Try using the solution of the power flow as the initial guess for OPF. The initial guess, with the mips solver, is computed in mipsopf_solver. Please send your case file if you still have problems.
Shri From: Angelina <[email protected]<mailto:[email protected]>> Reply-To: MATPOWER discussion forum <[email protected]<mailto:[email protected]>> Date: Wed, 29 Jan 2014 22:05:48 +0000 To: 'MATPOWER discussion forum' <[email protected]<mailto:[email protected]>> Subject: RE: numerically failed opf Dear Dr Zimmerman, Shri I tried also with the other solvers (like PDIM,SCDIPM,TRALM) but the problem cannot have a solution. Even when I relax the voltage constraints ( from [0.94-1.06] to [0.9-1.1]) nothing changes. Additionally, even when I have the problem in its simplest form, that is only one slack bus with the grid infeed and no other generators in the rest of the nodes the problem does not converge. When I run the same problem with power flow it converged normally, without any violations. This confuses me a lot. Could I send you the case file and have a look at it? I would be really grateful if you could help me. Regards, Angelina From: [email protected]<mailto:[email protected]> [mailto:[email protected]] On Behalf Of Abhyankar, Shrirang G. Sent: 29 January 2014 15:53 To: MATPOWER discussion forum Subject: Re: numerically failed opf The numerical divergence could also possibly be due to the infeasibility of the problem. Can you try relaxing some of the constraints (especially the voltage magnitude constraints) and see if the OPF converges? Switching to another solver is also an option. See the list of available optimization packages that MATPOWER supports here http://www.pserc.cornell.edu//matpower/#optionalpackages<http://www.pserc.cornell.edu/matpower/#optionalpackages> These archive threads may be relevant for your problem. http://www.mail-archive.com/[email protected]/msg02915.html http://www.mail-archive.com/[email protected]/msg01298.html Shri From: Angelina <[email protected]<mailto:[email protected]>> Reply-To: MATPOWER discussion forum <[email protected]<mailto:[email protected]>> Date: Wed, 29 Jan 2014 15:35:23 +0000 To: MATPOWER discussion forum <[email protected]<mailto:[email protected]>> Subject: numerically failed opf Dear Dr Zimmerman, I am trying to solve an ac opf with the mips solver (560) in a lightly meshed 6.6 kV distribution system of 32 branches. The range for the reactances is [0.05-1.9 pu], whereas some of them have almost negligible values. When I am solving the simple ac power flow the problem converges with no problems to be appeared. However, when I am trying to solve the same problem with optimal power flow, assigning some costs to the generators, the ac opf fails numerically or the message ‘ the matrix is singular to working precision, the results may be inaccurate’ appears. I suspect that the problem is the solver. Could you recommend me another solver to use? Any guidance would be appreciated. Kind Regards, Angelina
