Hi Ray, Thank you for your reply. In my current research I use AC OPF, so the problem is not easy. I tried to solve this issue by adding in every bus two virtual generators - the first one with positive and the second with negative generation, both with very high costs. In consequence virtual generators produce power only when there is no any other way to meet branch limits. But it sometimes works fine, and sometimes not. I wonder what can be the reason of such behaviour?
Best regards Roman ----- Original Message ----- From: Ray Zimmerman To: MATPOWER discussion forum Sent: Tuesday, April 09, 2013 8:58 PM Subject: Re: Branch limits as "soft" constraints Hi Roman, In the current version of MATPOWER there is no easy way to do this for AC OPF problems, since the flows are non-linear functions of the optimization variables. It is possible to add user-defined costs on the DC model flows using the mechanism described in sections 5.3.1 and 6.1 of the User's Manual, since they are linear functions of optimization variables. -- Ray Zimmerman Senior Research Associate 419A Warren Hall, Cornell University, Ithaca, NY 14853 phone: (607) 255-9645 On Apr 9, 2013, at 11:26 AM, Roman Korab <[email protected]> wrote: Hello Matpower users! I wonder if is possible to treat the thermal branch limits as a "soft" constraints in Matpower OPF procedures? For example, when I make some OPF calculations in order to determine effectivness of cross-border real power flow control by using phase shifting transformers, for some settings of PST, OPF don't converge. The main reason is that some branches have not enough capacity to transmit more power. Is there any simple way to overcome mentioned problem, for example, by automatic treatment the thermal limits of such branches not as a strict constraints, but as constraints that can be exceeded? Best regards Roman
