Comprehensive economic analysis of deep peak shaving in thermal power-heat storage coupling systems
The integration of thermal power plants with heat storage technology can enhance the decoupling capability of the units,thereby reducing the impact of deep peak shaving on the safety and economic viability of the system.This study proposes a coupled system comprising thermal power plants and packed-bed heat storage.Considering the dynamic time series of unit variable operating conditions and packed-bed heat storage/release processes,a simulation model of the coupling system under variable operating conditions was established using Ebsilon.We analyzed the impact of deep peak shaving on the thermal dynamics and carbon emissions of the coupling system.The effect of deep peak shaving on the boiler's life loss rate was investigated by calculating the stress variation of the steam-water separator cylinder.The impact of deep peak shaving on turbine consumption was also examined by analyzing the rotor life loss rate curve.Consequently,an efficient model for the scheduling operation of the coupling system was established to conduct a comprehensive economic analysis.The results show that when the boiler operating status and system power generation remain constant and the power supply structure comprises a renewable energy and energy storage ratio of 5∶1,the coupling system reduces carbon emissions by 7418 t/a(with only wind power)to 9216 t/a(with only photovoltaics)compared with self-variable conditions.The impact of deep peak shaving on the boiler lifespan loss is greater than that on the turbine;however,the coupling system can improve the system lifespan.With deep peak shaving occurring 318 times/a,it can increase by 13.3%—15.3% compared to the unit's self-variable conditions(30%—20% rated load).The economic benefits of deep peak shaving in the coupling system are greater than those of the thermal power plant's self-variable conditions.When the heat released by the packed bed is used for power generation or heating,the benefits of the coupling system increase by 400000 and 720000 RMB/year,respectively,compared to its self-variable conditions.
thermal power plantheat storagedeep peak shavingcomprehensive economic performancesystem service lifecarbon emissions
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