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]
>>
>>
>>
>> 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
>>>
>>
>>
>
>
