The Dynamic Multi-objective Optimal Dispatch Of Combined Cooling,Heating And Power Micro Grid System

The combined cooling,heating and power(CCHP)micro grid system is an ideal micro grid system,which has the characteristics of energy step utilization and combines other distributed generation units.It has the characteristics of various operation mode,high-energy efficiency,flexible control,high reliability and small environmental pollution.Therefore,it has become a key research object of the second generation of energy technology and has attracted the extensive attention of countries around the world.In this paper,we mainly studied the multi-objective optimal dispatching strategy of the CCHP micro grid.Firstly,the composition models of the CCHP micro grid are introduced and analyzed in detail.Then,the output of system controllable devices such as micro gas turbine,battery,thermal-storage tank are selected as optimization variables to establish the CCHP micro grid optimization mathematical model based on the Pareto dominating relationship with the goal of the minimum operating cost and the pollutant emissions control cost.The constraints including the models in the system and the process of operation are classified,and different solutions are given according to different kinds of constraints.A new multi-objective particle swarm optimization algorithm based on optimized particle is proposed after the advantages and disadvantages comparison of multi-objective genetic algorithm and particle swarm optimization algorithm.Finally,taking the daily energy supply in a residential area as an example,the paper presents the Pareto front of the optimal scheduling problem for the typical days in summer and winter.The operation strategies of the system according to the lowest operating cost and the minimum control cost of pollutant emission are analyzed.The dispatching strategy of the system is compared with operation mode of “power determined by heat”,“heat determined by power” and the time of use pricing in the typical day of summer.Research results show that the multi-objective dynamic optimization dispatching method of CCHP micro grid proposed in this paper not only can select the different dispatching schemes flexibly according to different targets,but also can further reduce the operating and environmental cost.Considering the demand side response of the shiftable load,the load can be optimized firstly.The paper sets a target load which is inversely proportional with the price,and a mathematical model of three kinds of shiftable load which include the disinfection cabinet,washing machine and water heater is set up.In order to make the load curve and the target load to be as similar as possible,the paper proposed a shift strategy which is called “quantitative determined by quotient” and “margin determined by remainder”.Then the multi objective day-ahead optimal dispatch problem of CCHP micro grid on the basis of the shifted load data is optimized and the optimal dispatch results show that the operating cost of the system can be further reduced.