43.15 21.33 0 64.48 110 90 20 15 235
-120
4
补偿后低压 负荷
389.11 177.59 427.72
短路电流计算: 二) 短路电流计算:
短路等效电路图:
(1)
基准定量
Sd =100MVA
基准电压
Ud (1) =10.5kv Ud2=0.4kv
Id (1) = Sd /
3 * Ud (1) =100/ 3 *10.5=5.5KA
Id (2) = Sd / 3 * Ud (2) =100/ 3 *0.4=144.3KA
(2)
取基准定量
Sd =100MVA
基准电压
Ud (1) =10.5kv Ud (2) =0.4kv
Id (1) = Sd /
3 * Ud (1) =100/ 3 *10.5=5.5KA
Id (2) = Sd / 3 * Ud (2) =100/ 3 *0.4=144.3KA
(3)各元件电抗标幺值: 电力系统: X * (1) = Sd / Soc =100/500=0.2
线路
WL(1): X
* (2) = Xw1 * Sd / ud =0.4*1*100/10.5*10.5=0.36
2
线路
WL(2): X * (3) = Xw1 * Sd / ud =0.08*0.5*100/10.5*10.5=0.036
2
变压器
X*(φ)=
uk /100*100%* Sd / Sn =(4/100)*(100/0.5)=8
(4)
求
Kn 点的总电抗标幺值及电抗之和
X *∑ (1) = X * (1) + X * (2) + X * (3) =0.2+0.36+0.036=0.596
5
IK (1) = Id (1) / X *∑ (1) =5.5/0.596=9.23KA
ISH =2.55* IK (1) =2.55*9.23KA=23.54KA ISH =1.51* IK (1)
=1.51*9.23KA=13.94KA SK = Sd / X *∑ (1) =100/0.596=167.79MVA
X *∑ (2) = X * (1) + X * (2) + X * (3) + X * 4 =0.2+0.36+0.036+8=8.596
Ik (2) = Id (2) /
X *∑ (2) =144.3/8.596=16.79
ish =1.84*Ik(2)=1.84*16.79=30.89
ISH =1.09*Ik(2)=1.09*16.79=18.3 SK (2) = Sd / X *∑ (2) =100/8.596=11.63
计算结果见下图
短路计算 短路电流
/KA 短路容量/MVA
Ish (3) Ish (3)
I
K-1 K-2
(3) K
I
''(3)
I
(3) ∞
S
(3)