Automated Network Decomposition and Relaxed Boundary-Consensus Distributed Power Flow

Power flow analysis is fundamental to power system planning, but repeated full-network solutions become increasingly demanding as system size and scenario volumes grow with distributed energy resources. This paper develops and validates a partitioned power flow framework built around PSS®E, which is treated as a closed commercial solver without access to its Jacobian or internal solver state. The framework comprises three stages: network partitioning, automated case decomposition, and iterative boundary coordination. Spectral clustering based on real power flow, inverse reactance, and Z-bus electrical distance is compared with METIS multilevel graph partitioning using solver-independent graph metrics, quantifying the trade-off between regional balance and interface size. The resulting bus-to-zone allocation is automatically converted into independently solvable regional cases in which the far end of every inter-zone tie-line is represented by a virtual reference bus. A master–worker scheme then solves the regional cases in parallel and reconciles the voltage magnitude and phase angle of every duplicated interface bus through a relaxed boundary-consensus update, which is accelerated by Aitken extrapolation or Anderson acceleration. The framework is validated against the centralized PSS®E Newton–Raphson solution on the IEEE 30-bus, IEEE 300-bus and 6717-bus Texas synthetic systems. Both solutions are obtained under the same controls-locked conditions: transformer taps, phase shifters and switched shunts are held at their case settings and generator reactive-power limits are not applied. The comparison covers bus voltage magnitudes and angles, active and reactive power at both ends of every tie-line, total network losses, and the power-balance residual of the reassembled solution. Under these conditions, every configuration converged from a flat start with both accelerators; the largest voltage-magnitude and angle deviations from the centralized solution are 9.2×10−5 p.u. and 0.043°, and tie-line active power agrees to within 0.12% of the largest tie-line flow of each system (at most 0.49 MW). Coordinating discrete controls and reactive-power limits across regions is left to future work. The partitioned implementation does not provide a wall-clock speed-up on the workstation (14 logical processors). Instead, the results demonstrate the feasibility of a fully automated domain-decomposed power flow workflow around an unmodified commercial solver and quantify the accuracy and computational trade-offs of boundary-based regional coordination.