Jubeyer Rahman wrote:
Hi,
I have several questions regarding the AC power flow in matpower.
a. I would like to know whether the AC Power Flow command ('runpf')
,when called, does it have any constraint to constrain the transformer
power rating violation which is related to the real and reactive power
flows into the transformers both at origin bus and destination bus?
No, it doesn't; the traditional formulation of the power flow does not
include this feature (it would not be what is normally calle a "power
flow"). MATPOWER does include the option to try to remain within
reactive generation limits, though. This requires changing the type of
the conflicting generator's bus from "PV" to "PQ".
b. How to incorporate transformer's magnetizing conductance in the
power flow equations? Or does matpower already takes care of it? ( I
didn't see it in the matpower AC PF formulation)
The magnetizing susceptance is not included in the general branch model
that MATPOWER employs. At the transmission level, neither the core loss
conductance nor the magnetizing susceptance are usually modeled. If you
assume that either the "from" side voltage or the "to" side voltage is
what is actually present at the terminals of these two elements, then
they could be added as shunt elements in the corresponding bus. Just
not in the branch specification.
c.Is there any way to change the power balance equations at buses? Any
matpower example or reference to the example will be greatly appreciated.
Ray answered this.
d. I have observed after running a power flow, one generator's real
power has gone below its minimum, this happens when I took one branch
out to simulate a branch contingency event. Do you know why this is
happening? I mean, this is violating the Pmax and Pmin constraints?
That generator could only be the slack generator, since all other
generator's active power output remains fixed in a traditional power
flow. The problem seems to be in the specification of the power output
for non-slack generators. The slack generator must adjust the overall
active power balance, that's what it is for. This is one of the
underlying assumptions in the formulation of a traditional power flow.
Regards,
Jubeyer
carlos.
