Perhaps you can try to run an AC OPF with branches that are represented
only by the series reactance (no line charging capacitance nor
resistance); one of the AC solvers might be able to solve the resulting
problem.
Carlos.
Enrico Vaccariello wrote:
Dear all MATPOWER developers and users,
I will briefly explain my issue.
I am trying to run a DC-OPF on my 285-bus case, whose generators
costs' curves have been defined as second-order polynomials.
Some of these polynomials have negative convexity, as the one shown by
the red line of the graph I am attaching.
When I try to run the DC-OPF it does not converge. This happens with
all the simplex, dual-simplex and primal-simplex OT and the MIPS solver.
In the case of the first three linprog solvers, I get the error
message: "The problem is non-convex".
Therefore, I have changed the convexity of my cost curves polynomials,
just as a test, by modifying their first coefficient:
mpc.gencost(:,5)=abs(mpc.gencost(:,5)). The result of the changes is
shown by the blue curve of the graph I am attaching. Both the curves
refer to the same CCGT generator.
Performing the same DC-OPF simulation with such modifications leads to
convergence.
Therefore (excuse me if that's trivial) the convexity of the cost
curves guarantees the convexity of the objective function.
Anyway, since my actual cost curves are non-convex, could you please
indicate any other solver allowing to work with non-convex objective
functions?
Thank you, any help will be very appreciated.
Best regards,
Enrico
