某110kv變電站短路電流計(jì)算書

某110kv變電站短路電流計(jì)算書一、短路電流計(jì)算取基準(zhǔn)容量Sj=100MVA，略去“*”，Uj=115KV，Ij=0.502A富興變：地區(qū)電網(wǎng)電抗X1=Sj/Sdx=Ij/Idx=0.502/15.94=0.0315km線路電抗X2=X*L*(Sj/Up2)=0.4*5*(100/1152)=0.015發(fā)電機(jī)電抗X3=(Xd’’%/100)*(Sj/Seb)=(24.6/100)*(100/48)=0.51216km線路電抗X4=X*L*(Sj/Up=0.4*16*(100/1152)=0.0495.6km線路電抗X5=X*L*(Sj/Up2=0.4*5.6*(100/1152)=0.01731.5MVA變壓器電抗X6=X7=(Ud%/100)*(Sj/Seb)=(10.5/100)*(100/31.5)=0.33350MVA變壓器電抗X=(Ud%/100)*(Sj/Seb)=0.272X8=X3+X4+X5=0.578X9=X1+X2=0.046X10=(X8*X9)/(X8+X9)X11=X10+X6=0.046地區(qū)電網(wǎng)支路的分布系數(shù)C1=X10/X9=0.935發(fā)電機(jī)支路的分布系數(shù)C2=X10/X8=0.074則X13=X11/C1=0.376/0.935=0.402X14=X11/C2=0.376/0.074=5.081、求d1’點(diǎn)的短路電流求富興變供給d1’點(diǎn)(即d1點(diǎn))的短路電流Ix″=Ij/(X1+X2)=0.502/(0.031+0.015)=10.913kASx″=Sj/(X1+X2)=100/(0.031+0.015)≈2173.913MVAichx1=√2*Kch*Ix″=√2*1.8*10.913=27.776kAIch=Ix″√1+2(Kch-1)2=10.913*√1+2(1.8-1)2=10.913*1.51=16.479kA1.2求沙縣城關(guān)水電站供給d1’點(diǎn)的短路電流將發(fā)電機(jī)支路的等值電抗換算到以發(fā)電機(jī)容量為基準(zhǔn)容量時(shí)的標(biāo)幺值Xjs=X8*Srg/Sj=0.578*48/100=0.277查表得I*’’=3.993I*0.2=3.096I*4=3.043換算到115kV下發(fā)電機(jī)的額定電流:Ief=Srg/(3Up)=48/(1.732x115)=0.241求得:If’’=I*’’*Ief=3.993x0.241=0.962kAIf0.2’’=I*0.2’’*IIf0.4’’=I*4’’*Iichf=√2*Kch*If″=√2*1.8*0.962=2.448kA1.3求得d1’點(diǎn)的短路電流Ix″=10.913+0.962=11.875kAich=27.776+2.448=30.224kAIch=11.875√1+2*(1.8-1)2=17.93kA2、求d2點(diǎn)的短路電流Ix″=Ij/(X1+X2+X6)=5.50/(0.031+0.015+0.333)=14.512kAichx=2*Kch*Ix2″=2*1.8*14.512=36.936kAIch=Ix″√1+2(Kch-1)2=14.512*√1+2(1.8-1)2=21.913kA3、求d2’3.1求富興變供給d2’點(diǎn)的短路電流Ix″=Ij/X13=5.5/0.402=13.68kAichx1=√2*Kch*Ix″=√2*1.8*13.68=34.82kAIch=Ix″√1+2(Kch-1)2=13.68*√1+2(1.8-1)2則Rt=1/(100*0.58/126.5+0.25/1.24)≈1.5Ω六、現(xiàn)有避雷針保護(hù)范圍計(jì)算現(xiàn)下洋變有四支等高避雷針（相對站內(nèi)地面標(biāo)高），位置詳見B992C-D0101-03。令hx=10m，則rx=(1.5h-2hx)p=(1.5x30-2x10)=25h0AB=h-D/7p=30-60/7=21.43m則A、B兩針間高度為hx=10m水平面上保護(hù)范圍的一側(cè)bxAB=1.5h0-2hx=1.5*21.43-2*10=12.1同理h0BC=h-D/7=30-50/7=22.85m則bXBC=1.5