Response Capability Evaluation of EV Aggregator and Application in Energy and Reserve Markets

Electric vehicles (EVs) can provide multiple auxiliary services for electric power system and obtain certain economic benefits utilizing vehicle-to-grid (V2G) technology. As an agent between the power grid and EV customers, quantitatively evaluating response capability (RC) of electric vehicle aggregator (EVA), i.e., charging and discharging power ranges, ahead of time is of fundamental importance for its participating in electricity markets. However, it is difficult to evaluate RC of individual EV separately due to the stochastic characteristics of travel behaviors of EV customers. To this end, this paper establishes an EV aggregation model to evaluate the aggregate RC of EVA considering the power and energy constraints of entire EVs fleet, and therefore reduces the difficulty to forecast charging demands of EVs fleet. Then, the mathematical elaboration of evaluation method is developed based on the established model. Moreover, to guarantee the accuracy of the evaluation results while meeting the driving demands of EV customers, a heuristic control strategy which considers response time (RT) and state of charge (SOC) indicators comprehensively is designed. Finally, the application of the RC evaluation method for EVA participating in energy and reserve markets is illustrated. The uncertainty of electricity price and the difference between up and down reserve prices are considered in this paper. The case study using a statistical data from EU MERGE project validates the effectiveness of the proposed method.