A Two-Level Approach to AC Optimal Transmission Switching with an Accelerating Technique

DC-based optimal transmission switching (OTS) cannot consider ac feasibility, which hinders the exploitation of the benefits of OTS in power system operations. This paper proposes a new OTS approach that considers ac feasibility. The approach uses a two-level iterative framework in which a mixed integer second-order cone programming OTS model provides candidate solutions at the upper level, while the ac feasibility check is conducted at the lower level. An accelerating technique is developed to significantly improve the computational efficiency while maintaining accuracy. Case studies using the IEEE 57-bus system, the IEEE 118-bus system and a real-world large system demonstrate the efficacy of the proposed approach.