Fairness-Guaranteed Online Power Allocation Policies for EV Fast Charging Stations
The rapid expansion of electric vehicles (EVs) necessitates scalable fast charging station (FCS) infrastructure. These stations are often oversubscribed, with total port rating exceeding a station-level power cap. In such settings, fair real-time power allocation is essential to secure equitable access while maximizing infrastructure utilization. Existing methods typically assume conventional FCS architectures, depend on prior battery or charge curve data, and lack theoretical guarantees in online settings. To address these limitations, this paper proposes computationally efficient, fairness-guaranteed online power allocation policies for both conventional and modular FCSs that use only instantaneous power requests. Drawing from fair division theory, we formalize a fairness framework with envy-freeness, Pareto efficiency, and proportionality as per-slot criteria, together with a fairness criterion defined over the charging session. For conventional FCSs, Fair-Opap-C follows the classical progressive filling algorithm and guarantees a fair allocation, and we prove that, under a mild condition on the charge curve, it also satisfies the session-level fairness criterion. For modular FCSs, we propose Fair-Opap-M, a novel policy that guarantees a fair allocation, and establish bounds on its session-level fairness under conditions on EV power requests. Simulations against seven benchmarks from EV charging and fair division literature show that the proposed policies satisfy all per-slot fairness criteria and attain the highest session-level fairness among policies that fully utilize station capacity. Both scale as O(n log n) in the number of connected EVs and run below 1.3 ms with 500 connected EVs, orders of magnitude faster than optimization-based approaches.