短路电流计算

课程设计报告题目：短路电流计算所在学院专业班级学生姓名学生学号指导教师提交日期目录一、计算原理： (1)二、计算流程： (1)三、程序分析： (3)四、短路电流计算主程序输入文件清单： (4)五、导纳矩阵程序输入文件清单： (7)六、整理计算结果： (8)七、短路电流计算的要点： (12)八、体会 (12)附件一： (13)一、计算原理： 基于节点阻抗矩阵用MATLAB 语言编写程序计算图1所示的算例系统的三相短路电流，当4号母线发生金属性三相短路时（z f =0），分别按照精确算法和近似算法计算短路电流、系统中各节点电压以及网络中各支路的电流分布，并对两种情况下的计算结果进行比较。

近似算法是指：形成节点导纳矩阵时，所有节点的负荷都略去不计，短路前网络处于空载状态，短路前各节点电压均为1.0。

图1 三机九节点系统二、计算流程：计算流程框图(0)i Vi I (/i diE x ''''=阻抗的接地支路表示；形成包括所有发电机支路和负荷支路的节点导纳矩阵中的发电机节点和负荷节点的自导纳上分别增加发电机导纳利用，计算节点阻抗矩阵，从而得到阻抗矩阵中的第f列计算短路电流计算系统中各节点电压计算各支路的短路电流乘以IB得到有名值解毕注：计算短路电流以及各端电压请参见附录一。

三、程序分析：为了计算短路电流，那么必须先得出计算导纳矩阵的程序，其中我们需要根据以下导纳矩阵的公式变压器：线路：接地支路：211;11;i ,i i ,i j ,j j ,j i ,j i ,j j ,i j ,i Y Y Y Y R jX k (R jX )Y Y Y Y k(R jX )k(R jX )⎧⎫←+←+⎪⎪++⎪⎪⎨⎬⎪⎪←-←-⎪⎪++⎩⎭11;2211;i ,i i ,i j ,j j ,j i ,j i ,j j ,i j ,i B B Y Y j Y Y j R jX R jX Y Y Y Y R jX R jX ⎧⎫←++←++⎪⎪++⎪⎪⎨⎬⎪⎪←-←-⎪⎪++⎩⎭1i ,i i ,i Y Y R jX ⎧⎫←+⎨⎬+⎩⎭四、短路电流计算主程序输入文件清单：Sbase_MVA=100.fid=fopen('Nodedata.txt');N=textscan(fid, '%s %u %d %f %f %f %f %f %f');fclose(fid);busnumber=size(N{1},1)for i=1:busnumberBus(i).name=N{1}(i);Bus(i).type=N{2}(i);Bus(i).no=i;Bus(i).Base_KV=N{3}(i);Bus(i).PG=N{4}(i);Bus(i).QG=N{5}(i);Bus(i).PL=N{6}(i);Bus(i).QL=N{7}(i);Bus(i).pb=N{8}(i); %接地电抗（或电容）导纳标幺值Bus(i).V=1.0;Bus(i).angle=0;endfid=fopen('Aclinedata.txt');A=textscan(fid, '%s %s %f %f %f %f');fclose(fid);aclinenumber=size(A{1},1)for i=1:aclinenumberAcline(i).fbname=A{1}(i);Acline(i).tbname=A{2}(i);Acline(i).Base_KV=A{3}(i);Acline(i).R=A{4}(i);Acline(i).X=A{5}(i);Acline(i).hB=A{6}(i);for k=1:busnumberif strcmp(Acline(i).fbname, Bus(k).name)Acline(i).fbno=Bus(k).no;endif strcmp(Acline(i).tbname, Bus(k).name)Acline(i).tbno=Bus(k).no;endendendfid=fopen('Transdata.txt');T=textscan(fid, '%s %f %f %s %f %f %f %f');fclose(fid);tansnumber=size(T{1},1)for i=1:tansnumberTrans(i).fbname=T{1}(i);Trans(i).fbBase_KV=T{2}(i);Trans(i).fbrated_KV=T{3}(i);Trans(i).tbname=T{4}(i);Trans(i).tbBase_KV=T{5}(i);Trans(i).tbrated_KV=T{6}(i);Trans(i).R=T{7}(i);Trans(i).X=T{8}(i);for k=1:busnumberif strcmp(Trans(i).fbname, Bus(k).name)Trans(i).fbno=Bus(k).no;endif strcmp(Trans(i).tbname, Bus(k).name)Trans(i).tbno=Bus(k).no;endendTrans(i).k=Trans(i).tbrated_KV*Trans(i).fbBase_KV/Trans(i).fbrated_KV/Trans(i).tbBase_KV; tempx=Trans(i).fbrated_KV^2/Trans(i).fbBase_KV^2;Trans(i).X=tempx*Trans(i).X;Trans(i).R=tempx*Trans(i).R;end[G,B,B2]=FormYmatrix(Bus,busnumber,Acline,aclinenumber,Trans,tansnumber); %B:=B';B2:=B"%dlmwrite('Gmatrix.txt', G, 