i dunno why it run until 4th iteration then stopped...can anybody help me? it did not give any error...

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Dennis Ting
Dennis Ting 2012-4-23
clc
fprintf('\n\n')
Vb=230e3;
Sb=100e6;
Zb=Vb^2/Sb;
% From To R X
ldata=[1 2 12.333/Zb 0.0933*2*pi*60/Zb
1 4 8.256/Zb 0.1056*2*pi*60/Zb
2 3 6.328/Zb 0.0833*2*pi*60/Zb
2 6 15.696/Zb 0.1696*2*pi*60/Zb
3 5 5.839/Zb 0.0771*2*pi*60/Zb
4 5 10.581/Zb 0.1129*2*pi*60/Zb
4 7 5.993/Zb 0.0537*2*pi*60/Zb
4 8 9.673/Zb 0.1055*2*pi*60/Zb
5 8 7.996/Zb 0.1299*2*pi*60/Zb
6 7 16.395/Zb 0.1753*2*pi*60/Zb
6 8 5.839/Zb 0.0771*2*pi*60/Zb
7 8 6.566/Zb 0.0818*2*pi*60/Zb]
fb=ldata(:,1);
tb=ldata(:,2);
R=ldata(:,3);
X=ldata(:,4);
nbranch=length(ldata(:,1));
nbus=max(max(fb),max(tb));
Z=R+i*X;
y=ones(nbranch,1)./Z;
Y=zeros(nbus,nbus);
ydata=[ldata(:,1),ldata(:,2),y];
for k=1:nbranch;
if fb(k) > 0 && tb(k) > 0
Y(fb(k),tb(k))=Y(fb(k),tb(k))-y(k);
Y(tb(k),fb(k))=Y(fb(k),tb(k));
end
end
for n=1:nbus;
for k=1:nbranch;
if fb(k)==n||tb(k)==n
Y(n,n)=Y(n,n)+y(k);
else end
end
end
y12=ydata(1,3);
y14=ydata(2,3);
y23=ydata(3,3);
y26=ydata(4,3);
y35=ydata(5,3);
y45=ydata(6,3);
y47=ydata(7,3);
y48=ydata(8,3);
y58=ydata(9,3);
y67=ydata(10,3);
y68=ydata(11,3);
y78=ydata(12,3);
s1pu=-(125+i*100)/100;
p3pu=200/100;
s5pu=-(100+i*85)/100;
s6pu=-(150+i*100)/100;
s7pu=-(80+i*75)/100;
s8pu=-(130+i*115)/100;
v1=1.00;
v2=1.03;
v3=1.02;
v4=1.04;
v5=1.00;
v6=1.00;
v7=1.00;
v8=1.00;
dv1=10;
dv3=10;
dv5=10;
dv6=10;
dv7=10;
dv8=10;
iter=0;
disp('iter v1 v3 v5 v6 v7 v8 abs(dv1) abs(dv3) abs(dv5) abs(dv6) abs(dv7) abs(dv8)')
while abs(dv1)>=0.00001 && abs(dv3)>=0.00001 && abs(dv5)>=0.00001 && abs(dv6)>=0.00001 && abs(dv7)>=0.00001 && abs(dv8)>=0.00001 && iter<100
iter=iter+1;
v11=(conj(s1pu)/conj(v1)+y12*v2+y14*v4)/(y12+y14);
dv1=v11-v1;
v1=v11;
Q3=-imag(conj(v3)*(v3*(y23+y35)-y23*v2-y35*v5));
v31=(((p3pu-i*Q3)/conj(v3))+y23*v2+y35*v5)/(y23+y35);
vr3=sqrt(abs(v3)^2-(imag(v31)^2));
VR3=vr3+i*imag(v31);
dv3=VR3-v3;
v3=VR3;
v51=(conj(s5pu)/conj(v5)+y35*v3+y45*v4+y58*v8)/(y35+y45+y58);
dv5=v51-v5;
v5=v51;
v61=(conj(s6pu)/conj(v6)+y26*v2+y67*v7+y68*v8)/(y26+y67+y68);
dv6=v61-v6;
v6=v61;
v71=(conj(s7pu)/conj(v7)+y47*v4+y67*v6+y78*v8)/(y47+y67+y78);
dv7=v71-v7;
v7=v71;
v81=(conj(s8pu)/conj(v8)+y48*v4+y58*v5+y68*v6+y78*v7)/(y48+y58+y68+y78);
dv8=v81-v8;
v8=v81;
fprintf('%g',iter),disp([v1,v3,v5,v7,v8,abs(dv1),abs(dv3),abs(dv5),abs(dv6),abs(dv7),abs(dv8)]);
end
v=[v1,v2,v3,v4,v5,v6,v7,v8];
for i=1:8;
if imag(v(i))>=0
fprintf('v%g=%2.4f+%2.4f*i pu \n',i,real(v(i)),imag(v(i)));
else
fprintf('v%g=%2.4f%2.4f*i pu \n',i,real(v(i)),imag(v(i)));
end
end
  1 个评论
Geoff
Geoff 2012-4-23
Please at least edit this question, highlight all the code and hit the 'code' button in the toolbar. Also, define 'stopped'. Did it give an error message, or did the loop complete cleanly (despite unexpectedly)?

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采纳的回答

Richard Brown
Richard Brown 2012-4-23
OK, with the disclaimer that what you have there isn't a particularly optimal way to write this code, you can fix your problem by replacing all of the && in the while line with || - your code is exiting when one component of the solution has converged, you should be watching for the worst component to have converged. (Oh, but don't modify the && for the iter expression). i.e.:
while iter < 100 && (abs(dv1)>=0.00001 || abs(dv3)>=0.00001 || abs(dv5)>=0.00001 || abs(dv6)>=0.00001 || abs(dv7)>=0.00001 || abs(dv8)>=0.00001)

更多回答（2 个）

Richard Brown
Richard Brown 2012-4-23
You're going to struggle to get someone to answer (let alone read) this question.
I would suggest using the debugger to step through your code one line at a time (to do this, click on a line of code and hit F12, next time you run it will stop here and you can advance it a line at a time using F10) and see if the values at each line are what you expect.
Richard Brown
Richard Brown 2012-4-23
It stops because dv1 drops below its threshhold, causing the loop to quit.
  3 个评论
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Dennis Ting
Dennis Ting 2012-4-23
i am doing the load flow analysis, need to find the value of voltage by using the gauss seidel...but with this, i havent get a constant voltage then the loop already stop...

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