You may also want to check out the MATPOWER Tech Note on "AC Power Flows,
Generalized OPF Costs and their Derivatives using Complex Matrix Notation
<http://www.pserc.cornell.edu/matpower/TN2-OPF-Derivatives.pdf>” listed on the
MATPOWER web page.
Ray
> On Nov 20, 2015, at 11:16 AM, ALI ZAZOU Abdelkrim
> <[email protected]> wrote:
>
> Sorry i get it,
>
> abs(a*exp(x))=a
> so
> a*exp(x)/abs(a*exp(x))=exp(x)
>
> sorry for my mistake
>
> Thank you very much
> Abdelkrim
>
> Le 20/11/2015 11:59, ALI ZAZOU Abdelkrim a écrit :
>> Thank you very much for your explainations and advices.
>> So to understand how matpower operate i looked at "MATPOWER:
>> Steady-State Operations, Planning, and Analysis Tools for Power
>> Systems Research and Education" and the calcultion done in matlab but
>> i'm stuck with something.
>> In dSbus_dV.m where it's supposed to calculate the partial derivative
>> of the complex bus power injection, to proceed at one iteration of the
>> newton's method, i can't understand how you introduce Vm and Va in
>> Sbus expression.
>> i supposed that you used the expression:
>> U=Vm*exp(j*Va)
>> So logically:
>> dV/dVm=exp(jVa)
>> but what you explained is:
>> % Partials of V & Ibus w.r.t. voltage magnitudes
>> % dV/dVm = diag(V./abs(V))
>> % dI/dVm = Ybus * dV/dVm = Ybus * diag(V./abs(V))
>> and
>> dV/DVa=j*Vm*exp(jVa)<---- this one seems ok
>> % Partials of V & Ibus w.r.t. voltage angles
>> % dV/dVa = j * diag(V)
>> % dI/dVa = Ybus * dV/dVa = Ybus * j * diag(V)
>> Can you explained to me so how you get dV/dVm ???
>> Thank you very much for your reactivity
>> Abdelkrim
>> Le 19/11/2015 00:15, Carleton Coffrin a écrit :
>>> Hi Abdelkrim,
>>> I would recommend you have a look at the paper,
>>> Baran, M.E.; Wu, F.F., "Optimal sizing of capacitors placed on a
>>> radial distribution system," in Power Delivery, IEEE Transactions on ,
>>> vol.4, no.1, pp.735-743, Jan 1989
>>> It has a nice mathematical formulation of how voltage drops in a
>>> radial system, based on the power flow on the lines.
>>> Cheers,
>>> -Carleton
>>>> On Nov 19, 2015, at 7:15 AM, Ray Zimmerman <[email protected]> wrote:
>>>> In general, the voltage tends to drop as you get further from the source,
>>>> if loads are evenly distributed and line parameters are similar. In your
>>>> example, however, you have a much larger load at bus 9 than at bus 8, and
>>>> in particular, there is a large reactive load at 9, pulling down the
>>>> voltage. The low load at 8 and the relatively large line charging
>>>> capacitance of the 8-9 line help to support the voltage at 8, relative to
>>>> 9.
>>>> Ray
>>>>> On Nov 18, 2015, at 11:11 AM, ALI ZAZOU Abdelkrim
>>>>> <[email protected]> wrote:
>>>>> Hi,
>>>>> my question is about the voltage level of each buses in a radial
>>>>> distribution system. My understanding of this phenomena is that the
>>>>> voltage level of the "farest" (in term of r and x) bus will have the
>>>>> lowest voltage level if there is no generation or voltage regulator
>>>>> between the slack bus and that bus? Am I getting it wright?
>>>>> Because in the above example, based on the modified iee9_bus case given
>>>>> by the tool, i get a strange behaviour. The last bus (8) don't have the
>>>>> lower votage level, so based on that how can that factor be explained?
>>>>> You can find attached to the email, the test case and a figure of the
>>>>> graph of the network.
>>>>> Thank you very much for reading my question
>>>>> Abdelkrim
>>>>> <9_modif.png><case9_modif.m>
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>
