Interior-Point vs. Spatial Branching Approaches for Solving the AC Optimal Power Flow Problem

Abstract: The AC Optimal Power Flow (AC-OPF) problem is a non-convex, NP-hard optimization task essential for secure and economic power system operation. Two prominent solution strategies are interior-point methods, valued for computational efficiency, and spatial branching techniques, which provide global optimality guarantees at higher computational cost. In this work, we also explore data-boosted variants that leverage historical operating data to enhance performance by guiding initialization in interior-point methods or constraining the search region in spatial branching. We conduct a comprehensive empirical comparison across networks of varying sizes and under both standard benchmark conditions and modified configurations designed to induce local optima. Our results show that data-boosted strategies can improve convergence and reduce computation times for both approaches. Spatial branching, however, remains computationally demanding, requiring further development for practical application. In contrast, modern interior-point solvers exhibit remarkable robustness, often converging to the global optimum even in challenging instances with multiple local solutions.