Dear Dr Zimmerman, I would like to ask you, where is it possible to find the source code of the matpower ACOPF equations? SInce you already mentioned that it is open to everyone! Thank you
________________________________ From: Ray Zimmerman <[email protected]> To: MATPOWER discussion forum <[email protected]> Sent: Tuesday, May 14, 2013 7:32 PM Subject: Re: branch modeling Yes. On May 14, 2013, at 12:55 AM, Petre Razusi <[email protected]> wrote: Thank you Prof. Zimmerman. Your explanations helped me. However, I still have another thing that is a little bit unclear. >I have some transformer parameters (in Ohms and Siemes) calculated using the >"to" side voltage. How do I convert them to p.u.? Do I use the same Zbase that >you suggested? > >Thank you for your help! > >Petre > > > > >2013/5/13 Ray Zimmerman <[email protected]> > >Since the branch impedances are on the "to" side of the branch, you are >correct that you would use the voltage base from the "to" bus. >> >>The formula isn't really a MATPOWER question, so you should be able to find >>the answer in a good power systems textbook, however it is very >>straightforward to derive yourself. Essentially we want to find the impedance >>base (Zbase) in terms of the power and voltage bases (Sbase and Vbase). >> >>Start with some definitions ... >> >>(1) V = Vpu * Vbase >>(2) S = Spu * Sbase >>(3) Z = Zpu * Zbase >> >>Then some simple relationships ... >> >>(4) V = I * Z >>(5) S = V * conj(I) >> >>Solving (4) for I and substituting in (5), then solving for Z, gives ... >> >>(6) Z = |V|^2 / conj(S) >> >>And we know the p.u. quantities have the same relationships … >> >>(7) Zpu = |Vpu|^2 / conj(Spu) >> >>Substituting (1)-(3) and then (7) into (6) and rearranging, gives … >> >>Zbase = Vbase^2 / Sable >> >>Hope this helps, >> >>-- >>Ray Zimmerman >>Senior Research Associate >>419A Warren Hall, Cornell University, Ithaca, NY 14853 >>phone: (607) 255-9645 >> >> >> >> >> >>On May 13, 2013, at 3:44 AM, Petre Razusi <[email protected]> wrote: >> >>> Dear all, >>> >>> I have some things I don't quite understand regarding the modeling of >>> branches and the pu system. >>> If I'm not wrong, to transform the R,X and B parameters to pu one needs a >>> base impedance. Since the model used for the branch is a complex one, >>> dealing with both transformers and lines, I presume that this impedance is >>> calculated using the "to" bus voltage. Am I right? And if so, could you >>> tell me what is the formula used to compute the base impedance? >>> >>> Thanks, >>> >>> Petre >> >> >> >> > > > >
