I believe all of the OPF solvers available to MATPOWER simply solve the first-order optimality conditions, so they find a local minimum. However, in my experience, it is *very* difficult to find multiple local optimal solutions for an OPF problem. I have only found one reproducible example and the real power dispatch and objective function value are nearly identical, with some difference in the voltage and reactive power dispatches. All that to say that, based on my experience, I do not expect to encounter what I would consider a "local minimum problem" with any of MATPOWER's OPF solvers.
-- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Feb 29, 2012, at 10:13 AM, Hongxing Ye wrote: > Thanks for the reply. > Yes. That's what I meant. It can fix the problem. The scenario is as > following: > I use MILP solver to obtain the P and Q for scuc with partial transmission > constraints, and then use Matpower to get the power flow solution. > > By the way, do u encounter local minimum problem when using fmincon to solve > the OPF problem? Thanks! > > Sincerely, > Hongxing Ye > > On Feb 27, 2012, at 9:44 AM, Ray Zimmerman <[email protected]> wrote: > >> And are you suggesting that the lines ... >> >> mx = find( gen(:, GEN_STATUS) > 0 & gen(:, QG) > gen(:, QMAX) ); >> mn = find( gen(:, GEN_STATUS) > 0 & gen(:, QG) < gen(:, QMIN) ); >> >> ... be changed to something like ... >> >> tol = mpopt(16); %% OPF_VIOLATION >> mx = find( gen(:, GEN_STATUS) > 0 & gen(:, QG) > gen(:, QMAX) + tol ); >> mn = find( gen(:, GEN_STATUS) > 0 & gen(:, QG) < gen(:, QMIN) - tol ); >> >> Would that fix the infeasibility issues you are seeing? If so, I'll include >> this change in the next version of MATPOWER. >> >> Just to make sure I understand the issue you are running into, could you >> describe a scenario that leads to infeasibility? >> >> Thanks, >> >> -- >> Ray Zimmerman >> Senior Research Associate >> 419A Warren Hall, Cornell University, Ithaca, NY 14853 >> phone: (607) 255-9645 >> >> >> >> >> On Feb 25, 2012, at 1:32 AM, Hongxing Ye wrote: >> >>> To whom it may concern, >>> In line 149 & 150 of ‘runpf.m’ in version 3.2 or line 218 & 219 in >>> version 4.0, there’s no tolerance for the reactive power limit for >>> generator. Sometimes it may lead to infeasible problem, especially when >>> incorporated with other packages. I just encountered it and report it. >>> Thanks a lot for this great Matlab package. >>> >>> Best regards! >>> Ye Hongxing >>> Ph.D student >>> ECE Dept., Illinois Institute of Technology >>
