Approximate method for AC transmission switching based on a simple relaxation for ACOPF problems

Transmission switching planning under an AC power flow model is a challenging mathematical problem, incorporating nonlinearities, nonconvexities, and discrete variables. An effective solution methodology would develop an appropriate relaxation and then rely on methods from discrete optimization to simultaneously refine the relaxation, and perform enumeration, so as to obtain a sequence of narrowing lower and upper bounds to the problem. In this paper we discuss a formulation and experiments for the AC power flow transmission switching problem that relies on a simple but relatively accurate relaxation for AC OPF which is easily adapted to discrete optimization methods.