Analysis of Influence of Aggregated Electric Vehicle Load on Power System Flexibility with High Photovoltaic Penetration

Under the new electric power system, both supply and demand sides exhibit significant randomness and volatility, posing challenges to the electric power grid's ability to handle net load fluctuations. While ensuring the capability and quality of power supply, considering the interaction between sources, grids, loads, and storage, and analyzing the demand for electric power grid carrying capacity and the contributions of various resources, can continuously optimize investment decision-making approaches to better support the safe and stable operation of the electric power grid. This approach not only enhances the system's flexibility but also achieves high proportions of new energy consumption, striving for greater profit margins. This paper approximates the responsive capability of electric vehicles as an zonotope model, and uses the Minkowski sum method to obtain the feasible domain of the aggregator, while considering the carrying capacity changes of energy storage resources and substations in response to fluctuations, to analyze the aggregation situation of electric vehicles under the risk of avoiding net load fluctuation. In the case study, the response capability of demand-adjustable resources within the area during the evening peak period was analyzed. Considering a net load volatility of 10%, the contribution of generation, load, and storage to the distribution network's carrying capacity was assessed. Under this scenario, aggregating electric vehicles to a proportion of 25.8% can effectively handle the adjustment margin required for net load fluctuations during the late peak hours, thereby enhancing the distribution network's capacity to cope with uncertainties and, in turn, increasing the flexibility of the power system.