The structure and control strategies of hybrid solid gravity energy storage system

Hybrid energy storage is an interesting trend in energy storage technology. In this paper, we propose a hybrid solid gravity energy storage system (HGES), which realizes the complementary advantages of energy-based energy storage (gravity energy storage) and power-based energy storage (e.g., supercapacitor) and has a promising future application. First, we investigate various possible system structure schemes for the proposed HGES. In particular, we also obtained two superior system structure approaches through comparative analysis for two typical application scenarios, distribution and transmission grids. Subsequently, we theoretically analyze and mathematically model the energy conversion relationship of HGES based on different subsystems. More specifically, we discuss the control strategies of HGES in detail at three levels: power electronics, single-type energy storage system, and hybrid energy storage system. In addition, we propose complementary capacity configuration schemes for power-based energy storage systems based on the control strategies. Finally, the proposed HGES structures, control strategies, and capacity configuration schemes for distribution and transmission grid scale are simulated and verified based on MATLAB/Simulink. The results show that the proposed hybrid energy storage system has the advantages of both energy-based and power-based energy storage, which significantly improved compared to single energy storage technologies.