[Objective

]

Under the “dual-carbon” strategic targets and the accelerating integration of high-proportion renewable energy into the grid

coal-fired cogeneration units face increasingly severe challenges in operational flexibility

especially during the heating season. Such units are typically constrained by the “heat-led-electricity” mode

where the minimum power output is dictated by the heating demand

severely limiting their ability to participate in peak-shaving and accommodate intermittent renewables like wind and solar. To address this issue

this study proposes a thermoelectric decoupling scheme based on a fluidized-bed high-temperature particle thermal energy storage(TES) system. The aim is to decouple the traditionally coupled electricity and heat outputs

thereby enhancing the independent regulation capability of both electric and th

ermal loads while ensuring reliable district heating supply. [Methods

]

A 315 MW subcritical coal-fired cogeneration unit is taken as the research object. A steady-state thermodynamic model integrating the power unit with a fluidized-bed particle TES system is developed using the professional simulation software Ebsilon. The TES system operates on a “store electricity during off-peak

supply heat during peak demand” strategy. During periods of low grid load or high renewable generation

surplus electrical energy is converted into thermal energy by heating quartz-sand particles to 800 ℃ in a fluidized-bed electric heater; the hot particles are then stored in an insulated tank. During peak power demand or high heating requirement

the stored thermal energy is released via a fluidized-bed heat exchanger to heat the district-water return flow

thereby supplying additional heat without extracting more steam from the turbine. Key performance indicators

including the equivalent additional extraction steam flow(ΔD

max

)

the heating safety zone

the heat-supply decoupling capacity

and the peak-shaving decoupling capacity

are defined and quantified to evaluate the system's decoupling performance. Furthermore

a typical winter day scenario with high renewable energy penetration is constructed to assess the practical electricity-heat coordinated operation capability. [Results

]

Simulation results demonstrate that the integration of the fluidized-bed TES system significantly expands the operational heating safety zone of the unit. The system provides an equivalent additional extraction steam flow of 15.62 t/h during the heat storage process and 96.33 t/h during the heat release process. This enhancement substantially improves the unit's heat-supply decoupling capacity under low-load conditions and increases its peak-shaving range when the heating demand is high. In the typical high-renewables day scenario

the coupled system enables the unit to better follow the fluctuating grid load instructions while maintaining

the required heating supply. The mismatch between the actual heat load and the unit's heating capability is significantly reduced compared with the original operation. [Conclusion

]

The fluidized-bed high-temperature particle TES technology can effectively achieve thermoelectric decoupling in coal-fired cogeneration units

significantly enhancing the flexibility and heating assurance. It offers a feasible pathway for flexibility retrofitting of existing units and for promoting the accommodation of renewable energy.