Stochastic modeling of EV on-board chargers for fast frequency response under communication delays

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Shi, Xiang and Bayram, I. Safak and Galloway, Stuart (2026) Stochastic modeling of EV on-board chargers for fast frequency response under communication delays. IEEE Open Journal of Vehicular Technology, 7. pp. 817-828. ISSN 2644-1330 (https://doi.org/10.1109/OJVT.2026.3666359)

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Abstract

The rapid electrification of the transportation sector offers a promising avenue for ancillary services through Vehicle-to-Grid (V2G) applications. This is particularly critical for low-inertia systems, such as the U.K. grid, where the transition toward converter-based renewable generation necessitates very fast frequency response. Therefore, the viability of V2G for high-value frequency markets is constrained by strict latency requirements (e.g. one second)). Existing literature has predominantly focused on high-level economic aggregation models or communication network delays, largely neglecting the stochastic physical response dynamics of the EV On-Board Charger (OBC). This paper addresses this gap by developing a discrete-time Markov chain model that specifically characterizes the internal dynamics and response latency of OBC hardware. We integrate this model into a discrete-event simulation framework to evaluate end-to-end system latency, coupling stochastic OBC constraints with Over-the-Air (OTA) communication delays. We analyze the performance of fleets comprised of three common OBC ratings: 10 kW, 22 kW, and 43 kW. Contrary to the intuition that higher power ratings yield superior agility, our results demonstrate that high-capacity chargers may exhibit lower success rates in fast frequency markets due to insufficient ramp-rate-to-capacity ratios. Furthermore, we demonstrate that the frequency of mode switching events (switching between charging and discharging) is a dominant factor in performance degradation due to hardware hysteresis. These findings underscore that the efficacy of V2G applications requires precise EV-level control logic rather than relying solely on fleet-level optimization. Finally, the proposed models are evaluated against the PJM interconnection’s composite score methodology. The results demonstrate high accuracy, suggesting the proposed framework can serve as a preliminary, EV-specific V2G assessment tool for market operators.

ORCID iDs

Shi, Xiang ORCID logoORCID: https://orcid.org/0009-0007-5244-8375, Bayram, I. Safak ORCID logoORCID: https://orcid.org/0000-0001-8130-5583 and Galloway, Stuart ORCID logoORCID: https://orcid.org/0000-0003-1978-993X;
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