Dynamic Expansion Planning of Charging Stations With Fixed and Mobile Chargers

Truck mobile chargers (TMCs) with high-capacity batteries can alleviate peak grid pressure and reduce fixed charger idleness during non-peak periods. Although TMCs are already in use, existing charging station expansion plans rarely account for their integration. To meet growing but fluctuating charging demand and enhance station resilience, this study optimizes charger deployment by jointly considering fixed chargers and TMCs, with attention to expansion cost, service quality, and utilization. The model determines the optimal number of fixed chargers to install, the number of TMCs to rent, and their rental durations. Based on Monte Carlo-simulated scenarios generated from historical data, a sample average approximation (SAA) method is employed to support robust decision-making under uncertainty. Applied to a highway service area in China, the strategy keeps peak waiting under 10 minutes, improves robustness, and increases utilization by 17-18%. Management suggestions are also provided to support sustainable transportation planning.