Flexible interconnection of highway service-area multi-microgrids via mobile energy storage: A coordinated stochastic planning framework

The rapid electrification of highway transportation is increasing electric-vehicle charging demand at highway service areas, particularly in weak-grid and off-grid regions where reliable power supply is difficult to guarantee. Conventional self-contained service-area energy systems mainly rely on local renewable generation and stationary storage, which may lead to redundant capacity investment because spatial complementarity among geographically distributed service areas is not fully exploited. This paper proposes a mobile-energy-storage system (MESS)-enabled flexible interconnection framework for coordinated planning of highway service area self-contained multi-microgrid systems (HSA-SCMMSs). In the proposed framework, mobile energy storage systems serve as inter-station energy carriers, enabling spatially and temporally adaptive energy sharing without permanent tie-line infrastructure. A two-stage coordinated stochastic planning model is developed to jointly optimize photovoltaic generation, wind generation, stationary energy storage, EV charging facilities, backup supply, and mobile energy storage capacity under renewable-generation, traffic-flow, and infrastructure-load uncertainties. To improve computational tractability, a hierarchical solution method is designed, where Progressive Hedging enforces scenario-wise capacity consistency and adaptive consensus alternating direction method of multipliers (ADMM) algorithm coordinates MESS-induced spatial coupling. Case studies based on three highway service areas in Xinjiang, China, show that the proposed method maintains 100% supply adequacy and reduces the annualized total cost by 4.37%, 15.52%, and 4.15% compared with isolated planning, fixed tie-line interconnection, and sequential MESS deployment, respectively. The proposed decomposition algorithm reduces computation time by at least 71.88% compared with single-layer decomposition methods. These results demonstrate that mobile-energy-storage-enabled flexible interconnection provides a cost-effective and infrastructure-light alternative for coordinated highway service-area energy planning.