Combined Provision of Economic Dispatch and Frequency Regulation by Aggregated EVs Considering Electricity Market Interaction

A combined delivery of economic dispatch and frequency regulation (FR) services from electric vehicles (EVs) is proposed to exploit the dynamic flexibility of EV charging load and its revenue opportunities in the electricity markets. The economic feasibility is assessed with the combined operation model of EVs for optimal bidding in the day-ahead energy market and FR market. The proposed optimization adopts the hierarchical control framework with EV aggregator (EVA) as the intermediate control unit to interact with the power system operator. As EVs are paid for FR based on their actual performance, a dynamic control strategy for charging EVs in response to regulation signals is developed to validate the technical feasibility of combined operation. The autonomous control of EVA modulates the charging of each EV to ensure the optimal charging schedules and real-time frequency control. A case study reveals that the profitability of EV charging control can be significantly increased by energy cost reduction and additional regulation revenue. The proposed dynamic control with a novel power-sharing strategy of EVA provides effective frequency support based on the optimal charging schedule and capacity bids without violating charging demand and availability constraints of each individual EV.