Besides the good suggestions you got from others, you may also want to try a different solver. I assume you are using the default MIPS solver. Sometimes it does encounter numerical trouble where other algorithms do not. I haven't had the opportunity to dig into things to understand under what circumstances this happens.
-- Ray Zimmerman Senior Research Associate 211 Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Jun 29, 2011, at 8:51 AM, Fanjun Meng wrote: > The voltage is given 4.16kV. I convert the impedances to p.u. by myself with > 1MVA base. Actually I have checked this model in 'runpf()' and the result is > almost the same as shown in IEEE 123 node profile. So I guess the problem > might be the generation cost setting. I'm trying to fix that problem. > > Thank you very much! > > > Fanjun Meng > Electrical Engineering > Missouri University of Science & Technology > [email protected] > > > > On Wed, Jun 29, 2011 at 2:39 AM, Simon Schneider <[email protected]> > wrote: > Are the nodal voltage limits set wide enough(e.g. 0.9 an 1.1)? > Another possible source could be a bad choice of baseMVA and base voltage. > Do you convert the impedances by yourself or are they already given in p.u? > > Regards, > Simon > Am 6/28/2011 10:05 PM, schrieb Fanjun Meng: >> Thanks a lot! >> >> Fanjun Meng >> >> >> >> On Tue, Jun 28, 2011 at 12:36 PM, Santiago Torres <[email protected]> >> wrote: >> Maybe the generation costs you are using for the opf are causing problems. >> Try to check that!. >> >> Regards, >> >> Santiago >> >> 2011/6/28 Fanjun Meng <[email protected]> >> Thank you very much for your suggestion! >> Actually I did check the simple power flow result with constraints, the >> voltages, line flows, generations are all satisfied. That's why I'm confused >> with this problem. Is it possible that the line impedences and system >> topology may cause matrix sigularity during OPF calculation iteration and >> fail to converge? >> >> Thanks a lot! >> >> Fanjun Meng >> >> >> >> >> On Tue, Jun 28, 2011 at 10:13 AM, Santiago Torres <[email protected]> >> wrote: >> The simple power flow has not constraints, so maybe with the settings you >> are using the power flow converges and has solution, however when you use >> the opf, some constraints can cause it does not converge. Check if the IEEE >> 123 node reported solution when using the simple power flow is complying the >> constraints (ie voltages, power generation, power flows). >> >> I hope this can help. >> >> Santiago Torres >> >> 2011/6/28 Fanjun Meng <[email protected]> >> Hello, >> >> I've been working on IEEE 123 nodes system and created a model for MatPower >> power flow. This model is basically a radial distribution system with a >> single generation at substation and works fine when I can use runpf(), and >> it returns similar result as shown IEEE 123 node system report. However, >> when I use the same model for runopf(), it shows >> >> >> Numerically Failed >> Did not converge in 4 iterations. >> Did not converge (0.10 seconds) >> >> The total generation is very different from total demand, and bus voltages >> are at strange values (e.g. 1.836p.u. at reference bus). Also, generation >> cost Lambda are extremely high (e.g. 17528752586.76 $/MWh @ bus 6). I have >> tried to add multiple DGs at different locations and change the system to a >> ring type system, but it didn't work out. Does anyone have any suggestions >> or experiences to this problem? Your help is highly appreciated! >> >> Have a good day! >> >> Fanjun Meng >> >> >> >> >> >> -- >> Dr.-Ing. Santiago Torres >> IEEE Senior Member >> >> Post-Doctoral Fellow >> School of Electrical and Computer Engineering >> University of Campinas, Campinas, SP, Brazil >> >> http://www.dsee.fee.unicamp.br/ >> >> Albert Einstein, 400 >> 13083-852, Campinas, SP, Brazil >> >> >> >> >> -- >> Dr.-Ing. Santiago Torres >> IEEE Senior Member >> >> Post-Doctoral Fellow >> School of Electrical and Computer Engineering >> University of Campinas, Campinas, SP, Brazil >> >> http://www.dsee.fee.unicamp.br/ >> >> Albert Einstein, 400 >> 13083-852, Campinas, SP, Brazil >> > >
