The characteristic of electric vehicle charging is that the charging power is large and has great impact on the power grid, but the total power consumption is not large. As the number of electric vehicles and their charging power increases, charging stations have requirement to increase the number and power of charging piles, which requires increasing power distribution capacity. The traditional way is to add distribution transformers, but the cost is high, and the actual utilization rate of the transformers is low. The best way is to configure an energy storage system to achieve dynamic capacity increase.