Study On Optimal Scheduling Of Integrated Energy System Considering Flexible Load Based On NNC Method

Contemporary human science and technology level is in a rapid development stage,energy scarcity and environmental governance issues have become the key factors restricting the development of energy strategies in the world,so the focus of future development of countries has been to advocate energy conservation and environmental protection.Our country is on the path of sustainable development,and traditional centralized energy supply is difficult to meet the requirements.Combined Cooling Heating and Power supply(CCHP)integrated energy system with the high energy conversion efficiency,The system can flexibly regulate the three kinds of energy,hot and cold,to meet the supply problems of different forms of energy.At the same time,renewable energy is involved in the energy supply,so that the system is more environmentally friendly,but also can effectively combine with the flexible load to achieve better results.The system is playing an increasingly important role in the energy field.This paper firstly summarizes the research and development status of integrated energy system and multi-objective problem processing at home and abroad,and then introduces the structure of cold,heat and electricity combined power supply system and energy supply side and demand side equipment,and establishes the corresponding mathematical models according to the operation characteristics of different equipment.Including wind energy,photovoltaic renewable energy;Controllable distributed power supply such as gas turbine,ground source heat pump;Such as absorption refrigerating machine,waste heat boiler;Energy storage devices such as batteries,heat storage tanks and ice storage equipment.It provides the theoretical basis for establishing the mathematical model of optimal scheduling.Secondly,the structure of the Combined heat and power supply(CHP)type integrated energy system is analyzed,and then the appropriate mathematical models of shifting load,shifting load and reducing load are established by taking the electrical flexible load as an example.Then the carbon trading mechanism is introduced and the constraints of each unit model of the system are specified.The optimal scheduling model is established by considering the operating cost and carbon trading cost of the system comprehensively.By comparing the optimal scheduling results under different scenarios,it is concluded that the participation of flexible load in the economic optimal scheduling of the system can not only adjust the load,but also achieve the purpose of peak shifting and valley filling.In addition,it can also reduce the total operation cost of the system,achieve the goal of low carbon economic dispatch of cogeneration integrated energy system,and also provide a certain reference value for introducing flexible load to study the flexibility and economy of the system.Finally,the flexible load model is introduced to introduce the flexible supply and demand balance.Aiming at the uncertain influence of renewable energy and load fluctuations on the operation of cold,hot and electricity combined integrated energy system,and considering the multi-energy complementarity between cold,hot and electricity supply and demand,a method is proposed to construct the flexibility evaluation index by calling a variety of flexible resources on the energy supply side and the demand side.Based on the balance of cold,thermal and electric power and the operating conditions met by each device,the multi-objective optimal scheduling model established in this chapter contains two objectives,namely,system operation economy and system flexibility.CPLEX solver is called by Matlab software to solve the established model.By introducing Normalized normal constraint method(NNC),a uniform Pareto front is obtained,which lays a good foundation for obtaining the optimal solution.By comparing the results of other multi-objective problems,the superiority of the normalized normal constraint method in dealing with this kind of problems is proved,and the use of this method has certain reference significance for the economic optimization scheduling of the integrated energy system.