| Environment pollution and energy crisis have promoted the research of optimal planning and operation of a multi-energy system including the power system,natural gas system and heat system concerned.An energy hub which accommodates various forms of energy sources and different types of loads is an important part of a multi-energy system and the optimal configuration of the type and capacity of its devices is the basis for ensuring its secure and economic operation.Furthermore,the continuous development of demand response mechanism and technology imposes new requirements for this optimal configuration.On the other hand,due to the diversification of application scenarios,an effective comprehensive benefit evaluation method for the energy hub is needed to analyze the applicable scenarios and investment returns.Given the above background,some relevant research work is carried out in this thesis and summarized as follows.1)The framework of an energy hub and the model of integrated demand response(IDR)are developed.First,a complete optimal design routine for a basic energy hub framework is presented,followed by the introduction and mathematical models of typical devices in an energy hub,including energy production,conversion and storage equipment.Meanwhile,the detailed IDR model is proposed from the perspectives of the load response characteristics.The cooling,heating and power loads are classified into inflexible,shiftable and transferable ones respectively and their mathematical models are proposed considering their characteristics.2)An optimal configuration model of an energy hub considering integrated demand response is proposed.Based on the load curves in typical days,an 0-1 mixed-integer linear programming model is presented with an objective of minimizing the sum of the annual installation cost,operating and maintenance cost and energy consumption cost,while taking integrated demand response and operation constraints of an energy hub into account.A residential quarter is employed to demonstrate the feasibility and effectiveness of the proposed optimal configuration model,and the influence of the IDR on optimal operation is analyzed together with the sensitivity analysis of the cost to the thermal comfort and the participation degree of controllable power demands.Case studies demonstrate that,based on the proposed model,the annual operational expense of an energy hub significantly reduced.3)A comprehensive benefit index system and evaluation method for an energy hub is proposed.Based on the comprehensive analysis of the characteristics of the energy hub,an index system including economics,energy saving,environmental friendliness is developed with the traditional separate power(SP)system as the reference.Meanwhile,to avoid the disadvantages of different weighting methods,a comprehensive evaluation method is proposed to integrate the evaluation indexes.The scores of the indexes are calculated by the well-established extreme value method,and the index weights are divided into subjective and objective ones which are determined by the G1 method,an extended version of the well-known Analytic Hierarchy Process(AHP)method,combined with the fuzzy clustering method and improved entropy method respectively.Following the minimum identification information principle,the comprehensive weights can be determined and hence the final assessment results attained by the weighted average value of index scores.Finally,energy hubs of three types buildings(hotel,office building,residential building)in three representative cities(Beijing,Hangzhou,Shanghai)are optimized and the comprehensive binefits are evaluated compared with the SP system.The results show that climate condition and building type have a significant impact on system performance;an energy hub with more heating demand,lower load fluctuation and higher matching degree of cold-heat-to-power rate between the source and load can achieve better performance.Finally,the research work is summarized and future research prospects in this filed are pointed out. |
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