A Level-Regularized Two-Oracle Benders Decomposition for Generation-Transmission Expansion Planning

Generation and transmission expansion planning is commonly addressed via Benders decomposition coupled with an operational model. Big-$M$ formulations used to enforce Kirchhoff's Voltage Law (KVL) on candidate circuits distort Benders cuts: dual multipliers become scaled by large constants, producing oscillatory investment signals. We propose a two-oracle framework that separates well-conditioned cut generation, provided by a relaxed-KVL oracle, from exact feasibility-enforcing cuts obtained from the standard subproblem. The master problem is stabilized by level regularization. Preliminary results on a real system indicate fewer oscillations and faster gap reduction compared to traditional approaches.