Hi Mari,
It is only RATE_A that is used by the OPF.
Since the flow at either end of the branch (for AC OPF) are in general not
equal, there are actually two sets of branch flow constraints, those
constraining flow at the “from bus” end and those constraining flow at the “to
bus” end. Usually, if a flow constraint is binding, it is binding only at one
end, but this is not always the case. In any case, adding the two multipliers
together should give you the sensitivity of the objective function to changes
in RATE_A.
Ray
> On May 5, 2015, at 6:49 AM, Mari Hardersen Prydz <[email protected]> wrote:
>
> Dear all,
>
> I'm running the ACOPF on different test cases, and would like to find the
> effect on the objective function value when changing the thermal limits (rate
> A, B and C).
>
> Firstly, is it only rate A that limits the power flow, or will rate B and C
> also affect this?
>
> So far I have looked at the multipliers MU_SF and MU_ST
> (bresults.branch(i,18) and bresults.branch(i,19)), but I'm not sure how to
> put these two values together to represent the branch (as the thermal limits
> are set for the branches and not each node).
>
> Is there another dual variable for the branch flow constraints that
> represents the branch and not the to and from node?
>
>
>
> Thanks for any help on the subject.
>
> Sincerely,
>
> Mari Prydz
> Norwegian University of Science and Technology
>
>
>
