Heat-power peak shaving and wind power accommodation of combined heat and power plant with thermal energy storage and electric heat pump

Wind power curtailment becomes a major problem in many countries. The wind accommodation mechanisms and energy saving potentials for the combined heat and power plant with thermal energy storage, electric heat pump and both should be evaluated more systematically and accurately to accommodate more wind power. Heat-power peak shaving capacities for thermal energy storage, electric heat pump and both are analyzed using a graphical method, while the operation strategy is proposed to maximize wind accommodation. A simulation model for wind power accommodation considering the energy balances and constraints of all production units is developed based on EnergyPRO. A regional energy supply system in Jilin Province, China is selected as the case study, where the influences of different peak shaving technologies and their parameters on the wind accom-modation and energy saving are studied. The wind curtailment ratio is reduced from 20.31% to 13.04% and 7.51% with thermal energy storage and electric heat pump respectively, and it is further reduced to 4.21% with both. Systems with electric heat pump can save energy from 1.1% to 5.8% with different parameters of the peak shaving devices. It was found that electric heat pump has better accommodation capability than that of thermal energy storage. Wind accommodation can be improved by adding thermal energy storage to electric heat pump, but the effect gradually decreases as the storage size increases. Electric heat pump can increase the system's energy efficiency, but it is not always energy efficient by adding thermal energy storage to electric heat pump. In fact, thermal energy storage should not be too large, otherwise the system's energy efficiency will be reduced.

Automated summary

Wind power curtailment is a global issue, and a systematic and accurate evaluation of the wind accommodation mechanisms and energy saving potentials of thermal energy storage and electric heat pump is needed. In this study, it is found that electric heat pump has better wind accommodation capability and adding thermal energy storage can further improve wind accommodation, although the effect diminishes with storage size increase, based on a case study of the energy supply system in Jilin Province, China.