Dear Dr Ray, Insightful as always!
However, I wish to understand more about your statement "ensure that there is a voltage reference bus in each island" Take the IEEE 24 bus network for example, Does Bus 14 , the reference bus is an example of voltage reference bus in a huge island? In this case, the island is 24 bus network. Yours sincerely, Jiashen Teh PhD Student Electrical Energy & Power Systems Group, School of Electrical & Electronic Engineering Ferranti Building (B18), The University of Manchester, M13 9PL, United Kingdom Tel: +44 (0) 161 306 2263; Mobile: +44 (0) 792 322 4864 ________________________________ From: [email protected] [[email protected]] on behalf of Ray Zimmerman [[email protected]] Sent: 22 February 2013 19:15 To: MATPOWER discussion forum Subject: Re: Problems after certain loops The first issue is most likely related to switching off a transmission line and by so doing creating a disconnected network. MATPOWER should be able to handle this case if you can ensure that there is a voltage reference bus in each island. In the second case, there is no longer any network. In theory, such a problem should have a solution if all buses are converted to reference buses, but that is such a degenerate case that I'm nearly certain MATPOWER will not be able to handle it. I'm afraid you'll have to find a different way to solve that problem. -- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Feb 22, 2013, at 10:42 AM, Jiashen Teh <[email protected]<mailto:[email protected]>> wrote: Dear Dr Ray, May I know why I have this error message as follow: Error using opf_model/add_constraints (line 102) @opf_model/add_constraints: number of columns of A does not match number of variables, A is 24 x 71, nv = 72 Error in opf_setup (line 228) om = add_constraints(om, 'Pmis', Amis, bmis, bmis, {'Va', 'Pg'}); %% nb Error in opf (line 219) om = opf_setup(mpc, mpopt); Error in runopf (line 96) [r, success] = opf(casedata, mpopt); Error in rundcopf (line 94) [varargout{1:nargout}] = runopf(casedata, mpopt, fname, solvedcase); I run DCOPF for few thousand loops. Randomly at certain iterations only, i will have the above message shown. During each iterations, i will randomly switch on and off certain generators and transmission line. The weird thing is that I only have problems at certain particular iteration(s) and not before or after the problematic iteration. May I know why? Thanks in advance. On Second issue, i think this is related as well. I add an additional expensive generator at all load buses with sufficient generation to meet the load and disable all transmission lines. when I run DCOPF in this condition, MATLAB will show me "exceeds matrix index error message". Yours sincerely, Jiashen Teh PhD Student Electrical Energy & Power Systems Group, School of Electrical & Electronic Engineering Ferranti Building (B18), The University of Manchester, M13 9PL, United Kingdom Tel: +44 (0) 161 306 2263; Mobile: +44 (0) 792 322 4864
