Methodology Research On Multi-energy Complementary Distributed Energy System Planning Based On Energy Hub Modeling

In the context of climate change and the goal of carbon peaking and carbon neutrality,it has become an inevitable choice for the sustainable development of society to further promote the energy revolution.Centralized and distributed energy systems are the trend and direction of energy system transformation.Developing distributed energy systems is of great significance for establishing multiple energy supply systems and ensuring national energy security.With the development of renewable energy technology and the concern of environmental governance,multienergy complementarity has gradually become the key direction of distributed energy system development in the future.Complicated advanced energy technologies are integrated into the multi-energy complementary distributed energy system(MCDES),in which the external boundary is complex and changeable.It makes the MCDES with the basic characteristics of multi-energy coupling and dual complementary connotations of "time scale" and "energy taste".However,given the optimal performance of the system under all working conditions,these characteristics bring severe challenges to the scientific and effective planning of MCDES.Some problems need to be solved urgently,such as multi-heterogeneous energy flow decoupling and fine system modeling.quantitative analysis of multiple uncertain factors,deep collaborative coupling of processes,multi-party game goal balance,coordinated planning of centralized and decentralized stations and networks,and efficient solution of planning problems.Based on the energy hub,combined with the theories and methods of thermodynamics,operational research,economics,graph theory,process integration,machine learning and uncertainty analysis,a preliminary exploration and research on the theory and method of multi-energy complementary distributed energy system planning are presented.Firstly,the general architecture and general planning criteria of MCDES are proposed.Based on the energy hub model,the concepts of the node of energy hub(NEH)and energy flow layer(EFL)are defined,and an extended energy hub(EEH)model suitable for multi-energy flow decoupling and fine modeling is constructed.Combined with the process integration method,the energy hub and its standardized modeling method are further developed.With the help of the bilevel programming concept of economics.multi-objective optimization of operational research and cluster analysis method of machine learning.a multi-objective and multi-period bilevel programming framework of MCDES is proposed to optimize system configuration and operation strategy simultaneously,and a method based on global sensitivity analysis to quantitatively study the influence of uncertain factors is constructed.It aims to provide theoretical guidance and methodological reference for the overall research.Secondly,based on an extended energy hub and bi-level planning framework,considering the off-design characteristics and the synergistic effect of energy equipment,the planning research of MCDES driven by fossil fuels is carried out.Based on the concept of NEH and EFL,the mathematical model of the equipment unit is constructed,and the mixed integer nonlinear programming model is formed with the economic objective.A corresponding two-stage evolutionary algorithm is developed:the top layer optimizes the system structure and equipment capacity through the multivariate heterotopic adaptive evolutionary algorithm,and the bottom layer optimizes the operation scheduling strategy through the interior point method.The influence of the off-design performance of the equipment on energy system planning is discussed through a case study.Thirdly,focusing on the multi-energy complementary distributed energy system driven by fossil energy,the planning research considering the influence of multiple uncertainties is carried out.The nonlinear factors in the MCDES planning model are eliminated by the linearization method,and the mixed integer linear programming model is constructed to improve the solving efficiency and the applicability of uncertainty analysis.A two-stage global sensitivity analysis(GSA)method is proposed in detail:the key uncertain parameters are discriminated by the elementary effect method to reduce the scale of the problem at first;then the key uncertain parameters are quantified and sorted by a variance-based GSA and Monte Carlo simulation method.On the basis of the scenario analysis,a case study is carried out to analyze the influence of off-design characteristics and demand side response on system planning,and to quantitatively analyze the uncertain factors that have a significant impact on the system economy.Then,the multi-objective planning of MCDES considering thermal integration and process synergy is studied.An MCDES driven by renewable energies is proposed.Based on the improved EEH,the energy system is modeled by the logic of "energy hub node-energy carrier-energy flow layer-temperature interval".Under the framework of bilevel planning,a multi-period and multi-objective programming model is developed based on typical daily analysis,augmented ε-constraint method and technique for order preference by similarity to ideal solution.The Pareto frontier and optimal allocation schemes are obtained in terms of economy,carbon emission and fossil energy consumption objectives.The influence of thermal integration,process coordination and energy storage capacity constraints on system configuration is compared and analyzed through case studies.Finally,the MCDES driven by renewable energy is taken as the research object.and the collaborative planning of stations and networks with the centralized arrangement of energy stations and decentralized arrangement of terminal consumption centers in the overall planning area is carried out.Based on geographical information system technology and graph theory,the regional energy system is abstracted into an energy network composed of nodes of terminal load centers,alternative addresses of energy stations,and road intersections.By describing the energy balance of the global nodes of the energy network and the energy and quality balance of the local energy hub within the nodes,a collaborative planning model of regional stations and networks is constructed.In this paper,the regional energy system of a university is planned and studied with the obj ectives of economy,carbon emission and fossil energy consumption,respectively.The differences in comprehensive energy efficiency and indexes of the system under different planning schemes are discussed.Moreover,the site selection of energy stations,regional heating/cooling pipeline network layout,energy station and terminal energy technology configuration under different optimization objectives are deeply analyzed.Within the double complementary connotation of "time scale" and "energy level”,based on the concept of energy hub and multidisciplinary theoretical methods,this paper preliminarily explores and develops the planning theory and method of MCDES based on EEH modeling,aiming at solving the key challenges faced by MCDES planning.According to the guidance of planning theory and method,combined with the MCDES driven by fossil fuels and renewable energies,the detailed modeling,uncertainty analysis,deep process coordination,multi-objective optimization,and station network coordination optimization were systematically studied,aiming at providing a guideline and support for the development and application of MCDES.