Research On The Optimal Planning And Operation Strategies For District Integrated Energy Networks

Multi-energy network whereby electricity,heating,cooling and storage optimally interact with each other at various levels is the core framework and physical carrier of Energy Internet,wherein tight interactions have always taken place and are increasing due to its complex nonlinear stochastic characteristics and many degrees of uncertainty.In this context,a key aspect to evolve toward a more stable and economical energy network is system-level optimal planning,energy management and dispatching,which further points out the emergency as well as importance of related theories,approaches and techniques to be solved.Based on the analysis and comparison of existing energy planning and analysis tools,this thesis focuses on the planning method and operation optimization strategy of district integrated energy networks,provides a holistic approach for load forecasting,location,network layout,integrated modeling and optimization of energy systems affecting network planning,design and operation.Multi-energy coupling and feedback mechanism as well as the dynamic interactions and energy scheduling between different subsystems are also investigated to form the time-coordinated optimal planning and operation strategy for multi-energy network tightly integrated in district integrated energy system.On this basis,designed for solving problems of existing industrial building energy-saving retrofitting,optimization of district distributed CCHP(Combined Cooling,Heating and Power)system,and planning and pipeline layout of large-scale integrated energy networks,three substantial and universally applicable MINLP(Mixed Integer Non-linear Programming)methodologies are modeled with actual case analysis,providing theoretical guidance and technical support for the planning and operation of the district integrated energy network.The main work is as follows:(1)A district integrated energy network planning and operation optimization method based on system configuration and decision-making is proposed,wherein the energy system configuration comprises load forecasting,energy conversion and dispatching,technical constraints,available local resources and other balance or constraints.The factors of system evaluation and decision-making are from a macro-view such as economic,environmental,energy efficiency and combined multi-criteria evaluation.(2)Representative district energy planning and analysis tools are selected for systematic analysis and comparison from the perspective of supply-side energy planning and demand-side energy consumption as well as typical application fields-urban energy system planning,building energy analysis,transportation energy planning,industrial energy analysis and power system analysis.(3)The MINLP optimization model of district integrated energy network is proposed,based on which the effect of building envelopes retrofit,technology performance and hourly operation strategy on energy network planning is investigated.A comprehensive evaluation framework based on entropy weight method is carrieed on system assessment in terms of technology,economy,environment and energy efficiency.The accuracy and reliability of the model are verified by real-world case study conducted in urban China.(4)An integrated optimization model for high-dimension and multi-energy systems with multi-functional building complexes characterized by various demands is presented.With all the demand of electricity,heating and cooling satisfied,the optimal technology combination and hourly operation strategy of traditional and renewable energy technologies are investigated coupling energy storage systems,taking into account the fluctuations in load demands that may be caused by district population growth and increased construction area.Besides,the hourly energy consumption and load growth rate during the planning period are also considered to reduce the excessive error due to average of loads,and the feasibility of the model is verified by simulation examples.(5)An optimization model for energy network layout planning and operation incorporating multiple sub-systems at district level is proposed,whereby the tradeoff between system siting,pipeline layout and energy dispatching that few studies involved is studied and synthetically improved considering time-varying and complementary load characteristics,and the impact of hourly transmission losses and equipment load on operating efficiency.Thereby to achieve integrated optimization of technology combination,location,pipeline layout,energy dispatching and operation strategy between the regions.Meanwhile,the layout planning and operation strategy of large-scale district energy networks under different optimization objectives are compared with case analysis.