I tried using mpc.user_constraints.nli = {.....} as suggested by the
manual. I created 2 functions one which returns constraint values and
gradients and one which returns the hessian. After adding the field to mpc,
I used runopf. It showed an error saying "Not enough input arguments" in
the line where I use x to calculate constraint value in nli_constraint
(from the code below).
mpc = loadcase('case5.m')
mpc.user_constraints.nli = {{'cost', 5, nli_constraint,
nli_constraint_hess}}
r = runopf(mpc)
nli_constraint and nli_constraint_hess were functions I created with x and
x, lambda as input arguments respectively.
Could you guide me as to where I might be going wrong with this?
Regards
Viswanath
On Thu, Oct 19, 2017 at 11:31 AM, Viswanath Hariharan <[email protected]>
wrote:
> Sir
> So where does these functions obtain x and where does the hess function
> obtain lambda from?
> Because when I define these functions and I provide X and lambda as
> inputs, it'll show error, I thought.
>
> Regards
> Viswanath
>
>
> On Oct 19, 2017 10:47 AM, "Ray Zimmerman" <[email protected]> wrote:
>
>> Hi Viswanath,
>>
>> Since your constraint is an inequality, let’s call it h(x). And since,
>> h(x) <= 0, you need to define it as …
>>
>> h(x) = x'Hx + e'x + C – N
>>
>> 1. The function you need to implement computes the Hessian of lambda’ *
>> h(x) for a given value of lambda and x. Both lambda and x are provided as
>> inputs, you provide the Hessian of lambda’ * h(x) as output. Since h(x)
>> (and also lambda) is a scalar in your case, the Hessian is simply lambda *
>> H.
>>
>> 2. I assume N is a constant that is entered as part of your definition of
>> h(x).
>>
>> Ray
>>
>>
>> On Oct 18, 2017, at 3:10 PM, Viswanath Hariharan <[email protected]>
>> wrote:
>>
>> Sir
>> I have a doubt about the method you asked me to try to add non-linear
>> constraints.
>> The constraint I want to add is x'Hx + e'x + C < = N (where N is cost
>> let's say 20000 or 15000).
>>
>> The above method asks me to create 2 functions, one that calculates
>> gradient values and constraint values and the other that calculates Hessian
>> of one of the lagrangian term that consists of lambda.
>>
>> 1. Say f = x'Hx + e'x + C < = N, Should I be computing the hessian of
>> lambda*f ? How do I compute lambda?
>> 2. Also, could you guide me as to where should I be inputting N?
>>
>> Thank you.
>>
>> Regards
>> Viswanath
>>
>> On Thu, Oct 5, 2017 at 10:41 AM, Ray Zimmerman <[email protected]> wrote:
>>
>>> *(Btw, simply reply to the list, no need to copy the list owner)*
>>>
>>> MATPOWER 6.0 and earlier does not have the capability to add nonlinear
>>> constraints to the OPF. However, this feature was just added to the master
>>> branch in GitHub <https://github.com/MATPOWER/matpower/>. See options 2
>>> or 3 under “Getting MATPOWER” in the README
>>> <https://github.com/MATPOWER/matpower/blob/master/README.md>. The PDF
>>> manual for the latest development version of MATPOWER can typically be
>>> found here:
>>>
>>> https://www.dropbox.com/s/3qkji1cuyi075uj/MATPOWER-manual.pdf?dl=0
>>>
>>> You’ll probably want to use the method described in Section 7.1.2 for
>>> Nonlinear Constraints. In particular, you’ll want to look at the example
>>> mentioned in t_opf_mips().
>>>
>>> Hope this helps,
>>>
>>> Ray
>>>
>>>
>>>
>>> On Oct 4, 2017, at 5:59 PM, Viswanath Hariharan <[email protected]>
>>> wrote:
>>>
>>> Hello Sir
>>> I want to add non linear cost constraints to the opf solver.
>>> cost = x'Hx + C'x + constant <= 20000
>>>
>>> How do I use the add_constraints function to add this constraint? Should
>>> I be adding new fields to om and then should I be passing it to
>>> add_constraints?
>>>
>>> Regards
>>> Viswanath Hariharan
>>>
>>>
>>>
>>
>>
