248 2×100KM线路: X14 = 160×0.4×100/2202 = 0.0413 80KM线路: X15 = 80×0.4×100/2202 = 0.0661 220KV母线上K1点发生短路时的短路计算 首先进行网络化简，化简后的网络图见图: X‘1 = X* + X1 = 0.05 + 0.0909 = 0.1409 X‘2 =（X2 + X3）/2 =（0.0527 + 0.0583）= 0.0555 X‘3 = (X6 + X7)/3 =（0.1224 + 0.0656）/3 = 0.0627 X‘4 = X12 = 0.0397 X‘5 = X13 = 0.0248 X‘6 = X15 = 0.0661 X‘7 = X14 = 0.0413 进一步化简如下： 对X’5 X’6 X’7 进行三角变换 网络见图1-4所示 X”1 = X’5X’7/(X’5 + X’6 + X’7) = 0.0248×0.0413/(0.0248 + 0.0661 + 0.0413) = 0.00748 X”2 = X’6X’7/(X’5 + X’6 + X’7) = 0.0661×0.0413/(0.0248 + 0.0661 + 0.0413) = 0.02066 X”3 = X’5X’6/(X’5 + X’6 + X’7) = 0.0248×0.0661/(0.0248 + 0.0661 + 0.0413) = 0.01240 网络见图1-5所示 X ‘= X1X2/X1 +X2 = 0.1409×0.0555/（0.1409 + 0.0555）= 0.03983 X“ = （X‘ + X3）X4/（X‘ + X3 + X4） =（0.03983 + 0.04742）×0.07507/（0.03983 + 0.04742 + 0.07507） = 0.04035 X# = X ‘+ X” = 0.02066 + 0.04035 = 0.06101 C3 = X”/(X’ + X3) = 0.04035/（0.03983 + 0.04742）= 0.46250 C4 = 1 - C3 = 1 - 0.4625 = 0.5375 C1 = C3 X’/X1 = 0.4625×0.02066/0.14091 = 0.13072 C2 = C3 - C1 = 0.4625 - 0.13072 = 0.33178 X∈ = 0.06101 X1∈ = X∈/C1 = 0.06101/0.13072 = 0.46674 X2∈ = X∈/C2 = 0.06101/0.33178 = 0.18389 X4∈ = X∈/C4 = 0.06101/0.5375 = 0.11351 Xjs1 = X1∈SG1/SB = 0.46674×11000/100 = 51.3409 Xjs2 = X2∈SG2/SB = 0.18389×200/0.85/100 = 0.43268 Xjs4 = X4∈SG3/SB = 0.11351×125/0.85/100 = 0.16692 X‘∈ = X∈ + 1/2×（Ud%/100)×(100/S变X‘1∈ = X‘∈/C1 = 0.06107/0.13072 = 0.46719 X‘2∈ = X‘∈/C2 = 0.06107/0.33178 = 0.18407 X‘4∈ = X‘∈/C4 = 0.06107/0.5375 = 0.11362