We have a problem of the form ...
min f(x)
s.t. h(x) = 0, g(x) <= 0
xmin <= x <= xmax
It is not clear to me that it is necessary, or even useful, to
classify any of the variables as state variables. We simply describe
the dependency relationships among the variables via the equality
constraints. With nb buses and ng generators, we have 2*nb + 2*ng
variables and 2*nb + 1 equality constraints (power flow equations and
reference angle) limiting the degrees of freedom.
--
Ray Zimmerman
Senior Research Associate
428-B Phillips Hall, Cornell University, Ithaca, NY 14853
phone: (607) 255-9645
On Apr 29, 2008, at 2:59 PM, [email protected] wrote:
Thanks!
I think if we treat the generator real and reactive powers as
control variables,
then the bus voltage angles and magnitudes are state variables. Can
we treat
these four kinds of variables as control variable at the same time?
The bus
voltage angles and magnitudes are not dependent on generator real
and reative
power when the generator values change?
Quoting Ray Zimmerman <[email protected]>:
On Apr 29, 2008, at 11:43 AM, [email protected] wrote:
Dear Sir or Madam,
Thank you very much for your help!
And now I have some more questions about the control variables
in OPF.
1.) With the data of your cases,which variables could be
considered as
control variables?
2.) In your program, 'runopf',which variables are considered as
control
variables?
All voltage angles (except at the reference bus), all voltage
magnitudes and all generator real and reactive injections can be
considered as control variables. In the data, these appear in columns
8 and 9 of the bus matrix and columns 2 and 3 of the gen matrix.
3.) The data in 'Bus' matrix,the 5th and 6th columns,the shunt
conductance
and shunt susceptance, can they be treated as control variables? If
yes, how to
deal with these variables? What do these data exactly represent for?
No, MATPOWER does not have the ability to treat these as control
variables. They are for modeling things like fixed shunt capacitors.
4.) The transformer taps can be treated as control variables in
your data?
if yes,how to deal with them based on your data? And what do the
data of the
9th column in 'branch' matrix exactly mean?
Transformer taps are sometimes treated as controls in OPF programs,
but MATPOWER's formulation does not include this capability. The 9th
column of the branch matrix is the turns ratio of the transformer,
the
tau in the attached diagram of the branch model used by MATPOWER ...
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