*Dear Dr Zimmerman, Shiyang, Li and Arash*
Thank you for your reply to my problem. Dr Zimmerman has said that I need to use OPF *instead of PF* for branch thermal constraints. The problem is that I am using another optimization method connected to Matpower and this optimization program only needs to use V,P,Q and delta values from the power flow calculations. In my optimization program, I am trying to minimize P loss and other things so if I use OPF, my final results would be affected and they are not purely from my optimization method. I also tried to code the thermal limit for PF myself but I haven’t been able to. *Would you please help me in coding the thermal constraints?* Regards Iman 2012/1/13 新浪VIP <[email protected]> > Hi Iman， > 1, Even your object is to study the system near static limit, keeping all > generation of PV buses is usually not reasonable, because this scenario may > never occur. For this sake, when we calculate load margin for example, we > normally increase P generation with loads. > > 2, Power is always conserved on static state. Without PV generation > increasing > , the slack bus has to compensate all the deficit, 236.55 MW here. > > 3, Like what Dr Ray said, if you want to involve thermal limits of > branches, you may either use OPF solver, or code you own function to adjust > PV generations. > > Shiyang Li > > 发自我的 iPhone > > 在 2012-1-12，21:44，iman <[email protected]> 写道： > > Dear Shiyang, Li > > Thanks for taking time answering. > > I didn’t increase any generations in the PV buses because my objective for > increasing the load is pushing the system to the instability margin (like > voltage drop in buses). > > I agree with you that network loss doesn’t seem a real number as well as > other numbers. > > In the case30.m (base case) after running pf I have: > > *Total generation capacity =335 MW* > > *On-line capacity =335 MW* > > *Continued Gens (actual generation)=191.6 MW* > > *Load = 189.2 MW* > > *Losses=2.44 MW* > > * * > > *Branch 1-2 =10.89 MW* > > *Branch 1-3=15.08 MW* > > ****Now I multiply Pd (demanded power)by 2 to make the whole consumption > twice, I have*** > > *Total generation capacity =815 MW* > > *On-line capacity =815 MW* > > *Continued Gens (actual generation)=402.2 MW* > > *Load = 378 MW* > > *Losses=23.82 MW* > > * * > > *Branch 1-2 =154.81 MW* > > *Branch 1-3=81.08 MW* > > * * > > * * > > Having said the above in brief: > > 1-In Bus 1 (Slack) we have 236.55 MW injection power .Where does this > added amount come from? > > 2-What if I want to fix branch 1-2 limit to 100 MW (or 100 MVA)? What > should I do? > > > > Thank you for your attention and time > > Wish you the best. > > Iman > > > On Wed, Jan 11, 2012 at 7:45 PM, 李诗旸 <[email protected]> wrote: > >> Dear Iman,**** >> >> With the load increasing, have you increase the generation from PV buses? >> I don’t think the network loss could usually increase to nearly 10 times >> even at static limit. You may double the Pg on PV buses with the load. >> Then, if you still want to impose the branch thermal limits, you have to >> code the function to adjust the Pg for PV buses based on participant >> factors (branch flow sensitivity w.r.t. generation) or others.**** >> >> ** ** >> >> Shiyang, Li**** >> >> ** ** >> >> ** ** >> >> *发件人:* [email protected] [mailto: >> [email protected]] *代表 *iman >> *发送时间:* 2012年1月12日 0:57 >> *收件人:* [email protected] >> *主题:* limits on the branches**** >> >> ** ** >> >> Dear all,**** >> >> ** ** >> >> I want to use power flow (PF) for the load increase studies. I picked 30 >> bus system with Pg=23.54 MW for the slack bus. Running the power flow with >> the base loads ,I get 25.97 MW which is quite close to 23.54.**** >> >> Now I want to increase all of the loads 2 times. Running pf I get 236.55 >> MW for the slack bus .**** >> >> I think in practice thermal line limits doesn’t allow this amount of >> power dragging from slack bus.**** >> >> I want to make my problem practical by imposing thermal limits on the >> branches .How can I do that?**** >> >> ** ** >> >> Thank you in advance for your patience **** >> >> I look forward to hear from you guys**** >> >> Iman**** >> > > > > -- > Best regards > Iman > > -- Best regards Iman