'delimiter', '\t','precision', 6);%dlmwrite('Bmatrix.txt', B, 'delimiter', '\t','precision', 6);YN=j*B2 %按近似算法所得的节点导纳矩阵，YN不包括发电机导纳和负荷导纳的节点导纳矩阵pausey=1.0/(j*0.15) %每一台发电机的次暂态电抗0.15for i=1:3YN(i,i)=YN(i,i)+y; %将发电机导纳加入节点导纳矩阵end%荷导节点开路YN %包括发电机导纳节点导纳矩阵pauseZ=inv(YN) %Z节点阻抗矩阵%4号节点三相短路If=(Bus(4).V*cos(Bus(4).angle)+j*Bus(4).V*sin(Bus(4).angle))/Z(4,4) %母线对地短路电流标幺值/(0-9.1239)i/puIB=Sbase_MVA/sqrt(3)/230 %0.251kAIfymzh=abs(If*IB) %母线对地短路电流有名值 2.2903kAfor i=1:busnumberV0(i)=Bus(i).V*cos(Bus(i).angle)+j*Bus(i).V*sin(Bus(i).angle);Vf(i)=V0(i)-Z(i,4)*If;I(i)=Vf(i)/Z(i,4);I(i)=abs(I(i)*IB);endpauseV0 %1 1 1 1 1 1 1 1 1Vf %0.2775 0.6769 0.6771 0.0000 0.1874 0.1935 0.5422 0.5459 0.5509Clear五、导纳矩阵程序输入文件清单：function [G,B,X]=FormYmatrix(Bus,busnumber,Acline,aclinenumber,Trans,tansnumber)Y=zeros(busnumber);X=zeros(busnumber);for i=1:busnumberY(i,i)=Y(i,i)+1/j*Bus(i).pb;endfor i=1:aclinenumberf=Acline(i).fbno;t=Acline(i).tbno;Y(f,f)=Y(f,f)+j*Acline(i).hB+1/(Acline(i).R+j*Acline(i).X);Y(t,t)=Y(t,t)+j*Acline(i).hB+1/(Acline(i).R+j*Acline(i).X);Y(f,t)=Y(f,t)-1/(Acline(i).R+j*Acline(i).X);Y(t,f)=Y(t,f)-1/(Acline(i).R+j*Acline(i).X);X(f,f)=X(f,f)-1/Acline(i).X;X(t,t)=X(t,t)-1/Acline(i).X;X(f,t)=1/Acline(i).X;X(t,f)=1/Acline(i).X;endfor i=1:tansnumberf=Trans(i).fbno;t=Trans(i).tbno;Y(f,f)=Y(f,f)+1/(Trans(i).R+j*Trans(i).X);Y(t,t)=Y(t,t)+1/[(Trans(i).R+j*Trans(i).X)/Trans(i).k^2];Y(f,t)=Y(f,t)-1/[(Trans(i).R+j*Trans(i).X)/Trans(i).k];Y(t,f)=Y(t,f)-1/[(Trans(i).R+j*Trans(i).X)/Trans(i).k];X(f,f)=X(f,f)-1/Trans(i).X;X(t,t)=X(t,t)-1/Trans(i).X;X(f,t)=1/Trans(i).X;X(t,f)=1/Trans(i).X;endG=real(Y);B=imag(Y);end六、整理计算结果：Sbase_MVA =100busnumber =9aclinenumber =6tansnumber =3YN =Columns 1 through 50 -17.3611i 0 0 0 +17.3611i 0 0 0 -16.0000i 0 0 0 0 0 0 -17.0648i 0 0 0 +17.3611i 0 0 0 -39.9954i 0+11.7647i0 0 0 0 +11.7647i 0 -17.9759i0 0 0 0 +10.8696i 0 0 0 +16.0000i 0 0 0 +6.2112i0 0 0 0 0 0 0 0 +17.0648i 0 0Columns 6 through 90 0 0 00 0 +16.0000i 0 00 0 0 0 +17.0648i0 +10.8696i 0 0 00 0 + 6.2112i 0 00 -16.7519i 0 0 0 + 5.8824i0 0 -36.1001i 0 +13.8889i 00 0 +13.8889i 0 -23.8095i 0 + 9.9206i0 + 5.8824i 0 0 + 9.9206i 0 -32.8678iy =0 - 6.6667iYN =Columns 1 through 50 -24.0278i 0 0 0 +17.3611i 0 0 0 -22.6667i 0 0 0 0 0 0 -23.7315i 0 0 0 +17.3611i 0 0 0 -39.9954i 0+11.7647i0 0 0 0 +11.7647i 0 -17.9759i0 0 0 0 +10.8696i 0 0 0 +16.0000i 0 0 0 +6.2112i0 0 0 0 0 0 0 0 +17.0648i 0 0Columns 6 through 90 0 0 00 0 +16.0000i 0 00 0 0 0 +17.0648i0 +10.8696i 