Dear Prof. Ray Zimmerman,
Thank you very much for your help. I have implemented your suggestion of relaxing constraints over conventional power plants and got successful convergence on both model. While doing so in 2# model I kept minimum value of generation Pmin=0, and instead of using single slack generator output to supply system losses I increased all conventional generators output by 2% means Pmax=(Original Pmax)*1.02. So that losses will be contributed by all generators. But I want to clarify some doubts. 1) My *Objective Function Value = -243875269.94 $/hr* is highly negative after convergence, that I don’t understand why it’s highly negative. After *mpc=load2disp(mycase)* I checked mpc.gencost matrix. In my case conventional generators variable cost function is linear e.g. [2 0 0 3 0 10.91 0] and renewable generators and cross border generators cost is zero e.g. [2 0 0 3 0 0 0] and for dispatchable loads I set linear cost function [2 0 0 3 0 5000 0]. Am I using correct values in mpc.gencost matrix? Or I have to use for conventional power plants = [2 0 0 3 0 0 0] and for both renewables and dispatchable loads= [2 0 0 3 0 5000 0] ? Both approach gives negative objective function value. 2) When I perform successfully *res=runopf(mpc) *all curtailments on renewable / loads / redispatch of conventional power plants will be seen in *res.gen(:,2)* column (second column of res.gen matrix) right? Thank you very much for your time. Regards Mirish Thakur On Mon, Nov 30, 2015 at 5:54 PM, Ray Zimmerman <r...@cornell.edu> wrote: > Hi Mirish, > > There is no way to see the load or renewable curtailment until you get a > converging OPF. It is possible that you will also have to redispatch the > conventional generators in order to get a feasible solution. I would > suggest that you combine your option #2 with curtailable loads, relax the > active power dispatch constraints on the conventional generators (to their > normal limits) and assign piecewise linear costs to those generators with > negative or zero marginal cost up to Pg and large positive marginal cost > above Pg. This will attempt to minimize deviations from the original > dispatch pattern, hopefully moving only those generators necessary to > relieve the line overloads. > > Ray > > On Nov 29, 2015, at 7:31 PM, Mirish Thakur <mirishtha...@gmail.com> wrote: > > Hello friends, > > > I’m working on (1000 bus system) reactive power dispatch problem. I have > modeled grid into matpower case file and I’m getting the results of > *runpf*. But when I use *ACOPF* it fails to converge. > > I have modeled grid into two methods > > 1) I used all renewable energy sources generation, pump storage power > plant and cross border energy transfer as negative load. And all > conventional power plants as generators. Dispatch of conventional > generators is equal to residual load so demand is equal to generation. > Further I have increased limits of slack generator to supply system losses > and kept rest of generators dispatch constant by *Pmax=Pmin=Pg*. Also > *RATE_A* limits should be unchanged. (Necessary condition for project). > > > 2) In other way all renewable energy sources generation, pump storage > power plant and cross border energy transfer are modeled as generators and > put next to all conventional power plants. And in *gencost *matrix I used > zero variable cost for renewable generation. Slack generator and rest of > the conditions are set as it is in first approach. > > > My question is in both modeling I got *runpf* successfully converged but > I’m not getting convergence for *ACOPF*. So, I checked branch limits on > some branches which I found overloaded by analyzing results of *res= > runpf (mymodel)*. To avoid such overloading I want to change > distribution pattern of load which might be cause of overloading of > branches. I tried *load2disp* function to get curtailment on load but > every time I got failure in convergence in *runopf*. I went through below > mentioned discussions- > > https://www.mail-archive.com/matpower-l%40cornell.edu/msg04423.html > > https://www.mail-archive.com/matpower-l%40cornell.edu/msg00790.html > > https://www.mail-archive.com/matpower-l%40cornell.edu/msg01203.html > > Is there any way to see curtailment on load or negative generation (renewable > generation/ cross border transfer of energy) so that I can redistribute that > load /negative generation on other bus bars so that I can avoid overloading > of branches and get successful convergence? Many thanks. > > Regards > > Mirish Thakur > > KIT University > > >
