## Minimise value of variables in MINLP solution

Problems with syntax of GAMS
cargarsan5
User Posts: 2
Joined: 1 month ago

### Minimise value of variables in MINLP solution

Hello everybody,

I have a MINLP problem (BONMIN solver). This problem have some variables (P_size(j), P(j,t)...)

This is the objective function

Code: Select all

``````eqOpt1.. total_cost =e=  sum(j,w_C(j)*SBASE*P_size(j));
``````
and this equation as constraint (and others of electrical problem)

Code: Select all

``````eq10(j,t).. P_size(j) =g= P(j,t);
``````
So in my solution P_size(j) is calculate good, but P(j,t) not choose the minimum value (that is I want), GAMS provide a solution close to the maximum value P_size(j)~P(j,t). How can i do it? I am always interested in having the smallest value of P

Thank you so much

abhosekar
Moderator Posts: 190
Joined: 9 months ago

### Re: Minimise value of variables in MINLP solution

You are minimizing your objective function which contains P_size and that is what you tell the solver to minimize.
To satisfy the constraint, P_size ~ P is enough (it can very well give you the maximum P that satisfies the constraint. It has no incentive to do better). You are not telling the solver anywhere to minimize P.