所以取In=200 A 由表4-2查得：Ib=5.5 A
IbUN65.5?10310XK.* = XK?=1.565 (2-9) ????INUb10020010.52．分段电抗器电抗标幺值参数计算： In=200 A XK=10
查表可得：XK.*=2.62
五、 系统网络化简
（系统最大运行方式时，归算到Sb＝100MVA的等值电抗Xs＝0.5）
依据本变电站选定的接线方式及设备参数，进行网络化简如下：
图2-2
六、 110kV母线短路点K1的短路计算
网络化简如图2-3：
8
图2-3
X?*=Xs= XL*1=0.222 Xjs=Xmd
SnS?0.517?233= 0.517 b100因为Xjs=0.517〈 3 所以查表得：I\* =1.913
I\
0.2* =1.655
I?* =1.953
I1\* =1.635
Ib=
Sb3U?100= 0.502 KA b3?115In=IbSnS?0.502?233=1.170 KA b100I\=I\*In=1.913×
1.170=2.238 KA I\0.2=I\0.2* In=1.665×
1.170=1.947 KA I?=I?* In=1.953×1.170= 2.285 KA I1\=I1\* In=1.635×1.170= 1.913 KA ich=2.55I\=2.55×2.238=5.707 KA ioh=1.52I\=1.52×2.238=3.402 KA S\=3I\Un=3?2.238×110=426.384 MVA
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(2-10) (2-11) (2-12)
(2-13) (2-14) (2-15)
(2-16)
(2-17) (2-18)(2-19)
七、 35KV母线短路点K2的短路计算
图2-4 图2-5 网络化简如图2-4、2-5： X?*=X3=XS
X1?X20.44?0.02?0222?=0.432 (2-20) 22S233=1.007
Xjs=Xmdn?0.432?Sb100因为Xjs=1.007〈 3 所以查表得：I\* =0.985
\I0.2* =0.910
I?* =1.067
\I1* =1.003
Ib=
Sb3Ub?100=1.56 KA 3?37In= IbSn233=3.635 KA
?1.56?Sb1003.635=3.580 KA I\=I\*In=0.985×
\\
I03.635=3.308 KA .2=I0.2* In=0.910×
I?=I?* In=1.067×3.635=3.879 KA
\\I1=I1* In=1.003×3.635=3.646 KA
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ich=2.55I\=2.55×3.580=9.129 KA ioh=1.52I\=1.52×3.580=5.442 KA
S\=3I\Un=3?3.580×35=217.020 MVA
八、 10KV母线短路点K3的短路计算
图2-6 图2-7 网络化简如图2-6、2-7： X?*=X4=XS?
(X1?X3?XD1)(X1?X3) (2-21)
X1?X3?X3?XD1?X1?X3(0.44?0.28?2.62)(0.44?0.28) =0.222?
0.44?0.28?2.62?0.44?0.28 =0.814
S233=1.897
Xjs=Xmdn?0.814?Sb100因为Xjs=0.517〈 3 所以查表得：I\* =0.540
\I0.2* =0.511
I?* =0.550
\I1* =0.550
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Ib=
Sb3Ub?100=5.499 KA
3?10.5In= IbSn233=12.812 KA
?5.499?Sb10012.812=2.238 KA I\=I\*In=0.540×
\\
I012.812=6.547 KA .2=I0.2* In=0.511×
I?=I?* In=0.550×12.812=7.047 KA
\\I1=I112.812=7.047 KA * In=0.550×
ich=2.55I\=2.55×6.918=17.641 KA ioh=1.52I\=1.52×6.918=10.515 KA
S\=3I\Un=3?6.918×10=119.820 MVA
九、 10KV出线短路点K4的短路计算
网络化简如图2-8、2-9：
图2-8 图2-9
X?*=X4=XS?(X1?X3?XD1)(X1?X3)?XD2 (2-22)
X1?X3?X3?XD1?X1?X3 12