Approximate optimal transmission switching

Optimal transmission switching (OTS) has been proposed as a new control paradigm to improve the economics of electric power systems. The problem is formulated as mixed integer linear programming in which binary decision variables are used to represent the on and off state of transmission lines. In this paper, we propose an approximate model for the OTS problem to achieve better results in terms of solution quality and computation time. We prove the feasibility and optimality properties of our proposed approximate model through theorems. Through numerical studies we show that our proposed approximate model finds OTS solutions with the same electricity generation cost but with lower number of switched transmission lines in the same or less amount of time. Therefore, number of switched transmission lines is reduced to half, one-third, or even less, depending on the case study.