0 0 00 0 + 6.2112i 0 00 -16.7519i 0 0 0 + 5.8824i0 0 -36.1001i 0 +13.8889i 00 0 +13.8889i 0 -23.8095i 0 + 9.9206i0 + 5.8824i 0 0 + 9.9206i 0 -32.8678iZ =Columns 1 through 50 + 0.0988i 0 + 0.0256i 0 + 0.0256i 0 + 0.0792i 0 +0.0644i0 + 0.0256i 0 + 0.0963i 0 + 0.0281i 0 + 0.0354i 0 +0.0487i0 + 0.0256i 0 + 0.0281i 0 + 0.0963i 0 + 0.0354i 0 +0.0369i0 + 0.0792i 0 + 0.0354i 0 + 0.0354i 0 + 0.1096i 0 +0.0891i0 + 0.0644i 0 + 0.0487i 0 + 0.0369i 0 + 0.0891i 0 +0.1378i0 + 0.0639i 0 + 0.0367i 0 + 0.0494i 0 + 0.0884i 0 + 0.0758i0 + 0.0363i 0 + 0.0739i 0 + 0.0398i 0 + 0.0502i 0 + 0.0690i0 + 0.0360i 0 + 0.0594i 0 + 0.0546i 0 + 0.0498i 0 + 0.0617i0 + 0.0356i 0 + 0.0391i 0 + 0.0753i 0 + 0.0492i 0 + 0.0514iColumns 6 through 90 + 0.0639i 0 + 0.0363i 0 + 0.0360i 0 + 0.0356i0 + 0.0367i 0 + 0.0739i 0 + 0.0594i 0 + 0.0391i0 + 0.0494i 0 + 0.0398i 0 + 0.0546i 0 + 0.0753i0 + 0.0884i 0 + 0.0502i 0 + 0.0498i 0 + 0.0492i0 + 0.0758i 0 + 0.0690i 0 + 0.0617i 0 + 0.0514i0 + 0.1412i 0 + 0.0520i 0 + 0.0590i 0 + 0.0687i0 + 0.0520i 0 + 0.1047i 0 + 0.0842i 0 + 0.0554i0 + 0.0590i 0 + 0.0842i 0 + 0.1227i 0 + 0.0760i0 + 0.0687i 0 + 0.0554i 0 + 0.0760i 0 + 0.1048iIf =0 - 9.1239iIB =0.2510Ifymzh =2.2903Z =Columns 1 through 50 + 0.0988i 0 + 0.0256i 0 + 0.0256i 0 + 0.0792i 0 + 0.0644i0 + 0.0256i 0 + 0.0963i 0 + 0.0281i 0 + 0.0354i 0 + 0.0487i0 + 0.0256i 0 + 0.0281i 0 + 0.0963i 0 + 0.0354i 0 + 0.0369i0 + 0.0792i 0 + 0.0354i 0 + 0.0354i 0 + 0.1096i 0 + 0.0891i0 + 0.0644i 0 + 0.0487i 0 + 0.0369i 0 + 0.0891i 0 + 0.1378i0 + 0.0639i 0 + 0.0367i 0 + 0.0494i 0 + 0.0884i 0 + 0.0758i0 + 0.0363i 0 + 0.0739i 0 + 0.0398i 0 + 0.0502i 0 + 0.0690i0 + 0.0360i 0 + 0.0594i 0 + 0.0546i 0 + 0.0498i0 + 0.0617i0 + 0.0356i 0 + 0.0391i 0 + 0.0753i 0 + 0.0492i 0 + 0.0514iColumns 6 through 90 + 0.0639i 0 + 0.0363i 0 + 0.0360i 0 + 0.0356i0 + 0.0367i 0 + 0.0739i 0 + 0.0594i 0 + 0.0391i0 + 0.0494i 0 + 0.0398i 0 + 0.0546i 0 + 0.0753i0 + 0.0884i 0 + 0.0502i 0 + 0.0498i 0 + 0.0492i0 + 0.0758i 0 + 0.0690i 0 + 0.0617i 0 + 0.0514i0 + 0.1412i 0 + 0.0520i 0 + 0.0590i 0 + 0.0687i0 + 0.0520i 0 + 0.1047i 0 + 0.0842i 0 + 0.0554i0 + 0.0590i 0 + 0.0842i 0 + 0.1227i 0 + 0.0760i0 + 0.0687i 0 + 0.0554i 0 + 0.0760i 0 + 0.1048iIf =0 - 9.1239iIB =0.2510Ifymzh =2.2903V0 =1 1 1 1 1 1 1 1 1Vf =0.2775 0.6769 0.6771 0.0000 0.1874 0.1935 0.5422 0.5459 0.5509I =0.8795 4.7978 4.8020 0.0000 0.5281 0.5493 2.7131 2.7529 2.8096七、短路电流计算的要点：1、对发电机节点在每一发电机节点增加接地有源支路一般情况下发电机定子绕组电阻Ri忽略掉，并将的电压源与阻抗有源支路转化成电流源与导纳并联的支路。