Energy storage application has the functions of peak shaving and valley filling, peak regulation and frequency modulation, power-off backup, improving power quality, stabilizing new energy, new energy time shift, etc. There are three advantages of energy storage technology for power grid: first, it helps to increase the penetration rate of renewable energy and promote the development of distributed (micro grid) power generation; second, it improves the stability of power grid and realizes full peak load regulation to reduce peak load and corresponding grid investment and power investment; third, it promotes the liberalization of power market through the design of electricity price.