What's wrong with my decoupled power flow program

Question

Nguyen 2014-12-11

0
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https://ww2.mathworks.cn/matlabcentral/answers/166272-what-s-wrong-with-my-decoupled-power-flow-program

编辑： Nguyen 2014-12-11

I have write a decoupled power flow program. The code has no problem. However, my results about the reactive power generation are negative. This should be positive. It seems that unreasonable. Can anyone who are experts in power engineering help me,thank you very much?

m = find(Bus_type ~= 1);
n = find(Bus_type == 3);
p = find(Bus_type == 1);
%Build the B' and B'' matrix
B1 = inv(imag(Y(m,m)));
B2 = inv(imag(Y(n,n)));
%Find the real and reactive power mismatch
theta_est = zeros(length(ID_bus),1); %Initial Estimate of Angle
iteration = 200; %Number of iteration
iter = 1;
%dP = zeros(length(ID_bus),1);
%dQ = zeros(length(ID_bus),1);
%Start iteration
for iter = 1:iteration
P = zeros(length(ID_bus),1);
Q = zeros(length(ID_bus),1);
for i=1:length(ID_bus)
for j=1:length(ID_bus)
P(i) = P(i) + Vhold(i)*Vhold(j)*abs(Y(i,j))*cos(angle(Y(i,j))-theta_est(i)+theta_est(j));
Q(i) = Q(i) - Vhold(i)*Vhold(j)*abs(Y(i,j))*sin(angle(Y(i,j))-theta_est(i)+theta_est(j));
end
end
dP = P_sch(m) - P(m);
dQ = Q_sch(n) - Q(n);
%Find the mismatch Angle
dtheta = -B1*dP./Vhold(m);
%Update the angle
theta_est(m) = theta_est(m) + dtheta;
%Find the mismatch Voltage
dV = -B2*dQ./Vhold(n);
%Update the Voltage
Vhold(n) = Vhold(n) + dV;
%Convergence tolerance
Tolerance = max(max(abs(dP)),max(abs(dQ)));
end