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�D <[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 >
