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Pumped-storage hydropower plants can contribute to a better integration of intermittent renewable energy and to balance generation and demand in real time by providing rapid response generation. The utilisation of variable-speed pump-turbine units with a doubly fed induction machine is being progressively applied due to its overall efficiency and high level of operating flexibility. This study presents state-of-the-art pumped energy storage system technology and its AC–DC interface topology, modelling, simulation and control analysis. It also provides information on the existing global capacities, technological development, topologies and control strategies of the pumped-storage system. This report also outlines the analysis of dynamic performances of the system. It also attempts to recommend the future works in this area. This study concludes that pumped storage is the most suitable technology for small autonomous island grids and massive energy storage, where the energy efficiency of pumped storage varies in practice. Around the world, the size of the pumped-storage plant mostly lies in the range of a small size to 3060 MW. The back-to-back voltage source converter topology is mostly conducted due to its significant features. Due to its imperative features, the vector control strategy is widely used. The pumped-storage plant is dedicated to power management and stability regulation of grid and isolated power systems. [ABSTRACT FROM AUTHOR]

Modular Gravity Energy Storage (M-GES) systems are emerging as a pivotal solution for large-scale renewable energy storage, essential for advancing green energy initiatives. This study introduces innovative capacity configuration strategies for M-GES plants, namely Equal Capacity Configuration (EC) and Double-Rate Capacity Configuration (DR), tailored to optimize energy storage efficiency and stability. Through comprehensive MATLAB/Simulink simulations, we demonstrate each configuration's distinct power characteristics and operational advantages. Our findings reveal that while the EC configuration offers enhanced power accuracy and stability, it requires a larger number of units. In contrast, the DR configuration, characterized by fewer but larger units, shows a trade-off with reduced power stability. This paper contributes significantly to the field by presenting a first-of-its-kind comparative analysis of these configurations, offering insights into their practical applications and scalability. The proposed strategies and findings lay a foundation for future research and development in gravity energy storage systems, marking a step forward in pursuing sustainable and reliable energy solutions. [Display omitted] • Two typical unit capacity configuration strategies for M-GES power plants are proposed. • The unit scheduling method of the M-GES power plant is proposed. • The coordination control method is provided for each proposed configuration strategy. • Equal capacity configuration has better power accuracy but requires more units. • Double rate configuration needs fewer but larger units and less power stability. [ABSTRACT FROM AUTHOR]