Typically, OPF problems are solved by iterative, numerical methods that employ some termination tolerance. So the solutions are only accurate to within some numerical tolerance. If you need more accuracy, you might try decreasing these tolerances. The details of which parameters to change will depend on the solver you are using.
-- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Feb 21, 2013, at 4:22 AM, Jiashen Teh <[email protected]> wrote: > hi Dr Ray, > > I correct my question, pls ignore my previous questions. > > I add in an expensive generator (cost : 1000) at every load buses and set > their minimum output to be 0. > However, I still get a small fraction of power (to the power of -5) from > these expensive generator. > > May I know why? > > > 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 Jiashen Teh > [[email protected]] > Sent: 21 February 2013 09:01 > To: MATPOWER discussion forum > Subject: RE: Problem when running many iterations > > > Hi Dr Ray, > > Seeing your questions, I check back my results and discover few things. > > I add an extra very expensive generator (10000) at every load buses and > discover that the DCOPF will utilize the expensive generator and the cheap > generator produce negative output. > > How is this so? > > 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: 20 February 2013 20:01 > To: MATPOWER discussion forum > Subject: Re: Problem when running many iterations > > I have a few questions to try to track this down … > > - Is this a power flow or optimal power flow problem you are running? > - If OPF, is it AC or DC? > - Which solver is being used? > - Is it repeatable? Does it always happen at the same point? > - What is the output of 'mpver'? > - What is the full error message with stack trace? > > -- > Ray Zimmerman > Senior Research Associate > 419A Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > > On Feb 20, 2013, at 2:34 PM, Jiashen Teh > <[email protected]> wrote: > >> Hi all, >> >> I use Matpower in Monte Carlo simulations. >> >> when I run MATPOWER for about 1000 times, matlab will display me an error >> message saying trying to access non-structure array. >> >> I have not problems when trying to run it for 3 or 10 iterations. >> >> >> 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 > >
