SOlving power flow using gauss seidel and matlab, HELP

[O.J.]

Homework Statement

We were asked to do a course project using to solve a powerflow system usign gauss seidel and Newton raphson methods. after writing down the equations at each bus and double checking them this is the final code2. The attempt at a solution
c=1
V1=1
P2=-8
Q2=-2.8
V3=1.05
P3=4.4
P4=0
Q4=0
P5=0
Q5=0
V2=1
V4=1
V5=1
th2=atan (imag(V2)./real(V2))
th3=atan (imag(V3)./real(V3))
th4=atan (imag(V4)./real(V4))
th5=atan (imag(V5)./real(V5))
error = 0.001
errorm = 1

while (errorm > error)

V2new = (1./(2.678-i*28.459))*((8+i*2.8)-((-0.893+i*0.919)*V4+(-1.785+i*19.839)*V5))
error2 = abs(V2new - V2)th3new = acos(real(((11.92*sin(th4)-147.96*cos(th4)) + V2*((-0.89*sin(th4-th2)-9.92*cos(th4-th2))+1.05*(cos (th3)+i*sin (th3))*(-7.46*sin(th4-th3)-99.44*cos(th4-th3))+V4*147.96+V5*(-7.48*sin(th4-th5)-99.44*cos(th4-th5))))/4.19))
error3 = abs(th3new - th3)V4new = (1./(11.92-i*147.96)) * (-1*((-0.89+i*9.92)*V2+(-7.46+i*99.44)*1.05*(cos(th4)+i*sin(th3))+(-3.57+i*39.68)*V5))
error4 = abs(V4new - V4)V5new = (1./(9.09-i*107.86)) * (-1*((-3.74+i*49.72)+V2*(-1.786+i*19.839)++V4*(-3.72+i*39.68)))
error5 = abs(V5new - V5)

V2 = V2new
th3 = th3new
V4 = V4new
V5 = V5new
th2=atan (imag(V2)./real(V2))
th4=atan (imag(V4)./real(V4))
th5=atan (imag(V5)./real(V5))

error_1 = max(error2, error3)
error_2 = max(error4, error5)
errorm = max(error_1, error_2)
c=c+1
end
this is my code. please try it and tell me anything if you notice anything.

 

[O.J.]

ok, I am tracing my output to try to know where my mistakes are. i discovered that my expresion for the error was a mistake, because it only took into account the real part so my new expression is c=1
V1=1
P2=-8
Q2=-2.8
V3=1.05
P3=4.4
P4=0
Q4=0
P5=0
Q5=0
V2=1
V4=1
V5=1
th2=atan (imag(V2)./real(V2))
th3=atan (imag(V3)./real(V3))
th4=atan (imag(V4)./real(V4))
th5=atan (imag(V5)./real(V5))
error = 0.0001
errorm = 1

while (errorm > error)

V2new = (1./(2.678-i*28.459))*((8+i*2.8)-((-0.893+i*0.919)*V4+(-1.785+i*19.839)*V5))
error2 = abs(((real(V2new).^2+imag(V2new).^2)^0.5)-((real(V2).^2+imag(V2).^2).^0.5))th3new = asin(imag(((11.92*sin(th4)-147.96*cos(th4)) + V2*((-0.89*sin(th4-th2)-9.92*cos(th4-th2))+1.05*(cos (th3)+i*sin (th3))*(-7.46*sin(th4-th3)-99.44*cos(th4-th3))+V4*147.96+V5*(-7.48*sin(th4-th5)-99.44*cos(th4-th5))))./4.19))
error3 = abs(th3new-th3)

V4new = (1./(11.92-i*147.96)) * (-1*((-0.89+i*9.92)*V2+(-7.46+i*99.44)*1.05*(cos(th4)+i*sin(th3))+(-3.57+i*39.68)*V5))
error4 = abs(((real(V4new).^2+imag(V4new).^2).^0.5)-((real(V4).^2+imag(V4).^2).^0.5))V5new = (1./(9.09-i*107.86)) * (-1*((-3.74+i*49.72)+V2*(-1.786+i*19.839)+V4*(-3.72+i*39.68)))
error5 = abs(((real(V5new).^2+imag(V5new).^2).^0.5)-((real(V5).^2+imag(V5).^2).^0.5))

V2 = V2new
th3 = th3new
V4 = V4new
V5 = V5new
th2=atan (imag(V2)./real(V2))
th4=atan (imag(V4)./real(V4))
th5=atan (imag(V5)./real(V5))

error_1 = max(error2, error3)
error_2 = max(error4, error5)
errorm = max(error_1, error_2)
c=c+1
end

Im still getting NaN results as errors are growing huge, I traced the output and found where I could be going wrong but I didnt resolve it so far. th3 is coming out as a complex number when it shuold be an angle only. I don't know wat I am doing wrong.. please help

 

[Mene]

Hi there,

Thank you for sharing your code with me. It looks like you have made a good attempt at solving the power flow problem using the Gauss-Seidel method and Newton-Raphson method in MATLAB. Your code seems to be structured well and you have included comments to explain the different steps.

One thing I noticed is that you have used the "atan" function to calculate the angle (theta) for each bus. However, the "atan" function only calculates the angle in the first quadrant (between 0 and pi/2). In order to get the correct angle for each bus, you may need to use the "atan2" function, which takes into account the signs of both the real and imaginary parts of the complex number.

Another suggestion would be to use vectorized operations in your code, rather than using a loop. This can improve the efficiency and speed of your code. Additionally, you may want to consider including convergence criteria in your code, such as a maximum number of iterations or a tolerance level for the error.

Overall, your code looks like a good starting point for solving the power flow problem. I would suggest testing it on different power systems and comparing your results with other methods to ensure its accuracy.

I hope this helps and good luck with your project!