There isn’t a really easy to solve what you want with the current version of MATPOWER, but I think it should be possible to do it with a few “tricks”.
For a branch between bus X and bus Y ... 1. Add two dummy buses X’ and Y’ and reconnect the line to X’ and Y’ instead of X and Y. 2. Add dummy generators at X, X’, Y and Y’ with PMIN = –M, PMAX = M, where M is some value larger than the max flow on the line (even in the relaxed solutions). 3. Add user-defined linear constraints to enforce equality between the Pg of dummy gen at X and -Pg of dummy gen at X’, and likewise for dummy gens at Y and Y’. 4. Set the cost on each of the dummy generators to a piecewise linear function that is zero up to the original line limit value, and some large value above that. 5. Add user-defined linear constraints to enforce equality between the voltages (magnitudes and angles) at X and X’ and at Y and Y’. 6. Remove or relax the original line limit on the line itself. I don’t think I’ve never tried this, so I’d be interested in hearing how well it works if you decide to attempt it. -- Ray Zimmerman Senior Research Associate B30 Warren Hall, Cornell University, Ithaca, NY 14853 USA phone: (607) 255-9645 On Sep 23, 2014, at 5:51 AM, Jiazi Zhang <jzhan...@asu.edu> wrote: > Dear all, > > I'm running AC OPF using Matpower for my project and for some cases, the OPF > does not converge due to the capacities of several branches are not enough. > I'd like to relax the thermal limit constraints on these branches with large > penalty factors. But the power flow thermal limit constraints are nonlinear > for AC OPF. I wonder if it is possible to do such branch limit relaxation in > AC OPF program. > > Best Regards, > Jiazi > > -- > Jiazi Zhang > Research Assisant > School of Electrical, Computer & Energy Engineering > Ira A. Fulton Schools of Engineering > Arizona State University > jzhan...@asu.edu
