Abstract: To enhance the grid-connected safety of electrochemical energy storage plants and support refined power grid simulation, a unit-plant level unified two-level electromechanical transient simulation model is established in accordance with relevant national standards. The comparison and verification results between simulation outputs and measured data indicate that the proposed model and its key parameters can accurately characterize the operating characteristics of electrochemical energy storage plants, which thus provides insights and guidance for the development of power station modeling work.