Study on the method of hybrid energy storage to stabilise the power fluctuation of DC microgrid

Currently using hybrid energy storage system to suppress load fluctuation caused by load change is a hot issue. The traditional battery-super capacitor hybrid energy storage system uses low-pass filtering to provide energy and power requirements for each energy storage unit, but it cannot dynamically adjust the filter constant of the filter. The compensation coefficient of the low pass filter changes with the charge and discharge states.Energy storage power is used to determine the target power of the energy storage unit. According to the actual operating conditions of the hybrid energy storage system, an objective function for fluctuations of the DC bus power fluctuations caused by load change is established, and an improved particle swarm algorithm is utilised to find the output power coefficient of each energy storage unit. The output coefficient of the hybrid energy storage control strategy under the improved particle swarm optimisation algorithm has the characteristics of fast convergence and high computational efficiency in the optimisation process. And it will not fall into the local optimal solution;The super capacitor bears more High frequency components and the charge and discharge times of the battery.Comparing with the energy storage coefficient without the compensation coefficient control strategy, the experimental results show that the DC bus power fluctuation caused by the load change can be effectively suppressed, and the peak-to-valley difference of the DC bus is reduced by about 60%.The effectiveness of the control strategy is verified and the service life of the energy storage battery can be lengthened .It has great engineering application value.