Research On The Collaborative Integration And Active Regulation Methods For Combined Cooling,Heating,and Power Systems

As a leading technology in the field of energy reduction,combined cooling,heating,and power（CCHP）systems has great advantages over the traditional energy supply mode in energy savings,economical savings and carbon dioxide emissions reduction.Due to the multi-type,multi-climate and hourly fluctuation load demand of users,reasonable system integration design and off-design regulation methods are the key to improve the system performance.Therein,in this work,based on the energy matching performance between the CCHP systems load output and user requirement,and breaking through the traditional case studies,the load coupling and decoupling mechanism between systems and users are revealed,and the universal methods of collaborative integration and active regulation are obtained,respectively.In terms of the collaborative integration method:the load demand characteristic parameters that reflect the load demand amount and hourly fluctuation for users were extracted,and comprehensive mathematical models of the load demands of users in a typical dat were established based on the simplified square wave demands,and three categories CCHP users were categorised（L-user,T-user and Q-user）based on the time-related parameters.Meanwhile,according to the proposed dimensionless load-matching parameters,a load-matching map was drawn（including 9 energy-matching sub-regions）and 53 types load-matching relations for the three categories users were constructed based on two different capacity design methods.Then the system configuration design method under different energy-matching scenarios,the applicable situation for“priority to providing electricity”and“priority to providing thermal energy”capacity sizing schemes,energy savaing boundaries and the suitable users for CCHP systems were explicated,respectively.Meanwhile,from the point of ideal energy storage systems,thermal energy storage system（TESS）,electric energy storage system（EESS）,and hybrid energy storage system（HESS）were coupled with a conventional CCHP system,respectively,and the capacity sizing schemes and energy-matching performance for different system configurations are analysed quantitatively,and a performance comparison is conducted to select the most suitable energy storage coupling configurations for different climate zones of China.In terms of the active regulation method:Based on the energy-matching performance between the load demands of users and provision of CCHP systems,two operating strategies,following the electric load（FEL）and following the thermal load（FTL）strategies,were compared and analyzed and their suitable application scenarios were also calculated.Meanwhile,the optimal operation strategy（FOL）was proposed with the goal of achieving"self-sufficiency"of cooling load of the system.And based on the FEL,FTL,and FOL operation strategies,the comprehensive operation strategy map was drawn to guide systems running in the off-design condition,which were suitable for different energy-matching performance in ESR,CO₂ emission reduction（CO₂ER）,and operation cost reduction（Cost R）.Moreover,the essential difference between active and passive energy storage regulation method in different energy storage positions of the system was compared and analyzed,and the decoupling mechanism of energy storage on the cooling,heating and electric load of the system was revealed,and the active energy storage regulation method of the system coupled with medium temperature heat storage unit was proposed.Meanwhile,a composite phase change material with high energy storage density and high thermal conductivity was developed based on the actual heat storage/release characteristics of the medium temperature heat storage unit,and an experimental platform for medium temperature phase change energy storage with a heat storage capacity of 60～80 MJ was built to obtain experimental data of energy storage/release under different control parameters.A universal thermal resistance model for phase change energy storage was established,and the effects of design and control parameters on energy storage/release characteristics were also analyzed.Then two different kinds of phase change energy storage regulation methods,serial and parallel,were proposed.