Transmission congestion management through optimal transmission switching

In both restructured and vertically integrated power systems, it is desirable to transmit power to remote locations without causing any congestion and consequently avoiding inefficiency in generation dispatch. In this paper, in order to relieve network congestion, transmission switching is employed as a powerful tool to change network topology which consequently yields lower energy prices and higher market efficiently. Here, transmission switching problem is formulated as a DC optimal power flow (DCOPF) problem with binary variables and is solved using mixed integer programming (MIP). In addition, a procedure is presented, which examines the impacts of switching on system security in more details by means of an ACOPF problem. In order to test the feasibility and effectiveness of the method, a 5-bus and the IEEE 14-bus systems have been used. In order to study the impact of switching, a number of system variables have been studied including: generation cost, congestion rent, locational marginal price (LMP), voltage profile and transmission losses. The results demonstrate that transmission switching is able to successfully remove congestion as well as reducing system cost and hence leading to lower energy prices.