Updating an Iteration with new value

Hello everone,

I am trying to solve an equation of which i need to be using the new values of V and delta as an update in equations (1). Please which one of equations (2 & 3) is the correct updating code for new values;

% P(i) = sum(j=1->n) |Vi||Vj|(Gij * cos(delta_i - delta_j) + Bij * sin(delta_i - delta_j) equation (1) % The formula for calculating the P

Implementation of P(2) for example:

P(2) = P(2) + V(2)*V(1)*(G(2,1)*cos(delta(2)-delta(1)) + B(2,1)*sin(delta(2)-delta(1))) + V(2)*V(2)*(G(2,2)*cos(delta(2)-delta(2)) + B(2,2)*sin(delta(2)-delta(2))) + V(2)*V(3)*(G(2,3)*cos(delta(2)-delta(3)) + B(2,3)*sin(delta(2)-delta(3))) + V(2)*V(4)*(G(2,4)*cos(delta(2)-delta(4)) + B(2,4)*sin(delta(2)-delta(4))) + V(2)*V(5)*(G(2,5)*cos(delta(2)-delta(5)) + B(2,5)*sin(delta(2)-delta(5)))

THANK YOU

   Vprev = V;
    deltaprev = delta   

........................................................................................................

    for i = 1:5
        for j = 1 : 5
            P(i) = P(i) + V(i)*V(j)*(G(i,j)*cos(delta(i)-delta(j)) +  B(i,j)*sin(delta(i)-delta(j)))        equation (2)
        end
    end

OR

    for i = 1:5
        for j = 1 : 5
            P(i) = V(i)*V(j)*(G(i,j)*cos(delta(i)-delta(j)) +  B(i,j)*sin(delta(i)-delta(j)))           equation (3)
        end
    end      
    

[Torsten]

You asked this question before, but it is still unclear what the equations and what the unknowns are.

P(i) = sum(j=1->n) |Vi||Vj|(Gij * cos(delta_i - delta_j) + Bij * sin(delta_i - delta_j) (1<=i<=5)

defines e.g. 5 equations.

What are known values and what are the 5 unknowns ?

[Kamilu Sanusi]

@Torsten, thank you for your reply. This question is similar but not the same with the initial post. This is just a question of which one of equations 2 & 3 is correct, e.g

P(i) = formula....

P(i) = P(i) + formula...

if I want to be updating the unknown variables in the formula, do i still need to add P(i) or not necessary

Thank you

[Torsten]

please could you send me your email to [e-mail] so that i send the code

Sorry, no.

P(i) = P(i) + formula...

cannot be correct because you add things to (the old) P(i) instead of updating it.

But setting

P(i) = formula ...

is also quite strange as an update because P(i-1) does not appear in the formula.

So I asked you to simply answer the question what your equations are and what variables you want to solve for.

Knowing this is necessary to answer your question.

[Image Analyst]

"i need to be using the new values of V and delta as an update in equations (1)" So, how in your loop are you obtaining new arrays for V and delta? I don't see them changing anywhere in the loop, you're simply accessing different (row, column) entries for the same old V and delta matrices.

[Torsten]

You set delta(3) to a logical value (true or false) ?

if i == 3
    delta(i) = V_ang(i) == 0;
end

And you modify delta(2) here although you said it is determined by an equation ?

if i == 2              % U may check for possible rror here
    delta(i) = delta(i) + delta(4);
end

[Kamilu Sanusi]

@Torsten, yes, I set node 3 to 0 as the ground node

[Torsten]

So delta(3) should be = 1 if V_ang(3) = 0 and = 0 if V_ang(3) ~= 0 ?

[Kamilu Sanusi]

@Torsten, the program is correct uptill the end of

G = real(YBUS); % conductance (G) <- real part of admittance

B = imag(YBUS) % susceptance (B) <- the imaginary part of admittance

The problem may be from the way I am using the constraints and may be initialization

# % Computing V

[Kamilu Sanusi]

@Torsten

delta_ij = delta_i - delta_j same with delta(i,j) = delta(i) - delta(j)

[Kamilu Sanusi]

@Image Analyst, Please any input?