1短路容量的确定

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1、1短路容量的确定2整流装置主电量计算（1）电解槽参数电解槽：25kt/a,164对/台槽电压：3.08（期待值）电流密度：（运行値）5.0KA/m2（设计值）6.0KA/m2（2）最大要求电压595V电流15kAX4系统（3）空载电压Udio=Udn（1+P/Pt）+S*Ns*Utm+lUd/（1-b%）（CoSamax-Kx*Ux%）式中：P/Pt=0.01（变压器铜耗百分值）；P-变压器铜损；Pt-变压器直流功率S*Ns*Utm=2*1*1.5=3（V,）式中：S-挤臂串联数，三相桥全控S=2;Ns-每个桥臂元件串联数；Utm-元件峰值压降，取1.5V;LUd=3V附加的直流压降。CoSa

2、max=CoS20=0.94（深控后有额定电压输出），控制角a=20Kx*Ux%=0.5*10%=0.05式中：Kx-变压器的直流压降换算系数，取0.5;Ux-变压器阻抗的电抗部分。b%=5%，电网电压波动系数。空载电压Udio=595*1.01+3+3/(1-0.05)(0.94-0.05)=606.95/0.85=714V(4)空载直流功Pdo=Udio*Idn=714*15=10710kw/5)整流变压器网侧容量SI=1.05Pdo=11245.5kVA，取11250kVA(6) 110kv侧网侧电流IL=SL/辺UL=11250/1.732*110=59A对于6脉波整流装置，基波有效值

3、与整个波形的有效值比为0.955，网侧基波电流IL/1)=0.955*59=56A3各次谐波计算3.1特征谐波的次数h=k*p1式中：k整数1、2、3。P-整流电路的相数或每周脉动数，这里取p=123.2重叠角计算设Uk%=10%,a=15。(1)控制角a=0时的换相角为u0CoSu0=1-Uk%=1-10%=0.9,u0=25.8=26./2)控制角a半0时的换相角为uCoS/a+u)=CoSa-/1-CoSu0)CoS/15+u)=CoS15-1+0.9=0.86615+u=30,u=153.3网侧谐波电流有效值与基波电流有效值之比根据a=15u=15，由下式计算Ih/IL/1)=1/h(

4、CoSa-CoS/a+u)*(Sin令Kh=Ih/IL(1),计算结果如下：K5=0.186K7=0.124K11=0.063K13=0.046K17=0.022K19=0.0142K23=0.0051K25=0.004K29=0.0058K3仁0.0064K35=0.0062K37=0.0055K4仁0.0037K43=0.0028K47=0.0012K49=0.0011I5=K5*IL(1)=0.186*56=10.416(A)I7=0.124*56=6.944(A)111=0.063*56=3.528117=0.022*56=1.232123=0.0051*56=0.2856I29=0.

5、0058*56=0.3248I35=0.0062*56=0.3472I41=0.0037*56=0.2072I47=0.0012*56=0.06723.5流入系统谐波电流假设动力系统吸收10%,非特征谐波电流含有率单台整流器特征谐波4Is5=0.9*10.416=9.3744113=0.046*56=2.576I19=0.0142*56=0.7952I25=0.004*56=0.224I31=0.0064*56=0.3584I37=0.0055*56=0.308I43=0.0028*56=0.1568I49=0.0011*56=0.0616其余90%流入系统.5%时特征谐波5%台整流器特征谐波

6、Ish37.49761.8749Is7=0.9*6.944=6.249624.99841.2499Is1仁0.9*3.528=3.175212.70080.6350Is13=0.9*2.576=2.31849.27360.4637Is17=0.9*1.232=1.10884.43520.2218Is19=0.9*0.7952=0.71572.8630.1431ls23=0.9*0.2856=0.25701.02820.0514ls25=0.9*0.224=0.20160.80640.0403Is29=0.9*0.3248=0.292321.16930.05846Is31=0.9*0.3584=

7、0.32261.29020.0645Is35=0.9*0.3472=0.312481.24990.0625Is37=0.9*0.308=0.27721.10880.0544Is41=0.9*0.2072=0.186480.745920.037296Is43=0.9*0.1568=0.14110.56480.02822Is47=0.9*0.0672=0.06480.24190.0121Is49=0.9*0.0616=0.05540.22180.01113.5110kv母线最小短路容量1303.14MVA时，计算各次谐波电压(1)系统阻抗Xs1二U*U/Smin=110*110/1303.14=9

