I tried using the feasible solution as initial conditions, but unfortunately it didn't converge, which is really wired. I'm guessing the system topology and parameters is causing trouble, and I may want try to scale up the generation and demand in the system and decrease the step size in order to better search for a feasible solution.
Thank you very much! *Fanjun Meng Electrical Engineering Missouri University of Science & Technology [email protected] <[email protected]>* On Thu, Jul 7, 2011 at 10:44 AM, Ray Zimmerman <[email protected]> wrote: > Could you try using the feasible power flow solution (from runpf) as the > starting point for runopf and try using MINOPF as the solver? > > pf_soln = runpf('case123'); > opt = mpoption('OPF_ALG', 500); > r = runopf(pf_soln, opt); > > -- > Ray Zimmerman > Senior Research Associate > 211 Warren Hall, Cornell University, Ithaca, NY 14853 > phone: (607) 255-9645 > > > > On Jul 6, 2011, at 10:42 PM, Fanjun Meng wrote: > > Dear Dr. Zimmerman, > > Thanks for your suggestion. I've tried different solvers including PDIPM, > SCIPM, and TRALM, etc. All of these solvers still cannot converge while > solving the IEEE 123 nodes distribution system for an OPF solution. So I'm > wondering if it is diverging because the 123 nodes is a distribution system > with a lot end branches not in a loop. Also I notice the lines in the 123 > nodes have very similar impedence (which is typical in a distribution > system), will this cause singular or bad scaled matrix while solving for > OPF? > > Thanks for your time! > > > *Fanjun Meng > * > > > > On Thu, Jun 30, 2011 at 8:07 AM, Ray Zimmerman <[email protected]> wrote: > >> 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] <[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 >>>> >>> >>> >>> >> >> > >
