## 1 Introduction  
Under the pressure of the Paris Agreement, countries around the world have proposed carbon peaking and carbon-neutral targets to further implement their carbon emission reduction goals [1; 2; 3]. For the energy sector, the essence of carbon reduction is to reduce the use of fossil energy and replace it with low-carbon renewable energy [4; 5; 6]. However, renewable energy sources, e.g., wind power and photovoltaic, are directly dependent on natural energy sources, so the power generated has large intermittency [7; 8; 9]. Intermittent power exhibits high uncertainty and is difficult to accommodate in the system, resulting in the common phenomenon of wind and solar energy curtailment [10; 11; 12]. Energy storage is a good partner for renewable energy in practical applications because it can be flexibly charged and discharged like an energy sponge, showing better flexibility [5; 13]. Therefore, energy storage planning for systems containing renewable energy has become an international study hotspot in the field. With the widespread adoption of renewable energy and the development of energy storage technologies, energy storage planning in source-side centralized renewable energy plants has been well studied. [PERSON] et al. [14] proposed a gravity energy storage system tailored for mountainous regions and developed an optimal capacity planning model for an on-grid wind-photovoltaic-storage hybrid power system. [PERSON] et al. [15] employed an optimal combined capacity planning and scheduling model to investigate the economic feasibility of using hydrogen and ammonia for islanded renewable energy storage. [PERSON] et al. [16] introduced an innovative co-planning model encompassing wind farms, energy storage, and transmission network, accounting for imbalanced power, unit ramp capacity, and renewable energy incentives. [PERSON] et al. [17] focused on the grid-connection transmission line and locally deployed energy storage unit capacities in conjunction with solar plants, exploring the feasible set of capacities. Furthermore, solar thermal storage has gained increasing attention in recent years. [PERSON] et al. [18] demonstrated the practicality of integrating thermal storage into renewable power generation systems, highlighting its ability to fulfill 100% of energy requirements and alleviate the demand for more hazardous alternatives. [PERSON] et al. [19] proposed a two-stage decision-making framework for wind and concentrating solar power energy systems, investigating thermal energy storage capacity planning and energy dispatch. Simultaneously, demand response is gaining more and more attention in the context of increasing uncertainties in the power system. Demand-side energy storage (DES) is the fundamental guarantee to enhance demand response capability and improve load elasticity. Promoting demand-side energy storage planning is both a realistic development need and a way to ease the pressure on electric power companies to invest in energy storage. [PERSON] et al. [20] developed an integrated model for power generation and customer-sited energy storage system expansion planning, examining the impact of customer-sited energy storage systems on the integration of renewable energy. [PERSON] et al. [21] formulated a storage capacity expansion planning model incorporating multiple functions of hybrid energy storage within regional integrated energy systems. They further proposed an operational strategy for hybrid energy storage to actively participate in demand response activities. [PERSON] et al. [22] focused on multi-energy coupling demand response and presented an optimization method for energy storage in microgrids. User-side scenarios are more diverse and relatively blank in research, so demand-side energy storage planning research will be a promising research direction. The development of demand-side energy storage cannot be achieved without the participation and investment of users or agents.