Dear community,

Hi. I have written a very simple OPF myself with objective function of loss
minimization and I compared my results with matpower standard opf results.

My OPF program:

- Input data : 'case6ww' in matpower
- *ObjFcn = ∑Pg - ∑Pd*
*- **∑Pd = const*
-  Flow limits  : not considered in my program
-  Solver : fmincon

Matpower Standard OPF program

- Flow limits:  not considered  so : rateA = 0 for all lines
- Solver : MIPS
- generator cost data : My question

I am only getting the same answer when mpc.gencost is like below :


%% generator cost data
% 1 startup shutdown         n x1 y1 ... xn yn
% 2 startup shutdown  n c(n-1) ... c0
mpc.gencost = [
2 0               0                     2 *1*           *0*;
2 0               0                     2 *1 *          *0*;
2 0               0                     2 *1*           *0*;
];

However, in FAQs of website it is mentioned that for loss minimization
 "*Assign positive, constant, equal costs to all generators*"
which  means I think:

%% generator cost data
% 1 startup shutdown         n x1 y1 ... xn yn
% 2 startup shutdown  n c(n-1) ... c0
mpc.gencost = [
2 0               0                     2 *0*           *1*;
2 0               0                     2 *0*           *1*;
2 0               0                     2 *0*           *1*;
];

In this case my results are different.

I think costs should not be constant. It should be linear and P dependent
like :

C(P1) = P1
C(P2) = P2
C(P3) = P3

So Objective function becomes :

Objective_costfcn =  P1+P2+P3 = *∑Pg*

*Can anyone help me to understand this problem and fix my own program?*


*Best Wishes,*
*Ehsan*

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