The value of electric vehicles residential charging flexibility in short-term electricity markets

Details

Supervisors

De Jaeger, Emmanuel

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil électromécanicien, à finalité spécialisée: énergie

Abstract

The energy transition is transforming our energy systems. Electricity supply has historically been the most widely used means of flexibility to ensure grid balance, with generation adapting to variations in demand. However, the growing share of Renewable Energy Sources (RES) in the electricity mix makes the supply-side less controllable, requiring the development of new means of flexibility. On the other hand, the electrification of mobility is accelerating. While this represents a challenge for integrating this significant new demand in the grid functioning, it also represents an opportunity to leverage electric vehicles (EVs) charging in the network operations. Residential charging in particular is a suitable candidate to provide flexibility due to long connection time: the charge can be shifted in time without compromising user comfort. It nevertheless remains to be defined how to best exploit EV flexibility potential. This work investigates the value that can be extracted from residential charging flexibility and more specifically the value of optimizing EVs residential charging in Belgian short-term electricity markets (Day-Ahead, Intraday and imbalance markets). The study is simulation based: a virtual fleet of 2000 users is generated, where each user is attributed a yearly set of trips, EV and charger specifications and charging habits intended to represent a realistic Belgian fleet. The fleet charges are optimized on a yearly basis, using historical prices of the year 2023 with the aim of minimizing the cost of recharging. Several strategies involving short-term markets are envisaged. Day-ahead optimization consists of completely redispatching the charges pattern to charge at the cheapest hours. Intraday and imbalance optimizations start from an existing charging plan and generate revenue by occasionally deviating from this plan within a charging session to stop the charge (resell electricity) and restart the charge (rebuy electricity) whenever there are interesting opportunities in these markets. Approaches coupling several markets in a single optimization strategy are also studied. Results showed that smart charging in the day-ahead market enabled a significant cost reduction. Coupling the day-ahead optimization with participation in the imbalance market allows to generate additional income. Results also showed that intensive drivers generate the greatest revenue, with the number of kilometers travelled per year the most important factor influencing the unlocked flexibility. Sufficient nominal charging power is however required to fully exploit this flexibility, with greater charging power enabling more energy to be shifted at the right times. Results finally highlight the importance of the car availability in the generated revenue, demonstrating that more revenue could be generated if the car was more frequently plugged in.