How to solve Gauss seidel power flow solution using matlab - matlab

Question

Hi I am trying to make program for a Gauss seidel power flow solution using matlab and i am facing an error in line 55.
"Error in ==> gauss at 55
[ybus,ych]=ybus;"
How to solve this error? I already tried by adding the function "ybus" but still this error is occurring
% Function ybus
% THIS IS THE PROGRAM FOR CREATING Ybus MATRIX.
function [yb,ych]=ybus
% The line impedances are
zz=[0 0.02+0.1i 0 0 0.05+0.25i
0.02+0.1i 0 0.04+0.2i 0 0.05+0.25i
0 0.04+0.2i 0 0.05+0.25i 0.08+0.4i
0 0 0.05+0.25i 0 0.1+0.5i
0.05+0.25i 0.05+0.25i 0.08+0.4i 0.1+0.5i 0];
% The line chargings are
ych=j*[0 0.03 0 0 0.02
0.03 0 0.025 0 0.020
0 0.025 0 0.02 0.01
0 0 0.02 0 0.075
0.02 0.02 0.01 0.075 0];
% The Ybus matrix is formed here
for m=1:5
for n=1:5
if zz(m,n) == 0
yb(m,n)=0;
else
yb(m,n)=-1/zz(m,n);
end
end
end
for m=1:5
ysum=0;
csum=0;
for n=1:5
ysum=ysum+yb(m,n);
csum=csum+ych(m,n);
end
yb(m,m)=csum-ysum;
end
% Program loadflow_gs
% THIS IS A GAUSS-SEIDEL POWER FLOW PROGRAM
clear all
d2r=pi/180;w=100*pi;
% The Y_bus matrix is
[ybus,ych]=ybus;
g=real(ybus);b=imag(ybus);
% The given parameters and initial conditions are
p=[0;-0.96;-0.35;-0.16;0.24];
q=[0;-0.62;-0.14;-0.08;-0.35];
mv=[1.05;1;1;1;1.02];
th=[0;0;0;0;0];
v=[mv(1);mv(2);mv(3);mv(4);mv(5)];
acc=input('Enter the acceleration constant: ');
del=1;indx=0;
% The Gauss-Seidel iterations starts here
while del>1e-6
% P-Q buses
for i=2:4
tmp1=(p(i)-j*q(i))/conj(v(i));
tmp2=0;
for k=1:5
if (i==k)
tmp2=tmp2+0;
else
tmp2=tmp2+ybus(i,k)*v(k);
end
end
vt=(tmp1-tmp2)/ybus(i,i);
v(i)=v(i)+acc*(vt-v(i));
end
% P-V bus
q5=0;
for i=1:5
q5=q5+ybus(5,i)*v(i);
end
q5=-imag(conj(v(5))*q5);
tmp1=(p(5)-j*q5)/conj(v(5));
tmp2=0;
for k=1:4
tmp2=tmp2+ybus(5,k)*v(k);
end
vt=(tmp1-tmp2)/ybus(5,5);
v(5)=abs(v(5))*vt/abs(vt);
% Calculate P and Q
for i=1:5
sm=0;
for k=1:5
sm=sm+ybus(i,k)*v(k);
end
s(i)=conj(v(i))*sm;
end
% The mismatch
delp=p-real(s)';
delq=q+imag(s)';
delpq=[delp(2:5);delq(2:4)];
del=max(abs(delpq));
indx=indx+1;
if indx==1
pause
end
end
'GS LOAD FLOW CONVERGES IN ITERATIONS',indx,pause
'FINAL VOLTAGE MAGNITUDES ARE',abs(v)',pause
'FINAL ANGLES IN DEGREE ARE',angle(v)'/d2r,pause
'THE REAL POWERS IN EACH BUS IN MW ARE',(real(s)+[0 0 0 0 0.24])*100,pause
'THE REACTIVE POWERS IN EACH BUS IN MVar ARE',(-imag(s)+[0 0 0 0 0.11])*10