Hi Jun Wu,
Thanks for pointing this out. You have, indeed, found a bug that was
introduced in 3.0b4 and is present it all subsequent versions. It
will be fixed for the next release.
Specifically, if any generator has QMIN equal to QMAX, the power flow
solution will have Qg incorrectly set to zero for that generator.
This does not affect the OPF.
In response to your question regarding Vg, it should be the desired
voltage set-point for that generator, and in the absence of better
information, 1 p.u. is a reasonable default.
Ray
On Apr 27, 2007, at 11:07 PM, Jun Wu wrote:
By your instruction, the problem is smoothed. Thank you very much!
But I found an interesting thing, the PF result of 3.0b3 is
slightly different from that of 3.0.0 or 3.1b2. The attachment is
my test system and results of different versions. The only
difference is the Q of bus 1. I set the Qmax and Qmin of bus 1 to
zero so that I think the Q calculated should also be zero. But it
is not zero by using 3.0b3 while it is zero by using 3.0.0 or 3.1b2.
By the way, I want to ask another question. If the initial values
of Vg should be 1 or other?
2007/4/27, Ray Zimmerman <[email protected]>:
When upgrading you should completely remove all files from the
previous version from your Matlab path. Then add all of the files
from your new version to your Matlab path.
If 'isload' is not defined it means you do not have the new version
installed correctly ... isload.m is one of the files in the new
version and should be in your path.
--
Ray Zimmerman
Senior Research Associate
428-B Phillips Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645
On Apr 27, 2007, at 1:27 AM, Jun Wu wrote:
Dear Ray Zimmerman,
Is the higher version compatible with the lower version well? I
found some problems. I used 3.0b3 before, which is lack of the new
feature you've referred. So I copy all files of 3.1b2 to replace
them. But the same program can not work with the error--Undefined
function or method 'isload' for input arguments of type 'double'.
I don't know how update it simply
Yours sincerely,
Wu Jun
Unit: State Key Lab. of Power Systems,
Dep. of Electrical Engineering,
Tsinghua University, P.R. China.
Email: [email protected]
2007-04-27
2007/4/27, Ray Zimmerman <[email protected]>:
On Apr 26, 2007, at 11:02 AM, Jun Wu wrote:
Thanks for your attention and suggestion. I think reading the
manual more will help me. But I never saw it before. Is this the
latest feature for version 3.1b2? Does 3.0b3 has this setting?
This feature was added in 3.0b4 and was included in the final
3.0.0 release (3.0b4 was a beta version). It is also included in
the beta releases for 3.1.
By the way, what do below settings mean?
38 - OUT_ALL_LIM, -1 control constraint info output
[ -1 - individual flags control what constraint info
prints]
[ 0 - no constraint info (overrides individual
flags) ]
[ 1 - binding constraint info (overrides individual
flags)]
[ 2 - all constraint info (overrides individual
flags) ]
39 - OUT_V_LIM, 1 control output of voltage
limit info
[ 0 - don't
print ]
[ 1 - print binding constraints
only ]
[ 2 - print all
constraints ]
[ (same options for OUT_LINE_LIM, OUT_PG_LIM,
OUT_QG_LIM) ]
40 - OUT_LINE_LIM, 1 control output of line limit
info
41 - OUT_PG_LIM, 1 control output of gen P limit
info
42 - OUT_QG_LIM, 1 control output of gen Q limit
info
These options control the constraint sections of the output for
the OPF solver only.
Ray
2007/4/26, Ray Zimmerman <[email protected]>:
By default, the power flow solver does not take into account the
voltage or reactive power limits. However [1] ...
For the AC power flow solvers, if the ENFORCE_Q_LIMS option is
set to true (default is false), then if any generator reactive
power limit is violated after running the AC power flow, the
corresponding bus is con- verted to a PQ bus, with the reactive
output set to the limit, and the case is re-run. The voltage
magnitude at the bus will deviate from the specified value in
order to satisfy the reactive power limit. If the generator at
the reference bus is reaches a reactive power limit and the bus
is converted to a PQ bus, the first re- maining PV bus will be
used as the slack bus for the next iteration. This may result in
the real power out- put at this generator being slightly off from
the specified values.
[1] Taken from p. 10 of the User's Manual (http://
www.pserc.cornell.edu/matpower/manual.pdf ).
--
Ray Zimmerman
Senior Research Associate
428-B Phillips Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645
On Apr 26, 2007, at 5:23 AM, Wu Jun wrote:
Hi all,
From the case30.m in Matpower, Vmax and Vmin for buses are
listed, also the Qmax and Qmin for generators. I want to know
how they work during the process of calculating the power flow.
If one of them are violated, how does Matpower treat it? Does
Matpower keep the original outputs or change the calculation
condition automatically then put out a result without breaking
any limit?
--------------
Yours sincerely,
Wu Jun
Unit: State Key Lab. of Power Systems,
Dep. of Electrical Engineering,
Tsinghua University, P.R. China.
Email: [email protected]
2007-04-26
<PF of 3.0b3.txt>
<PF2 of 3.0.0 and 3.1b2.txt>
<testcase30.m>
