System load margin evaluation using mixed-integer conic optimization

This paper proposes a mixed-integer conic optimization approach for estimating system load margin to evaluate static voltage stability in transmission networks. The proposed problem formulation employs the conic quadratic format of power flow equations, and then utilizes a polyhedral approximation to transform the conic quadratic constraints to linear constraints. Also, the complementary constraint of generators' reactive power limit has been considered. The numerical case studies have been performed on IEEE 14, 30, 39 and 118 bus systems, and validated that the proposed method is an effective tool for system load margin evaluation.