Robo-Chargers: Optimal Operation and Planning of a Robotic Charging System to Alleviate Overstay

TL;DR

This paper proposes a systematic approach to optimize the operation and planning of robotic charging systems, called Robo-chargers, to reduce vehicle overstay and improve charging station efficiency.

Contribution

It introduces a novel operation and planning model for Robo-chargers, enabling cost-effective deployment and management of automated charging stations to alleviate overstay issues.

Findings

Robo-chargers significantly reduce vehicle overstay in simulations.

The planning model minimizes total ownership costs considering demand variability.

Sensitivity analysis confirms robustness and practical benefits of Robo-chargers.

Abstract

Charging infrastructure availability is a major concern for plug-in electric vehicle users. Nowadays, the limited public chargers are commonly occupied by vehicles which have already been fully charged. Such phenomenon, known as overstay, hinders other vehicles' accessibility to charging resources. In this paper, we analyze a charging facility innovation to tackle the challenge of overstay, leveraging the idea of Robo-chargers - automated chargers that can rotate in a charging station and proactively plug or unplug plug-in electric vehicles. We formalize an operation model for stations incorporating Fixed-chargers and Robo-chargers. Optimal scheduling can be solved with the recognition of the combinatorial nature of vehicle-charger assignments, charging dynamics, and customer waiting behaviors. Then, with operation model nested, we develop a planning model to guide economical investment on both types of chargers so that the total cost of ownership is minimized. In the planning phase, it further considers charging demand variances and service capacity requirements. In this paper, we provide systematic techno-economical methods to evaluate if introducing Robo-chargers is beneficial given a specific application scenario. Comprehensive sensitivity analysis based on real-world data highlights the advantages of Robo-chargers, especially in a scenario where overstay is severe. Validations also suggest the tractability of operation model and robustness of planning results for real-time application under reasonable model mismatches, uncertainties and disturbances.