Research And Optimization On The Heat-power Integrated Peak-shaving Technology In Coal-fired Thermal Power Plant To Reduce Wind Power Curtailment

The problem of thermal-electric coupling in coal-fired combined heat and power(CHP)system as well as the increasing heating demand on the user side limits its thermoelectric peak-shaving ability,which is the main factor causing the frequent problem of "wind power curtailment" in the heating season in the northern China.This thesis comprehensively considers the problems of waste heat recovery in circulating water and peak shaving in thermal power plants,and proposes an integration of heat and power peak-shaving(IHPP)system based on electric heat pump(EHP)waste heat recovery system combined with centralized thermal energy storage(TES)system.While improving the capacity of wind power consumption,it also creates certain economic and environmental benefits,and provides new mentality for promoting CHP to participate in wind power peak shaving.Firstly,based on the establishment a variable operating model of the unit's thermal system and the EHP heating system,the thesis studies the thermal-electric decoupling effect,coal consumption characteristics,and related influencing factors of the CHP unit coupled electric heat pump for heating under the variable operating conditions.The results reveal that the addition of the heat pump waste heat recovery system is beneficial to promoting the thermal-electric coupling of the unit and producing coal-saving effects,while the heating efficiency and heating capacity of the heat pump will have an impact on the above aspects.Meanwhile,the operation effect of the two heat recovery methods(adopting the EHP and adopting the absorption heat pump(AHP))in the peak-shaving scene of participating power plants are compared.It is found that the system coupled with the EHP is superior to that of the AHP in peak-shaving performance and energy saving.Subsequently,this thesis comprehensively considers the operation characteristics of TES and EHP,and further proposes the IHPP system which adopts the combined auxiliary units for heating.In addition,on the basis of the graphical method,the qualitative comparison of the overall heat and power output range of the combined heat and power system is conducted when the EHP and the TES are configured separately and when both of them are applied together.The conclusion proves that the latter has obvious advantages in peak-shaving flexibility,which can better adapt to the changing load demand on the grid side after wind power is connected to the grid.Then,according to the characteristics of regional grid's wind curtailment as well as the structure of power supply,a dynamic operation model of the integration of the IHPP system is established to simulate the operation of the system in the dispatch mode for the purpose of the wind power consumption.The results indicate that the IHPP system improves the level of wind power consumption and reduces the energy consumption of traditional electricity and heat sources.From the perspective of the heat source category,the heat supply of the EHP waste heat recovery system is stable and increases the power load of the power plant,which improves the heat supply efficiency of the unit,and is superior to TES in aspects of wind utilization capacity and energy saving.While from the perspective of configuration selection,the size of the heat source capacity is positively correlated with its capacity to the wind utilization capacity.Moreover,the greater the capacity of the EHP is,the lower the system energy consumption level is.However,if the selection unit of TES is too large,it will have side effects on the system energy saving effect;from the perspective of the dispatching mode,the power sale revenue of the thermal power plant can be improved,through adjusting the operation strategy in TES's period of heat storage and heat release to adapt to changes in the peak shaving demand of the power grid.Finally,by considering the operating profit of each unit,the maximum comprehensive profit in the heating season of the unified interests,which includes the thermal power plants,traditional thermal power plants as well as wind power farms,are set as the optimal goals to optimize the IHPPS system's design.The results show that the optimization method can realize the optimization of the operation strategy and auxiliary heat source configuration of the IHPP system when it participates in the abandonment of wind in the medium and long-term scale.