To meet the flexible regulation demands of the new power system under the "dual-carbon" goal

it is imperative to develop economically efficient energy storage technologies. The pumped hydro compressed air energy storage (PH-CAES) system

which combines the advantages of high efficiency of pumped hydro storage and high energy density and wide regulation range of compressed air energy storage

has gradually gained popularity. This paper first elaborates on the working principle and technical characteristics of PH-CAES

and conducts a comparative analysis with other large-scale new physical energy storage technology routes. Secondly

based on the current research status of PH-CAES

this paper summarizes the research status of three key technologies on the basis of its working characteristics

namely

the optimization of PH-CAES reservoir site selection

the reliable storage of water and air in the co-capacitance chamber

and the efficient operation of liquid pistons. Finally

in light of the current research status of PH-CAES and the future development trend of the new power system

this paper introduces the research focus from following three aspects: site planning

optimization design of the full working condition process

and operation control technology

providing reference value for future research on PH-CAES.