Abstract: To enhance the peak-shaving capability of power systems with a high proportion of renewable energy, this paper focuses on the flexible retrofitting of thermal power units and develops a model for the electricity-to-heat conversion process in a Carnot battery coupled with a heat pump and electric heating. The thermodynamic performance of the system under different coupling configurations is investigated. A steady-state thermodynamic model of an air working fluid reverse Brayton cycle is established using Aspen HYSYS. The operating characteristics and performance differences of two coupling types—series and parallel—are systematically analyzed. In the series configuration, three arrangements of the electric heater are studied: placed before the compressor, after the compressor, and after the heat exchanger. The results show that in the system without recuperation, the optimal performance is achieved when the electric heater is located after the compressor, with a maximum coefficient of performance (COP) of 2.065. In the recuperated system, the optimal configuration occurs when the electric heater is placed after the molten salt heat exchanger, yielding a maximum COP of 1.292. Furthermore, two parallel system models are developed: a dual heat pump parallel system and a heat pump–electric heater parallel system. The results indicate that the dual heat pump system provides higher heat output under rated load conditions, whereas the heat pump–electric heater parallel system exhibits a more significant improvement in energy efficiency under part-load conditions—the COP increases from 1.182 to 1.230 as input power decreases—demonstrating excellent operational flexibility. Comprehensive analysis reveals that the coupling configuration between electric heating and the heat pump significantly influences energy-grade matching and system efficiency: tight coupling enhances synergistic performance, while decoupled designs help maintain stable and efficient operation in complex systems. This study elucidates the key mechanisms and optimization pathways of heat pump–electric heating synergy, providing theoretical support for the flexible retrofitting of thermal power units and the engineering application of Carnot battery energy storage systems.

Key words: Carnot battery, heat pump, electric heating, coupling model, thermodynamic analysis