See below.
From: Alexandra Kapetanaki
<[email protected]<mailto:[email protected]>>
Reply-To: MATPOWER discussion forum
<[email protected]<mailto:[email protected]>>
Date: Thu, 23 Jan 2014 21:19:27 +0000
To: MATPOWER discussion forum
<[email protected]<mailto:[email protected]>>
Subject: RE: error message
Dear Ray,
Thank you for your response.
I resolved the problem with the error message regarding dispatchable loads.
In addition, I would like to ask you and clarify some calculations that I make
by extracting data from Matpower.
1) I use the following commands to calculate the bus addmitance Ybus matrix and
impedance Zbus matrix:
[i2e,bus,gen,branch]=ext2int(bus,gen,branch);
[Ybus, Yf, Yt] = makeYbus(baseMVA, bus, branch);
Zbus=1./Ybus;
The './' operator in Matlab does a pointwise division, it does not compute the
inverse.
The values of the matrixes are in pu, isn't it?
2) After that I am interested in computing the shunt addmitance ysh of π
equivalent circuit of a line j->k in pu.
bs=mpc.branch(:,BR_B);
ysh=1./bs
Is that correct?
This is incorrect. Branch(:,BR_B) is the line charging susceptance. See section
3.2 of the manual.
3) Then I calculate the nodal voltages in pu
for f=1:24
Vf(f,1)=results.bus(f,VM)*exp(1j*results.bus(f,VA)*(pi/180));%*mpc.bus(f,10);
end
4) Then the nodal currents in pu
I=Ybus*Vf;
5) Finally, I calculate the P(in pu) through a line jk associated with nodal
currents.
Note that (4) is the nodal current vector, i.e., the current contributions
from transmission lines, shunt devices connected to each node. It is not a
vector of line currents. You can use the matrices Yf and Yt, output of the
makeYbus routine, to get the line currents. The routine makeYbus has info on
the matrices Yf and Yt.
For the computation of Preal value, the Sbase=100MVA is used for the whole
network?
Yes.
Thank you in advance for your support!
Cheers,
Alexandra
Alexandra Kapetanaki
PhD Student
Electrical Energy & Power Systems Group, School of Electrical & Electronic
Engineering
Ferranti Building (B18), The University of Manchester, M13 9PL, United Kingdom
Tel: +44 (0) 161 306 2263; Mobile: +44 (0) 7857 598179
________________________________
From:
[email protected]<mailto:[email protected]>
[[email protected]<mailto:[email protected]>]
on behalf of Ray Zimmerman [[email protected]<mailto:[email protected]>]
Sent: 23 January 2014 16:58
To: MATPOWER discussion forum
Subject: Re: error message
If you have a working dispatchable load (one that doesn’t give you the error
message you describe) and you are scaling both the active and reactive load
(PMIN and QMIN/QMAX) by multiplying by the same constant factor, you should not
see this error. If that is what you are doing and you are seeing an error,
please send me (off-list) a short script (the smallest example you can come up
with) that I can use to reproduce the error.
--
Ray Zimmerman
Senior Research Associate
B30 Warren Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645
On Jan 20, 2014, at 7:47 AM, Alexandra Kapetanaki
<[email protected]<mailto:[email protected]>>
wrote:
Dear Ray,
In addittion to my previous question, I would like to ask about the following
error message:
Error using makeAvl (line 83) makeAvl: For a dispatchable load, PG and QG must
be consistent with the power factor defined by PMIN and the Q limits.
I face this problem when I iteratively reduce the Load (both MW and MVAr) by
the same constant factor each time.
I use dispatchable loads.
How should I sort this out??
Kind Regards,
Alexandra
Alexandra Kapetanaki
PhD Student
Electrical Energy & Power Systems Group, School of Electrical & Electronic
Engineering
Ferranti Building (B18), The University of Manchester, M13 9PL, United Kingdom
Tel: +44 (0) 161 306 2263; Mobile: +44 (0) 7857 598179
