An adaptive energy allocation strategy for battery/supercapacitor hybrid energy storage system

Battery/supercapacitor hybrid energy storage system is widely used in renewable energy grid since its excellent power and energy performances. However, the load and grid output power may fluctuate drastically, resulting in the dc bus voltage rise or fall sharply. The power demand is composed of both high-frequency and low-frequency component that brings some difficulties to energy distribution. Therefore, it is still a challenge to design a safe and high-efficiency energy allocation strategy to respond to the power demands and stabilize the bus voltage in time. In this paper, an adaptive energy allocation strategy based on the isolation frequency is proposed to address this challenge. The isolation frequency is adjusted adaptively that can improve the energy utilization ratio and ensure the energy storage element safety. In addition, a practical control method based on frequency-domain analysis is adopted since its less computation. Simulation results validate the potential advantages and effectiveness of the proposed strategy.