An ADMM-Based Distributed Optimization Method for Solving Security-Constrained Alternating Current Optimal Power Flow.

When optimizing electric power system operational decisions, it is of great importance to prevent potential failures in both the system operation and the optimization algorithm. In "An Alternating Direction Method of Multipliers-Based Distributed Optimization Method for Solving Security-Constrained Alternating Current Optimal Power Flow," Gholami, Sun, Zhang, and Sun propose a novel two-level algorithm that (1) effectively prevents power system operational failures through consideration of impactful contingencies and (2) guarantees convergence when parallelized on a computing cluster with multiple nodes. Extensive numerical experiments suggest that the proposed algorithm is able to provide high-quality feasible solutions under the time limit of 10–45 minutes for various synthetic and industrial networks with up to 30,000 buses and 22,000 contingencies, comparable with the size of the U.S. power grid. In this paper, we study efficient and robust computational methods for solving the security-constrained alternating current optimal power flow (SC-ACOPF) problem, a two-stage nonlinear optimization problem with disjunctive constraints, that is central to the operation of electric power grids. The first-stage problem in SC-ACOPF determines the operation of the power grid in normal condition, whereas the second-stage problem responds to various contingencies of losing generators, transmission lines, and transformers. The two stages are coupled through disjunctive constraints, which model generators' active and reactive power output changes responding to system-wide active power imbalance and voltage deviations after contingencies. Real-world SC-ACOPF problems may involve power grids with more than 30,000 buses and 22,000 contingencies and need to be solved within 10–45 minutes to get a base case solution with high feasibility and reasonably good generation cost. We develop a comprehensive algorithmic framework to solve SC-ACOPF that meets the challenge of speed, solution quality, and computation robustness. In particular, we develop a smoothing technique to approximate disjunctive constraints by a smooth structure that can be handled by interior-point solvers; we design a distributed optimization algorithm to efficiently generate first-stage solutions; we propose a screening procedure to prioritize contingencies; and finally, we develop a reliable and parallel computation architecture that integrates all algorithmic components. Extensive tests on industry-scale systems demonstrate the superior performance of the proposed algorithms. History: This paper has been accepted for the Operations Research Special Issue on Computational Advances in Short-Term Power System Operations. Funding: The authors acknowledge the continued support of ARPA-E [Grant DE-AR0001089] and the National Science Foundation [Grant 1751747]. Supplemental Material: The e-companion is available at https://doi.org/10.1287/opre.2023.2486. [ABSTRACT FROM AUTHOR]