Hello Asma, I gave your case a quick look and I found several problems with the file format (many extraneous lines in several places). Anyway, I was courious and I found that I could edit it by hand quickly because it's actually a rather simple and repetitive topology structure. I'm attaching my fixed file, have a look at it (I also converted it to MATPOWER version 2). The second version contains an additional fix that I guessed (bus 1002 connecting to bus 3001, instead of 1001). By the way, you can quickly visualize the topology with this handy tool: http://immersive.erc.monash.edu.au/stac/
So it's a *very* radial case, with no loads, only (wind) generators, and
the swing acting as the "sink" for all of the wind-farm power, as it is the
connection point to the grid.
>From the point of view of powerflow, your case has two kind of problems:
1. The main one is that this network just cannot "evacuate" all that
power. The case is infeasible, as you can see by running a CPF.
2. A smaller problem is that all generators are running in PQ mode, with
Q=0 (power factor 1.0), which means that you won't have enough "reactive
support" to maintain voltage levels for such long radial sections.
Allowing the generators to inject at least some Mvars will let you transfer
a bit more power from the wind farm. See the attached test script. These
are the results I get (for caseborselle_fixed2):
- Operating gens at cos_phi=1.0 ==> max_lambda = 0.546875, mean
voltage = 0.802666
- Operating gens at cos_phi=0.95 ==> max_lambda = 0.807189, mean
voltage = 0.986915
- Operating gens at cos_phi=0.90 ==> max_lambda = 0.968138, mean voltage
= 1.104592
Hope it helps,
--
Jose L. Marin
Grupo AIA
2018-05-18 18:43 GMT+02:00 Asma DABBABI <asma.dabb...@etu.univ-nantes.fr>:
> Hello Jose,
> Thank you for rapid response, i'm quite in a rush to finish this study
> case for my thesis research.
>
> - i have a radial topology of wind turbines ( 100 wind turbines with 8 MW
> each) like i said i represent all my turbines nodes like a PQ node
> with P=8Mw et Q=0MVAR. and i have 3 AC offshores plateformes (ie 3
> transformers ) related to my wind farm (each transformer is related to one
> cluster in my wind farm) after that i have a long transmission line (
> distance about 60km) and finally i have a terrestrial network which is
> composed of one final transformer and the output node of the transformer
> is my slack bus ( my only generator).
>
> I put you my case file so you can more understand what i mean.
>
> from what I understood from your answer is that I have to add PV nodes and
> i have to add also Q for each turbine ?
>
> thank you again and i hope you can help me.
>
>
> Best regards
>
>
> > Hello Asma,
> >
> > Your description is not very clear, so let me ask you a couple of things
> > first:
> >
> > - You seem to be saying that your generators should have P=8 MW.
> > That's
> > fine, but then you total load should be balanced according to that (is
> > it?). Otherwise the imbalance, which has to be picked up by the slack
> > bus,
> > could render the case infeasible.
> > - You also seem to be saying that all your generators are PQ type. A
> > case with no PV buses is quite prone to numerical ill-conditioning
> > (unless
> > the total number of buses is low). Worse yet, if all gens have Q=0
> > then
> > all reactive power will have to be provided by the slack, and then
> > voltages
> > will quickly drop as you move away from the slack bus. And if the
> > network
> > topology is dominantly radial, things are even worse yet.
> >
> > Maybe we can help you faster if you could share your case file here.
> >
> > --
> > Jose L. Marin
> > Grupo AIA
> >
> >
> >
> > 2018-05-18 17:31 GMT+02:00 Asma DABBABI <asma.dabb...@etu.univ-nantes.fr
> >:
> >
> >> the library Matpower works perfectly with small wind farms (30 wind
> >> turbines with
> >> 3 mw each, the turbines are represented as PQnode with P=3MW and Q=0MVAR
> >> and i have one slack bus in the terrestrial network)
> >> but when I tried to make an example of a larger farm such as Borsselle
> >> Park (100 wind turbines of 8 mw each) I had a divergence of the system.
> >>
> >> "Newton's method power flow did not converge in 10 iterations ",
> >> I looked on the internet and I found that in this case we have to do a
> >> continuation power flow that gradually increases the loading/generation
> >> like this:
> >>
> >> {define_constants;
> >> mpcbase = loadcase ('casefile');
> >> mpcbase.bus (:, PD) = 0;
> >> mpcbase.bus (:, QD) = 0;
> >> mpcbase.gen (:, PG) = 0;
> >> mpctarget = loadcase ('casefile');
> >> results = runcpf (mpcbase, mpctarget);
> >> results.cpf.max_lam}
> >>
> >> If the resulting value of results is greater than 1, it indicates that
> >> the
> >> load for the box is greater than that of the loading and unloading
> >> system
> >> at least by a factor of results.cpf.max_lam to get a convergent power
> >> flow
> >> solution.
> >> I tried this and actually I found that it shows that results.cpf.max_lam
> >> is less than 1 so i must reduce the loads to 1.35 mw for each turbine.
> >> in my case i don't need to reduce the loads, i must found the losses of
> >> the network with 8mw for each turbine.
> >> I've tried many solutions that i found in matpower page but until now I
> >> have not found the right solution to calculate with 8 mw.
> >>
> >> So can you help me please on that, I 'll be so grateful if you answer
> >> me.
> >>
> >> Best regards,
> >>
> >>
> >>
> >>
> >
>
caseborselle_fixed.m
Description: Binary data
caseborselle_fixed2.m
Description: Binary data
test_caseborselle.m
Description: Binary data