8、.285(2) 计算各次谐波电压Uh=lsh*Xsh=lsh*(h*Xs1)5%非特征谐波电压0.087(KV)0.081(KV)0.065(KV)0.0560.0350.0255特征谐波电压U5=37.4976*(5*9.285)=1.74(KV)U7=24.9984*(7*9.285)=1.625(KV)U11=12.7008*(11*9.285)=1.297(KV)U13=9.2736*(13*9.285)=1.119U17=4.4352*(17*9.285)=0.7U19=2.863*(19*9.285)=0.505U23二1.0282*(23*9.285)=0.220.011U25二

9、0.8064*(25*9.285)=0.1870.01U29=1.1693*(29*9.285)=0.4560.023U31=1.2902*(31*9.285)=0.3710.019U35=1.2499*(35*9.285)=0.4060.02U37=1.1088*(37*9.285)=0.380.02U41=0.74592*(41*9.285)=0.280.014U43=0.5648*(43*9.285)=0.2260.011U47=0.2419*(47*9.285)=0.106U49=0.2218*(49*9.285)=0.101按单机组12脉波，整变相位角相差7.5,4机组等效48脉波.

10、U47、U49为特征谐波电压，其余均为非特征谐波电压。当Kh(f)=5%时，5至49次的总谐波电压畸变率为：THDu=/(0.087+0.081+0.065+0.056+0.035+0.0255+0.011+0.01+0.023+0.019+0.02+0.02+0.014+0.011+0.106+0.101)/110/辺二(0.0076+0.0066+0.0042+0.0031+0.0012+0.0007+0.0001+0.0001+0.0005+0.00036+0.000004+0.0002+0.00012+0.01124+0.0102)/63.5仁).04626/63.51=0.00338

11、657=0.34%4谐波分析和比较根据最小短路容量修正谐波电流允许值15=(1303.14/750)*9.6=1.7375*9.6=16.6817=(1303.14/750)*6.8=1.7375*6.8=11.81511仁(1303.14/750)*4.3=7.47113=(1303.14/750)*3.7=6.43117=(1303.14/750)*2.8=4.865119=(1303.14/750)*2.5=4.34123=(1303.14/750)*2.仁3.648125=(1303.14/750)*1.9=3.3根据最小短路容量修正谐波电流允许值，计算用电协议容量修正谐波电流允许值，

12、220kv隆兴变主变容量为180MVA本站主变容量为50MVA根据修正公式I5i=16.68*(0.278)1/1.2=5.74I11i=7.47(0.278)1/1.8=3.67I17i=4.865(0.278)1/2=2.57I23i=3.648(0.278)1/2=1.923I7i=11.815(0.278)1/1.4=4.73I13i=6.43(0.278)1/1.9=3.28I19i=4.34(0.278)1/2=2.29I25i=3.3(0.278)1/2=1.74注入公共连接点（PCC）110kv谐波电流的允许值谐波次数短路容量/MVA50/180=0.278谐波电流谐波次数短路

13、容量/MVA50/180=0.278谐波电流7501303.147501303.14212.0201.239.6211.446.0221.159.616.685.741.8749232.13.6481.92364.0241.076.811.8154.731.2499251.93.31.7483.02693.227102.428114.37.473.670.635029122.030133.76.433.280.4637141.7151.9161.5172.84.8652.570.2218181.3192.54.342.290.1431注入公共连接点35kv谐波电流的允许值谐波次数短路容量/MV

14、A谐波次数短路容量/MVA250348.75250348.75215.0201.5312.0211.847.7221.4512.0232.765.1241.378.8252.583.82694.127103.128115.629122.630134.7142.2152.5161.9173.6181.7193.2注入公共连接点10kv谐波电流的允许值谐波次数短路容量/MVA谐波次数短路容量/MVA100234.24100234.24226202.632021413225202368.5247152586.42696.827105.128119.329124.330137.9143.7154.1163.2176.0182.8195.4