Research On Energy Efficiency Assessment And Operation Strategy Optimization Of Distributed Multi-Energy System

Under the background of energy revolution with emphasis on clean energy,low carbon and high efficiency,the distributed multi-energy system close to the terminal energy users can improve the comprehensive energy efficiency and achieve the goal of energy saving and emission reduction through the use of multiple energy sources,it has become one of the common concerns of all countries around the world.In order to accurately evaluate the overall energy utilization efficiency of a distributed multi-energy systems and improve the overall energy utilization efficiency of the system by optimizing the system operation strategy,the main research work is as follows:This thesis first establishes a variable operation conditions energy conversion model for distributed multi-energy systems.Taking a complementary multi-energy demonstration project in Shandong as an example,the energy supply structure of the distributed multi-energy system is analyzed,and the working characteristics of each device in the distributed multi-energy system is studied.On the basis of fully considering the characteristics of variable operation conditions,input and output energy conversion models are established under variable operating conditions for the following devices:gas internal combustion engine,flue gas type lithium bromide absorption chiller,ground source heat pump,air source heat pump,photovoltaic power generation,ice storage air-conditioning system and energy storage device,which can establish a model basis for system energy efficiency assessment and operational strategy optimization.Furthermore,an energy efficiency assessment model for distributed multi-energy systems is established.From the perspective of the system’s consumption of non-renewable energy,the absorption of renewable energy,and the degree of energy conversion within the system,this thesis establishes the energy efficiency evaluation indices for distributed multi-energy systems and proposes a multi-scenario comprehensive energy efficiency evaluation method based on information entropy.By analyzing load characteristics in actual case,five typical operating scenarios of the system are summarized,and the simulation of each typical scenario is carried out.The comprehensive energy efficiency assessment model established in this thesis can accurately calculate the quantitative values of energy efficiency indices and the weights of energy efficiency indicators in specific scenarios,the comprehensive energy efficiency quantitative values of energy efficiency indices in specific scenarios are calculated and the quantitative values of energy efficiency of the system throughout the year are estimated.Finally,the distributed multi-energy system operation strategy is optimized.Considering that the system operation strategy has a great impact on the overall energy efficiency of the system,in this thesis,the distributed multi-energy system operation optimization model is established with the objective function of minimizing consumption of non-renewable primary energy and minimizing system exergy input.Through simulation of the actual case,the time-based operation scheduling scheme of each energy-supply equipment under different typical operating scenarios is obtained,and comparing the values of the unoptimized and optimized energy efficiency indices,the results show that the comprehensive energy efficiency of the system is improved after optimization.Through the summarization of the distributed multi-energy system operation strategy,guidance and suggestions are put forward for system operation.Through the multi-scenario energy efficiency assessment method proposed in this thesis,it can provide theoretical basis and practical method for energy efficiency assessment and system scheme decision of distributed multi-energy system.By optimizing system operation strategy,it can provide a theoretical reference for the efficient operation of distributed multi-energy system.