Capacity configuration strategy of SOEC- battery based hybrid energy storage system for suppressing fluctuation of wind power

Currently, Chinese wind farms are generally equipped with 10% rated capacity lithium-ion battery energy storage system, which often fails to smooth out wind power fluctuation effectively and fulfill the power grid connection standard. The hybrid energy storage system combining with the solid oxide electrolysis cell (SOEC) and lithium-ion battery system can be adopted to suppress the wind power fluctuation. Firstly, the model of the hybrid energy storage system is built and the transient response characteristics is analyzed in Matlab/Simulink environment. Secondly, the capacity configuration strategy of the hybrid energy storage system is developed with the variational mode decomposition method. Thirdly, the coordinated control algorithm of the hybrid energy storage system is proposed considering the state of charge control for the lithium-ion battery system and the transient response characteristics of SOEC. Finally, the presented methods are verified through simulation based on the actual wind farm power data with the 15 MW rated installed capacity of the wind farm in Shandong Province China. The results indicate that the developed methods can suppress the wind power fluctuation and meet up the power grid connection standard successfully. The range of state of charge for the battery system is from 0.497 to 0.512, which is within the boundary conditions. The electric efficiency of the SOEC system is from 0.817 to 0.972, and the power consumption is from 2.968 to 3.461 kWh/Nm 3 H 2 during the hydrogen production, who are all within the threshold values.