The Optimal Strategy For CCHP Multi-Energy Complementary System Considering Flexible Load

Within the increasingly serious environmental problems,improving the energy utilization,saving energy and reducing the emission of pollution has become a direction for smart grid,to which distributed energy resource connected to the grid and the development of microgrid control technology and active distribution network provides a solution.The distributed Combined Cooling Heating and Power(CCHP)system becomes a promising distributed energy resource with its high energy efficiency and stable power quality,which has been widely studied and applied.In this paper,firstly the traditional CCHP structure is optimized,in which the fixed relationship between power supply and heating has been broken.The paper analyzes the different working mode of CCHP under different user requirements in detail.Then,the relationship between the capacities of different equipment in CCHP system is quantified by model analysis.According to the energy utilization rate,"power determined by the heat" mode is determined for the example to choose the appropriate equipment capacity for the CCHP system in the centralized energy supply area.Secondly,this paper analyzes the characteristics of the flexible load,and proposes different control methods for different load types for demand side management.Taking into account the advantages of power supply side and demand side collaboration,the control strategy of CCHP and flexible load participating in global optimization of active distribution network is proposed,in which the optimized CCHP structure is used to make primary energy fully utilized while responding to the commands of active distribution network.The simulation results show that the proposed control method is superior to the traditional control method of CCHP.Finally,the CCHP multi-energy complementary optimization method considering the flexible load is proposed for microgrid control.The method considered many indicators including the economic factor,the environmental factor,the energy efficiency factor and the interests of users.The control method combines the supply side and the demand side together,and transforms the multi-objective optimization problem into an integrated single objective problem by analytic hierarchy process.However,the objective function is limited by many variables and multiple constraints,so the fitness function is constructed by penalty function method and solved by particle swarm optimization.At last the simulation example of the optimization method and traditional CCHP in microgrid control mode is compared,results show that the method can bring about 8.6% saving of daily expenses,and 7% reduction in greenhouse gas emissions and also can increase 5.6% local consumption capacity of renewable intermittent energy with high energy utilization efficiency.The research of CCHP and flexible load provides an effective and feasible solution for the application of microgrid and active distribution network control.