I tried (unsuccessfully) to solve your dispatchable load case with several
different solvers, so I think it might be infeasible, but I’m not sure. I
didn’t have the time to try to figure it out.
However, I was able to convert your original loads to dispatchable loads using
the load2disp() function and then I was able to solve it with MIPS, but only
after turning on the step-control mechanism.
mpc = loadcase('Workingmodel1');
mpc.gen(59,21) = 0; % expand to full number of columns
mpc.gencost = ones(59, 1) * [2 0 0 2 10 0]; % all gens have $10/MW costs
mpc2 = load2disp(mpc);
mpopt = mpoption('out.bus', 0, 'out.branch', 0, 'out.lim.all', 0);
mpopt = mpoption(mpopt, 'opf.ac.solver', 'MIPS', 'mips.step_control', 1);
r = runopf(mpc2, mpopt)
Hope this helps,
Ray
--
Ray Zimmerman
Senior Research Associate
B30 Warren Hall, Cornell University, Ithaca, NY 14853 USA
phone: (607) 255-9645
On Jul 17, 2014, at 5:12 AM, HEGGIE Alastair <[email protected]> wrote:
>
> Dear Professor Zimmerman and list subscribers,
>
> I am attempting to use MATPOWER to analyse optimal load shedding in a model
> of the Nigerian power system. Would anyone be able to help me understand why
> my optimal load shedding is not working? I have spend a lot of time trying to
> get this to work myself but I am not sure what else to do. I would be very
> grateful for any assistance. Please do ignore if this is not an appropriate
> question for this list.
>
> The attached model, Workingmodel1.m is the case file automatically converted
> from a PSSE .raw file.
>
> For each load buss in the following form:
>
> BUS I BUS TYPE PD QD GS BS BUS AREA
> VM VA BASE KV ZONE VMAX VMIN
> 13004 1 155.548 75.335 0.000 0.000 1
> 0.9586100 -3.6472000 330.00 15 1.10 0.90;
>
> I have set PD and QD to zero:
>
> 13004 1 0 0 0 0 1 0.95861 -3.6472 330
> 15 1.1 0.90;
>
> I have then added a corresponding generator with PMAX and QMAX = 0 and PMIN
> and QMIN equal to the negative real and reactive demand at the bus. Following
> advice in another thread I set PG = PMIN and QG = QMIN. I am not sure what
> MBASE should be so I set this to zero.
>
> GEN BUS PG QG QMAX QMIN VG MBASE GEN STATUS
> PMAX PMIN
> 13004 -155.548 -75.335 0 -75.335 1 0 1 0
> -155.548 ;
>
> I have given each dispatchable load a peicewise linear cost with a kink in
> the gradient at half the real power output so that the costs have the
> following form:
>
> MODEL STARTUP SHUTDOWN NCOST COST
> 1 0 0 3 0 0 -77.774 -750000 -155.548
> -1000000
>
> It was suggested in another thread that zero cost generators might confuse
> some solvers so I gave each generator a small positive cost of the following
> form
>
> MODEL STARTUP SHUTDOWN NCOST COST
> 2 1 0 6 0 0 0 0 1 1
>
> The resulting model is attached at Workingmodel1_loadshedding.m. This model
> reports a numerical failure when I try to run the opf.
>
> I am not sure whether there is something wrong with my base model or whether
> my dispatchable load conversion is in error. I have tried working with some
> of the simpler cases provided with MATPOWER (see for example the attached
> case9h.m and case14b.m ) and have not been able to get load shedding working
> with these either.
>
> Thank you for any assistance,
>
> Alastair Heggie
> --
> The University of Edinburgh is a charitable body, registered in
> Scotland, with registration number SC005336.
>
>
> <case9h.m><case14b.m><Workingmodel1.m><Workingmodel1_loadshedding.m>
