Test and Analysis of Energy Efficiency of Energy Storage System in Power Plant Providing Frequency Regulation Ancillary

Energy efficiency is an important indicator of the economy of energy storage system, but related research mainly focuses on batteries, converters or energy storage units, and there is a lack of research on the actual energy efficiency of large energy storage system. In this paper, the energy efficiency is tested and analyzed for 20 energy storage system participating in frequency regulation ancillary in Guangdong Province. The results show that the energy efficiency of low power charge-discharge is generally better than that of high power charge-discharge, while the percentage of auxiliary energy consumption of low power and small capacity system is higher; the overall efficiency of energy storage system is affected by the system capacity, charge-discharge rate and auxiliary energy consumption.