Vids,
It looks correct to me. Are you sure that it isn’t just that a large amount of
negative VArs are needed to satisfy all of the voltage and line flow
constraints?
Ray
> On Oct 17, 2014, at 3:59 PM, vids <[email protected]> wrote:
>
> Dear Dr Ray,
>
> I was able to implement what i wanted when I said I was trying to
> implement an OPF where the real power dispatch is
> pre-determined (as in the case of an energy market where the Q
> schedules are managed separately by the transmission operator), by
> fixing the Pmin=Pmax equal to the energy schedules, and allowing only
> one "slack" bus to move, since the real power variation was only
> minimal.
>
> Now I am trying to determine an optimum "reactive power schedule" by
> trying to simulate the given the current ancillary service payment
> arrangement here in our country. The reactive power outputs of
> generators beyond 0.9 lead and 0.85 lag are paid with fixed 4$/kVAr
> cost. All reactive power generated within these limits are not
> compensated.
>
> So i tried to model this scenario by using a piecewise linear cost
> function for generators. The cost function below is for one specific
> generator in my data.
>
> 1 0 0 5 -78 4000 -51.82 -0.000001 0 0
> 66.3 0.000001 102 4000;
>
> Please see attached figure for the cost function I wanted to achieve.
> Basically I wanted the solution of the OPF to schedule as much MVArs
> in region A. However it seems that because of the (-) negative term
> for the reactive power absorption, it tends to schedule more MVArs in
> region B.
>
> Did I use the piecewise linear function correctly? How can I improve
> my cost function model to achieve the least amount of VArs shceduled
> outside region A? Thank you very much Sir.
>
> Vids
>
> On Fri, Oct 17, 2014 at 2:52 AM, Ray Zimmerman <[email protected]> wrote:
>> If you used the A, l and u fields of the MATPOWER case struct (mpc) to
>> specify the constraints, then the multipliers are in …
>>
>> results.lin.mu.l.usr
>> results.lin.mu.u.usr
>>
>> Note that these will be relative to power in p.u. not in MW, so you’ll have
>> to divide by baseMVA to get prices in $/MW.
>>
>> --
>> Ray Zimmerman
>> Senior Research Associate
>> B30 Warren Hall, Cornell University, Ithaca, NY 14853 USA
>> phone: (607) 255-9645
>>
>>
>> On Oct 16, 2014, at 12:52 PM, vids <[email protected]> wrote:
>>
>> Hi Dr Zimmerman,
>> How do i access the multipliers for the additional constraint that I
>> added? thank you
>>
>> On Tue, Sep 2, 2014 at 10:26 PM, Ray Zimmerman <[email protected]> wrote:
>>
>> Can you accomplish what you want simply by including the base dispatch in
>> the PD column of the bus matrix (where injections would appears as negative
>> loads)?
>>
>> --
>> Ray Zimmerman
>> Senior Research Associate
>> B30 Warren Hall, Cornell University, Ithaca, NY 14853 USA
>> phone: (607) 255-9645
>>
>> On Aug 28, 2014, at 10:10 PM, vids <[email protected]> wrote:
>>
>> Thank you very much, Dr. Shri. Yes i think your suggestion about
>> making the delta Pg as the control variables is a great idea. However
>> I am new to Matpower. Can you help me/ direct me to some examples on
>> how i can accomplish this? Thank you very much...
>>
>> On Thu, Aug 28, 2014 at 12:23 AM, Abhyankar, Shrirang G.
>> <[email protected]> wrote:
>>
>> Vids,
>> Implementing your reformulated OPF equations, written in complementarity
>> form, is non-trivial in MATPOWER as it will require modifying the
>> variable/equation sizes and muddling with the OPF data structures. Note
>> that you'll also need additional equations, perhaps expressed in
>> semi-smooth form, relating your upward/downward balancing service to
>> generator power deviation. You will have to spend some time to understand
>> the OPF data structures and how they are used in the various OPF routines.
>>
>> One other possible way (that I think will work) is by using the real power
>> generator deviation \Delta{Pg} as the control variable instead of Pg (see
>> the attached equations). This will keep the sizes of the
>> variables/equations for the reformulated OPF same as the original one.
>> However, you will have to modify the cost function, gradient, Hessian, and
>> the generator real power limits accordingly.
>>
>> Shri
>>
>> -----Original Message-----
>> From: vids <[email protected]>
>> Reply-To: MATPOWER discussion forum <[email protected]>
>> Date: Wed, 27 Aug 2014 16:18:14 +0800
>> To: <[email protected]>
>> Subject: Modifying the Power Balance Equations
>>
>> Hi Dr Zimmerman and Matpower Community,
>>
>> I am trying implement an OPF where the real power dispatch is
>> pre-determined (as in the case of an energy market where the Q
>> schedules are managed separately by the transmission operator).
>>
>> Is it possible to implement it in Matpower? My idea is to add "slack"
>> variables in the nodal energy equations
>>
>> Pgi - ΔPgi + Pb1i - Pb2i - Pdi = ΣViVjYij(cos(θij + δi -δj)
>>
>> Pgi - fixed/predetermined real power generated at node i
>> ΔPgi - real power 're-scheduling' due to the reactive power dispatch
>> Pb1i - upward balancing service at node i
>> Pb2i - downward balancing service at node i
>>
>> Pb1i and Pb2 will have non-zero values when ΔPgi is nonzero, prompting
>> other generators to compensate the real power 're-scheduling' when
>> needed.
>>
>> This is the formulation in the dissertation of Dr. El-Samahy, and I
>> am wondering if this can be implemented in matpower.
>>
>> Any ideas would greatly be appreciated. Thank you very much.
>>
>> --
>> 2 Cor 12:9
>> Each time he said, "My grace is all you need. My power works best in
>> weakness." So now I am glad to boast about my weakness, so that the
>> power of Christ can work through me.
>>
>>
>>
>>
>>
>>
>> --
>> 2 Cor 12:9
>> Each time he said, "My grace is all you need. My power works best in
>> weakness." So now I am glad to boast about my weakness, so that the
>> power of Christ can work through me.
>>
>>
>>
>>
>>
>>
>> --
>> 2 Cor 12:9
>> Each time he said, "My grace is all you need. My power works best in
>> weakness." So now I am glad to boast about my weakness, so that the
>> power of Christ can work through me.
>>
>>
>>
>
>
>
> --
> 2 Cor 12:9
> Each time he said, "My grace is all you need. My power works best in
> weakness." So now I am glad to boast about my weakness, so that the
> power of Christ can work through me.
> <cost function.jpg>
