Dear Ray, Thank you very much for your help. The function checklimits() has helped us a lot. Seems like the main issue is that the line loadings are breached.
Regards, Willem Esterhuizen ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Wednesday, June 16th, 2021 at 3:53 PM, Ray Daniel Zimmerman <[email protected]> wrote: > Hi Willem, > > Have you checked that the power flow solution satisfies all of the OPF > constraints? I’m thinking specifically the voltage, branch flow and generator > active and reactive limits. The power flow does not take into account these > OPF limits, and I suspect there are violations. You may find the > checklimits() function in the extras/misc directory to be helpful here. You > can use it as follows: > > r = runpf(<your_case>); > checklimits(r); > > Hope this helps, > > Ray > >> On Jun 11, 2021, at 11:11 AM, Willem Esterhuizen <[email protected]> >> wrote: >> >> Dear MATPOWER community, >> >> I have an initial power flow solution for an mpc case file obtained via >> runpf(). >> >> If I then invoke runopf() with quadratic or linear cost on power generation >> the solver exits without a solution. This is very strange because there >> exists a feasible solution which I compute with runpf(), and with which I >> start runopf(). >> >> I have considerably relaxed the bounds on PMAX, PMIN, QMAX, QMIN, VMAX, VMIN >> on all entries of mpc.bus and mpc.gen. I have tried FMINCON and MIPS. >> >> Some more information: this phenomenon occurs for the grids from the >> Simbench project: https://simbench.de/en/ (at least, I tried it for 5 >> different grids and they all gave the same result). The original data is in >> csv, but available in pandapower via the simbench package. The OPFs also do >> not converge in pandapower. I exported the pandapower instances to Matpower >> mpc cases to test in Matlab. >> >> Any help would be greatly appreciated. Please see details of the error >> messages below. >> >> Regards, >> >> Willem >> >> My errors in Matlab: >> >> The grid has 1 generator and 102 loads. The initial feasible point for the >> generator is: >> Bus Voltage Generation Load >> # Mag(pu) Ang(deg) P (MW) Q (MVAr) P (MW) Q (MVAr) >> ----- ------- -------- -------- -------- -------- -------- >> 1 1.025 0.000* -31.63 12.20 - - >> >> If I use the MIPS solver I get: >> >> Warning: Matrix is close to singular or badly scaled. Results may be >> inaccurate. RCOND = 1.960342e-29. >> >> Numerically Failed >> >> Did not converge in 16 iterations. >> >>>>>>> Did NOT converge (0.56 seconds) <<<<< >> >> If I use FMINCON I get: >> >> MATPOWER Version 7.1, 08-Oct-2020 -- AC Optimal Power Flow >> AC OPF formulation: polar voltages, power balance eqns >> >> Converged to an infeasible point. >> >> fmincon stopped because the size of the current step is less than >> the value of the step size tolerance but constraints are not >> satisfied to within the value of the constraint tolerance. >> >> <stopping criteria details> >> >>>>>>> Did NOT converge (2.25 seconds) <<<<< >> >> mpc.gen for this infeasible point returned by FMINCON reads: >> >> 1.0000 -28.7893 21.6434 300.0000 -300.0000 0.5739 1.0000 1.0000 200.0000 >> -200.0000 >> >> where the entries are: bus Pg Qg Qmax Qmin Vg mBase status Pmax Pmin, in >> that order.
