Chris,
Iterative methods in general (whether they are N-R, FD, G-S, etc.) are
prone to failure; you can sometimes mitigate this problem, but you can
never eliminate it 100%. It sounds like you may have hit one of those cases
where NR iteration fails and it's hard to find "the right seed". Our
com
Dear Jose and Ray,
thanks for your replies, I've tested another few things:
I deactivated the other two PV-buses, so there is only one reference bus,
many PQ-buses and the problematic PQ/PV-bus.
With the PQ (result is ok):
- Slack inserts: -60 Mvar
- Problematic bus: 0.118 Mvar, V=1.0335 pu
Wit
Sorry for the confusion, Ray: where I said, *"...solvable with the bus
running as PV, but unfeasible when the bus is running as PQ"*, I meant to
say:
"*a valid powerflow solution* with the bus running as PV, but an
*unstable* one when the bus is running as PQ"
(it is one of the multiple low
Thanks Jose. I’ve added that to the manual as you suggested.
I also agree with your suggestions for Chris. However, I’m curious about your
[*] note. In the situation you describe, it’s just that the Newton method will
diverge, correct? The original solution will still be a solution of the power
Interesting, I didn't know that enforcing Q-limits also affects generators
when their bus-type is set to PQ. Ray, I suggest documenting this behavior
in the manual, probably at the end of the last paragraph in Section 4.1.
Something to the effect of *"... Note also that this option affects
generat
Sorry, one mistake in my example: the BUS_TYPE in the second case should
obviously be 2 (PV), not 1.
--
Jose L. Marin
Grupo AIA
On Thu, Apr 28, 2016 at 11:48 PM, Jose Luis Marin
wrote:
>
> Looking at those records I think I may have misunderstood what you're
> doing. I thought you were conv
Looking at those records I think I may have misunderstood what you're
doing. I thought you were converting a given PQ bus (BUS_I=246) into PV,
but the generator record you're showing is attached to BUS_I=1 instead.
To be precise, I thought you were starting from (numbers made up for this
example)
Hi,
@ Jose L. Marin:
I used a generator in both cases, hence it should be the correct sign
(should result in the same I guess). Anyway P was very small, around
1e-6 MW.
I'm not sure if I've modelled something wrong: S_base is 100, my
generator is at bus 1 (at the end zeros(1,12)):
bus
Those are certainly some crazy Mvar injections! Just checking: are you
sure you reversed the signs of P properly when switching the type of that
bus from PQ (load) to PV (gen with neg real power), also taking care of
making the corresponding changes in the bus row and adding a new gen row?
If you
Ray's suggestion is an excellent idea. I'd like to add the following.
Suppose you start with "caseA", which solves ok. Now you make only one
change to obtain "caseB": you switch one particular PQ bus to PV type, by
carefully specifying its Vg as the voltage value you obtained in the
solution of
It sounds like the voltage at that bus may be very sensitive to the reactive
power injection. One thing you might try to get some idea of this is to change
that bus back to PQ with the reactive at the lower limit, then try running a
few cases with slightly perturbed values of the reactive power
Hi,
I'm using Matpower (v5.0b1, but the same holds for v5.1) for a 220 kV/110
kV/20 kV-grid quite a while. The grid has 1 reference bus (220 kV), 2
PV-buses (220 kV) and >100 PQ-buses (110 kV & 20 kV). So far calculating
the grid using runpf with Newton has never been a problem.
Now I've tried
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