With the implementation of the “dual carbon” strategic goals, the proportion of offshore renewable energy is gradually increasing, raising higher demands for the integration of renewable energy in coastal power systems. In this context, underwater compressed air energy storage (UWCAES) has emerged as one of the key technologies to address the challenges of high proportions of renewable energy in coastal areas, due to its advantages such as large capacity, zero carbon emissions, and stable operating conditions. This paper proposes a configuration strategy for UWCAES considering multi-level gas storage arrangements. Firstly, based on the spatial distribution characteristics of gas storage in shallow and deep underwater areas, a multi-level compressed air energy storage model is established to enhance the operational flexibility of UWCAES. Secondly, aiming to maximize system benefits, a configuration model for multi-level compressed air storage is proposed, which takes into account constraints related to the operation of multi-level compressed air and system power balance. Subsequently, a genetic algorithm is employed to determine the depth and capacity of gas storage in both shallow and deep water areas, facilitating rapid acquisition of configuration results. Finally, simulation cases validate the effectiveness of the proposed configuration strategy. Compared to UWCAES operating at a single gas storage pressure level, the proposed multi-level UWCAES significantly improves the grid’s capability for renewable energy absorption and economic performance. The multi-level gas storage arrangement effectively enhances the regulation performance and economic advantages of UWCAES under complex operating conditions, and provides a practical technical path for the storage planning of coastal power systems with high proportion of renewable energy.

Energy storage plays an important role in establishing a modern energy system with clean energy as the core. In the new power system, the energy storage technology is mainly applied to promote the consumption of new energy, participate in the auxiliary service of the power market and support the construction of grid-load storage system. Firstly, the structure and classification of energy storage are summarized, and the application characteristics of energy storage are introduced according to power side, grid side and user side respectively. Then, it discusses the way of energy storage promoting new energy consumption on the grid side, and introduces the technology of "electric hydrogen production" to promote new energy consumption. Secondly, the construction of grid-load storage and its typical projects are introduced. The diversification of source grid load storage subjects greatly promotes the development of new energy and realizes the maximization of energy utilization. Finally, the development of power auxiliary services at home and abroad and typical energy storage cases are summarized, and the future development trend of energy storage is prospected.