Hi Uriel,
Is there documentation (apologies if I missed it) that explain how the power
flow handles input data? For example, from the case you just got working for
me (attached):
1) The mpc.bus field “Vm” appears to just be treated as the initial guess
for the bus voltage magnitude.
2) The mpc.bus field “Va” actually fixes the bus angle permanently.
If you change Va to, say 10°, then the load flow result will be:
================================================================================
| Bus Data |
================================================================================
Bus Voltage Generation Load
# Mag(pu) Ang(deg) P (MW) Q (MVAr) P (MW) Q (MVAr)
----- ------- -------- -------- -------- -------- --------
1 1.154 10.000* -149.60 -39.69 - -
2 1.174 13.313 149.60 49.10 - -
-------- -------- -------- --------
Total: -0.00 9.41 0.00 0.00
That is a perfectly good result of course. I am playing around to see what
values matter and what don’t – but I’m wondering if there is a document that
explains things like “this is an initial guess” or “this setting fixes this
angle” etc.
Best regards,
Russ
From: [email protected]
[mailto:[email protected]] On Behalf Of Uriel Fernando
Sandoval Pérez
Sent: Tuesday, December 8, 2020 11:07 PM
To: MATPOWER discussion forum
Subject: Re: infinite bus, 1 branch/1 gen
Hi Russ,
Attached is the file with some modifications. I obtained the same result you
got manually.
================================================================================
| System Summary |
================================================================================
How many? How much? P (MW) Q (MVAr)
--------------------- ------------------- ------------- -----------------
Buses 2 Total Gen Capacity 0.0 49.1 to 49.1
Generators 2 On-line Capacity 0.0 49.1 to 49.1
Committed Gens 2 Generation (actual) -0.0 9.4
Loads 0 Load 0.0 0.0
Fixed 0 Fixed 0.0 0.0
Dispatchable 0 Dispatchable -0.0 of -0.0 -0.0
Shunts 0 Shunt (inj) -0.0 0.0
Branches 1 Losses (I^2 * Z) 0.00 9.41
Transformers 0 Branch Charging (inj) - 0.0
Inter-ties 0 Total Inter-tie Flow 0.0 0.0
Areas 1
Minimum Maximum
------------------------- --------------------------------
Voltage Magnitude 1.154 p.u. @ bus 1 1.174 p.u. @ bus 2
Voltage Angle 0.00 deg @ bus 1 3.31 deg @ bus 2
P Losses (I^2*R) - 0.00 MW @ line 1-2
Q Losses (I^2*X) - 9.41 MVAr @ line 1-2
================================================================================
| Bus Data |
================================================================================
Bus Voltage Generation Load
# Mag(pu) Ang(deg) P (MW) Q (MVAr) P (MW) Q (MVAr)
----- ------- -------- -------- -------- -------- --------
1 1.154 0.000* -149.60 -39.69 - -
2 1.174 3.313 149.60 49.10 - -
-------- -------- -------- --------
Total: -0.00 9.41 0.00 0.00
================================================================================
| Branch Data |
================================================================================
Brnch From To From Bus Injection To Bus Injection Loss (I^2 * Z)
# Bus Bus P (MW) Q (MVAr) P (MW) Q (MVAr) P (MW) Q (MVAr)
----- ----- ----- -------- -------- -------- -------- -------- --------
1 1 2 -149.60 -39.69 149.60 49.10 0.000 9.41
-------- --------
Total: 0.000 9.41
Best,
Uriel
El mar, 8 de dic. de 2020 a la(s) 19:59, Russ Patterson ([email protected])
escribió:
Hi Uriel,
I made the changes you suggested and I’m getting this “out of bound” error:
>> runpf('example1')
error: pv(1): out of bound 0 (dimensions are 0x1)
error: called from
bustypes at line 43 column 13
runpf at line 114 column 19
thank you,
russ
From: [email protected]
[mailto:[email protected]] On Behalf Of Uriel Fernando
Sandoval Pérez
Sent: Tuesday, December 8, 2020 7:18 PM
To: MATPOWER discussion forum
Subject: Re: infinite bus, 1 branch/1 gen
Hi,
It seems you are modelling de active/reactive power injections as a negative
load. But,
then you also define a generator with P=149.6 and Q=49.104. You should delete
de load ( set to zero Pd and Qd), fix the active power of the generator and set
Qmax=Qmin=49.104
Hope this helps.
El mar., 8 de diciembre de 2020 16:02, Russ Patterson <[email protected]>
escribió:
Hi,
I have a simple problem as shown below. The upper bus is the infinite, slack
bus. For the specified P & Q, I want to solve for VX. Per my hand
calculations (iterations) the result will be VX=1.174pu @-3.3°.
Now, I am trying to model this in a simple load flow as my first ever attempt
to use MATPOWER (attached, which fails miserably).
I have the manual and understand all of the bus, generator, and branch data.
What I don’t know is – what can be left out in solving this simple problem?
The machine is rated 16kV, 176MVA but I’d prefer to leave that out and just
work all in per unit (including data entry) if possible.
Thanks,
Russ
_____
Russell W. Patterson, P.E.
Chair – IEEE PSRC (http://pes-psrc.org)
Office: 423-702-9981
function mpc = example1
%Example 1
% Bus 1 is infinite and is 1.154 pu and zero degrees
% Bus 2 has a 176MVA generator, P=0.85pu and Q=0.279pu both flowing into bus 2
% Impedance between bus 1 & 2 is j0.0921 pu
%
\\%% MATPOWER Case Format : Version 2
mpc.version = '2';
\\%%----- Power Flow Data -----\\%%
\\%% system MVA base
mpc.baseMVA = 176;
\\%% bus data
% bus_i type Pd Qd Gs Bs area Vm Va
baseKV zone Vmax Vmin
mpc.bus = [
1 3 0 0 0 0 1 1.154 0 16 1 1.154 1.154;
2 1 0 0 0 0 1 1 0 16 1 1 1;
];
\\%% generator data
% bus Pg Qg Qmax Qmin Vg mBase status Pmax
Pmin Pc1 Pc2 Qc1min Qc1max Qc2min Qc2max ramp_agc ramp_10
ramp_30 ramp_q apf
mpc.gen = [
1 0 0 0 0 1.154 100 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0;
2 149.6 49.104 49.104 49.104 1 100 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0;
];
\\%% branch data
% fbus tbus r x b rateA rateB rateC ratio
angle status angmin angmax
mpc.branch = [
1 2 0 .0921 0 0 0 0 0 0 1 10 -10;
];
