The power balance equations are included explicitly as equality constraints. See equation A.2 in the manual. They are not handled by solving a separate load flow problem. The latest version 4.0b4 includes a "constrained 4-d non-linear" test problem in t/t_mips.m that includes a non-linear equality constraint.
I'm not sure if this answers your question. -- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jun 1, 2010, at 5:47 PM, b v wrote: Hello, Thank you...yes I had a look at this and also solved an easy optimization problem like those in t-mips.m using mips solver successfully. But by comparing my OPF distribution problem with those in t-mips.m, I face with some difficulties. As you know the equality constraints in OPF are the load flow power balance equations which first should be solved by ac load flow. How can I handle with the load flow part? Many Thanks in advance. Best Regards On Tue, Jun 1, 2010 at 1:41 PM, Ray Zimmerman <[email protected]<mailto:[email protected]>> wrote: Have you looked at the examples in Appendix A in the MATPOWER User's Manual<http://www.pserc.cornell.edu/matpower/manual.pdf>? You can also find a few more examples in t/t_mips.m. It sounds like you have already implemented the objective function and constraint evaluation function for you problem, which includes the gradients. So, the only thing missing is a function for efficiently evaluating the Hessian of the Lagrangian function for your problem. The opf_hessian function computes this for MATPOWER's OPF and the derivation of the formulas used can be found in the MATPOWER Technical Note 2, AC Power Flows, Generalized OPF Costs and their Derivatives using Complex Matrix Notation<http://www.pserc.cornell.edu/matpower/TN2-OPF-Derivatives.pdf>. You may find it helpful in the derivation of the Hessian for your problem. Feel free to ask if you have specific implementation questions. -- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On May 31, 2010, at 5:45 PM, b v wrote: Hello all, I have a project to do OPF for distribution systems. The objective function is to minimizing the Power loss. I have done it already by MATLAB using fmincon function. However, for using mips solver in Matpower and taking the hessian matrix from the opf_hessfcn function I would like to do it in Matpower too. But I do not have any idea how to do it and if it is possible at all. If it works then we can use the matpower for doing OPF in distribution systems as well. Can anyone please explain me simply how I can use Matpower to optimize my own objective function respect to my own constraint. I should add that my data file is exactly same as casedata format in Matpower and just the obj. function and constraints are different. Many Thanks in advance. Best Regards
