Impact of Lead Time on Aggregate EV Flexibility for Congestion Management Services

TL;DR

This study examines how lead time influences the flexibility of aggregated EV charging for grid congestion management, highlighting the importance of scheduling, product type, and EV charging modes on effectiveness and costs.

Contribution

It provides a quantitative analysis of lead time effects on EV fleet flexibility and compares bidirectional and unidirectional charging impacts on costs and emissions.

Findings

Flexibility variation depends on BAU schedules, flexibility duration, and start time.

Bidirectional (V2G) charging outperforms unidirectional charging in all scenarios.

Flexibility products influence energy costs and emissions.

Abstract

Increased electrification of energy end-usage can lead to network congestion during periods of high consumption. Flexibility of loads, such as aggregate smart charging of Electric Vehicles (EVs), is increasingly leveraged to manage grid congestion through various market-based mechanisms. Under such an arrangement, this paper quantifies the effect of lead time on the aggregate flexibility of EV fleets. Simulations using real-world charging transactions spanning over different categories of charging stations are performed for two flexibility products (redispatch and capacity limitations) when offered along with different business-as-usual (BAU) schedules. Results show that the variation of tradable flexibility depends mainly on the BAU schedules, the duration of the requested flexibility, and its start time. Further, the implication of these flexibility products on the average energy costs and emissions is also studied for different cases. Simulations show that bidirectional (V2G) charging outperforms unidirectional smart charging in all cases.