Originally posted by: patrijuvet

Hi it's  1 months now that I tried to write a code for unit commitment but i'm always blocked somewhere.

can some body help me to correct my program or send me an exemple of unit commitment problem?

I've attached my code,

This is two problem that i'm facing now

1) cplex signal error to my objective function (1)

2) I dont know how to write constraint (9)

Thank you for you help

Hi

You may find a unit commitment example at http://www.ibm.com/support/knowledgecenter/SSQVNT_3.9.0/ilog.odms.ide.odm.enterprise.help/ODME/ODM_Studio/Demo_UCP/topics/UCP_Top2Welcome.html

In order to fix your objective,

you may use Constraint Programming and then add using CP; at the top of your model and then turn your dvar float into dvar float

Or if you choose linear programming, what you could do is add a new decision variable PX

dvar float+ PX[I][T];

and then add in the subject to block 2 logical constraints

  forall (i in I ,t in T) (X[i][t]==1)=>(PX[i][t]==P[i][t]) ;
  forall (i in I ,t in T) (X[i][t]==0)=>(PX[i][t]==0) ;

and then rewrite your objective into

maximize
 
  sum (t in T, i in I) (P[i,t]*SP[t])*X[i,t]
  -  sum (t in T, i in I) (r*R[i,t]*RP[t])*X[i,t]
  - (1-r)* ( sum(t in T, i in I) (a[i]*X[i,t] + b[i]*P[i,t]*X[i,t] + c[i]*P[i,t]*PX[i,t] )) - (r)* ( sum(t in T, i in I) (a[i] + b[i]*(P[i,t]+R[i,t]) + c[i]*(P[i,t]+R[i,t] )^2)  );
                            

regards

Originally posted by: patrijuvet

Thank you very much for all what you done for US in this forum.

For that ODM_STUDIO, I dont have it , I have tried to seach but I dont found it, plesase can  you help me  how to get that ODM_studio or send  me just the code of the unit  commitment exemple?

Thank you...

Hi

Decision Optimization Centre at http://www-03.ibm.com/software/products/en/decision-optimization-center

See https://twitter.com/AlexFleischer1/status/759041552736026624

regards

Originally posted by: patrijuvet

Hi! I've followed the link to IBM but  I'm not able to download Décision optimisation center. They ask me my site number , and I dont have it. May the software is not free for student

Hi,

indeed IBM Decision Optimization Centre is not free for students

regards

Originally posted by: patrijuvet

OK,Thank  you!

Please can you help me to write that constraint "9"?

Originally posted by: patrijuvet

Hi!  How can I change dvar float onto dvar float? I've tried  to add a dvar float+ PX[I][T]; but I still have the same error : CPLEX Error 5002: ' ct1("Pth1")("1")' is not convex

Originally posted by: ChrisBr

Hello Patrick,

There was a typo in Alex's answer.
You should read
 "turn your dvar float into dvar int".

Regards,

Chris.

Hi

indeed thanks @ChrisBr a22db77d-c4c3-4036-a90f-2e2a20ecec65​ , there was a typo.

Now if you want to go with linear programming what you could do in order to get rid of the convexity error:

Rewrite ct1 into

// Demand load balance     (2)
 forall (i in I ,t in T) {
 ct1:
 sum(i in I) PX[i][t] <=PD[t] ;

Do what you did for P but now for R:

dvar float+ RX[I][T]; // Reserve generation

and then

forall (i in I ,t in T) (X[i][t]==1)=>(RX[i][t]==R[i][t]) ;
  forall (i in I ,t in T) (X[i][t]==0)=>(RX[i][t]==0) ;

and then turn ct3 into

//Spinning reserve        (4)
  forall (i in I, t in T) {
 ct3:
 sum(i in I) RX[i,t] <= SR[t] ;

And then at the top of your model

execute
{
cplex.solutionTarget=3;
}

regards