Risk-averse forward contract for electric vehicle frequency regulation service

Electric vehicles (EVs) can be coordinated by an aggregator to participate in the electricity day-ahead market (DAM) and provide frequency regulation service. In the DAM, a short-term forward contract is made between the aggregator and an independent system operator (ISO). The contract specifies the contract size, which is the amount of regulation capacity provided by the aggregator for each hour of the next day. However, since the capacity of the aggregator is provided by many EVs instead of a single source, the challenge is how to efficiently aggregate the small and uncertain individual capacity and determine the optimal size of the forward contract. We consider two cases for the contract between the aggregator and the ISO. In the first case, the aggregator needs to ensure that the capacity provided by the EVs on the next day will meet the amount specified in the contract. In contrast, in the second case, the ISO allows an update of the contract size. A stochastic program is formulated to determine the contract size for both cases. Our problem formulation incorporates risk management using the conditional value at risk (CVaR). Chance constraints are embedded when the contract size is fixed. We tackle the chance constraints using the Markov inequality and propose an efficient algorithm. The EV charging data collected in the province of British Columbia, Canada, is used to evaluate the performance of the proposed algorithm. Simulation results show that the proposed algorithm improves the revenue of the aggregator compared to an existing algorithm from the literature.