Dear MATPOWER Community, I am trying to solve a relatively large (>1000 buses) AC OPF problem. It consists of several individual countries (200-300 buses each). Please allow me to describe my procedures, to paint the full picture.
1. In a first study, I simulated all countries individually. The cross-border power flows to the neighboring countries is known to me from a database. I include these cross-border flows by implementing "pseudo-generators" of zero production cost or "pseudo-demand" at the borders. This procedure works nicely, I get convergence in almost every case I run. 2. Now I would like to simulate not only one country, but all my countries interconnected as one large system. I have "stitched" the transmission grids of the individual countries together in a realistic manner. If I run the OPF without further constraints, I receive converging simulations. But unfortunately, the flow between my countries is massively too high, probably due to price level differences between my countries. I would like to prevent these high cross-border flows, which leads to point 3. 3. I would like to limit the power flow (especially the real power flow) between my countries (so on individual branches in my full system), but am not able to get a converging simulation. I have played around extensively the MVA ratings of the lines (long and short term), but as soon as I impose realistic line ratings, I only get "infeasible solution" problems. As a workaround, I tried replacing the AC cross-border transmission lines with DC lines (and limiting real power flow in those DC lines). This does converge sometimes, but not always. I am using MIPS and/or IPOPT. I would massively appreciate any help in this regard. Some questions about the problem: What is the best ways to limit the power flow in an individual branch? Why are my simulations never converging, if I impose MVA ratings? Has anybody solved such a problem before? It seems quite straightforward, I am sure someone has already done something like this with MATPOWER. What would you suggest me to do? Should I rather use other solvers than MIPS or IPOPT? As I am not an expert of transmission system, what indicators should I be looking at to find out, where my simulations are going wrong? Thanks a lot for your comments. Best Regards, Patrick
