## 1 Introduction  
To address the adverse impacts of climate change, clean energy such as solar energy, wind energy, and hydropower is gradually accelerating the pace of replacing traditional fossil energy [1]. However, restrictions and technical barriers still exist, constraining the development of clean energy. Clean energy power generation is unstable, intermittent, unpredictable, etc., which requires that it be combined with thermal power units to improve the peak regulation ability. However, long-term operation under off-design conditions will cause great damage to thermal power units, and the peak periods of consumer electric power consumption and clean energy power are inconsistent. In order to handle these issues, developing energy storage system (ESS) technology is vital to guarantee the development of clean energy [2]. At present, the pumped hydro energy storage system (PHS), the electrochemical energy storage system, the compressed air energy storage system (CAES), and the thermal energy storage system (TES) are the main mature energy storage technologies. Among them, the PHS is the most extensively applied [3] for its superiority in its long lifetime, mature technologies, and low investment cost compared to battery and thermal energy storage systems [4; 5]. However, it needs to equip upstream and downstream reservoirs, which requires suitable geographical conditions and long-period construction, making for an unignorable influence on regional ecology. Electrochemical energy storage realizes the energy conversion between chemical energy and electricity through chemical reactions. And it has received much attention from scholars due to the advantages of its short energy transition time, flexible site selection, and capacity configuration. However, it also has a great disadvantage in large capital investment [6]. TES technology is often combined with other energy storage systems to improve the energy utilization and avoid the usage of fuel, which benefits both the environment and the construction cost. It stores the thermal energy in sensible, latent, and thermochemical forms [7]. It has three mature classifications [8]: sensible thermal energy storage (STES), latent thermal energy storage (LTES), and thermochemical energy storage (TCES). Specifically, STES often works at low-mid-range temperature conditions [9], and the storage mediums typically used are water, oil, sand, molten salts, and some inorganic liquids [10]. As to the medium of STES, molten salt is usually applied in the Solar Power Industry for its favorable heat transfer characteristics in the mid-high temperature range, and unsaturated water is also a preferred medium for its low cost [8]. STES stores the thermal energy by increasing the temperature of the storage medium to store the sensible heat. [PERSON] et al. [11] compared the thermal and economic performances of different kinds of TES technologies, considering that STES is the only cost-effective technology, especially for mid-high-temperature industrial applications. [PERSON] et al. [12] compared the thermal performances of the LTES system (where the storage medium is paraffin RT55) and STES system (where the storage medium is water), finding that water could make the thermal storage capacity more efficient than paraffin. Other scholars have also paid attention to the combination of TES and different forms of heat in coupling systems. [PERSON] et al. [13] utilized a TES unit to store the thermal energy during the compression stage and release it during the expansion stage, realizing the high cycle efficiency of an adiabatic-CAES plant. [PERSON] et al. [14] employed a TES to store the released heat from the compression process and the heat transferred by electrical heaters from wind farm power. The dynamic simulation under steady wind power generation and real conditions were both conducted, and the results showed that the RTE reached 57.55% and the energy density reached 84.1 kWh/m\({}^{3}\). Compared to other grand-scale energy storage systems, CAES has been studied widely [15].