Just a guess: OPF observes limits QMIN and QMAX on generators, while a powerflow (with the standard option pf.enforce_q_lims=0) does not. Although not typical, it is certainly possible for a powerflow case to be infeasible when solving without generator MVAR limits, and solvable when enforcing them.
Take a look at your OPF solution and check if there are many generators pegged at their Q limits or not. -- Jose L. Marin Grupo AIA 2016-09-08 14:45 GMT+02:00 Gamze Dogan <[email protected]>: > Thank you for your answer, > > > I double check and my OPF does really converge. I also checked the buses > and all my generators are PV and all my non-generators buses are PQ . > I have zero island. If anyone else has an idea why I do not converge even > if my opf converge? > > Thank you, > > > Regards, > > > Dogan > > > ------------------------------ > *De :* [email protected] < > [email protected]> de la part de Abhyankar, > Shrirang G. <[email protected]> > *Envoyé :* mercredi 7 septembre 2016 14:16 > > *À :* MATPOWER discussion forum > *Objet :* Re: Problem with runcpf > > Are you sure the OPF converged? If it did, then I guess you are not > setting the bus types correctly or there is still some error in your system > data. Note that the first step of a continuation power flow is running a > load flow. So if the load flow does not converge then continuation power > flow will not either. > > On Sep 5, 2016, at 9:52 AM, Gamze Dogan <[email protected]> wrote: > > Thank you for your answer, > > > I actually had an island, but the problem remains. Now I am sure that > there are no island. > > The load flow does not converge. > I tried to launch a fast decoupled, but it does not converge. > The OPF converged and I used the results of Vm and Va as the initial guess > to relauch my load flow, but it still does not converge. > > > > > I tried to check the system load using runcpf, but it does not converge, > here is the message: > > MATPOWER Version 5.1, 20-Mar-2015 -- AC Continuation Power Flow > step 1 : lambda = 26502.011, corrector did not converge in 10 iterations > > >>>>> Did NOT converge (0.20 seconds) <<<<< > > Do you have any suggestion on how I can make it converge? > > Thank you, > > Dogan > > > ------------------------------ > *De :* [email protected] < > [email protected]> de la part de Abhyankar, > Shrirang G. <[email protected]> > *Envoyé :* vendredi 2 septembre 2016 13:42 > *À :* MATPOWER discussion forum > *Objet :* Re: Problem with runcpf > > I suspect you have isolated buses or islands that do not have a swing bus. > Have you tried I-iv in MatPower faq on power flow divergence. > > http://www.pserc.cornell.edu/matpower/#pfconvergence > > Shri > > On Sep 2, 2016, at 6:51 AM, Gamze Dogan <[email protected]> wrote: > > Dear all, > > I have a problem when using runpf which does not converge. Therefore, I > tried to check if the system load exceeded the steady-state loading limit > (as mentionned on the website) > > *define_constants; > mpcbase = loadcase('casefile'); > mpcbase.bus(:, PD) = 0; > mpcbase.bus(:, QD) = 0; > mpcbase.gen(:, PG) = 0; > mpctarget = loadcase('casefile'); > results = runcpf(mpcbase, mpctarget); > results.cpf.max_lam > *But I have a problem using the function runcpf, it gives me the following > error message: > > Warning: Matrix is singular to working precision. > > In cpf_corrector at 124 > In runcpf at 257 > step 1 : lambda = NaN, corrector did not converge in 10 iterations > ??? NaN's cannot be converted to logicals. > > Error in ==> printpf at 175 > nzld = find((bus(:, PD) | bus(:, QD)) & bus(:, BUS_TYPE) ~= NONE); > > Error in ==> runcpf at 392 > printpf(results, 1, mpopt); > > I do not understand what the problem is. Any suggestion is wellcome. > > Thank you, > > G. Dogan > > >
