Optimal Operation Of Micro Energy Networks Based On Energy Hub Model

Energy plays an essential role in all social and economic activities with deep engagement.Energy cost is one of the key-driven factors contributing to industry manufactory and even other social areas such as culture and politics.Energy security and environmental issues have facilitated human beings to explore energy-efficient,economical and environment-friendly models.The energy network,combining various different energy categories,tends to be an innovative solution that attracts scientists’ eyeball worldwide.Such energy network helps to enhance reliability,reduce environmental pollution,facilitate technology development in the energy system and promote energy sustainability.Hereby energy hub(EH)can be used to build up energy network model.In terms of micro energy network(MEN),the multi-energy network operation optimization is analyzed based on the EH model.The solution is applied to the regions with highly intensive energy consumption,including residential areas,urban areas,etc.Besides,the rapid urbanization has led to load volume expansion and diversified energy consumption.The advanced technology of renewables integration,alongside with storage and conversion sections,has improved energy efficiency.The new research proposal is required to optimize EH structure and operations of MEN model built up by multiple EH.This dissertation especially aims to resolve the following key issues:1/ This thesis presents an extended EH model to optimize total energy use costs for loads in residential areas,with the aim to fulfill the research gap in EH modeling and improving the operational efficiency of multiple forms of energy consumption.This extended model considering the involves solar energy(provided by PV and SHE)combined with Battery energy storage system(BESS).The optimization problem is set up based on daily load demand(such as electricity,heat,and cooling)and time-of-use(TOU)energy prices.A mathematical model is constructed with the objective of optimizing total energy cost during the day,including some constraints such as input-output energy balance of the EH,electricity price,capacity limitation of the system,and charge/discharge power of BESS.Four operational cases based on different EH structures are compared to assess the effect of solar energy applications and BESS on operational efficiency.The results show that the proposed model predicts significant changes to the characteristics of electricity and gas power bought from utilities,leading to reduced total energy cost compared to other cases.They also indicate that the model is appropriate for the characteristics of residential loads.2/ The structural and optimal operation of an energy hub has a tremendous influence on the hub’s performance and reliability.In order to achieve the global optimum conditions for supplying energy,it is quite essential to develop the optimization research issues by focusing on hub system structure and operation simultaneously.Based on the lack of study about joint optimization problem,this research also concentrates on establishing a mathematical model to rapidly identify the optimal model structure that simultaneously satisfies two objectives: optimizing operating costs and selecting the optimal operating structure.The objective of the investigation is to penetrate into this joint optimization problem with a handy calculation method.This thesis envisions an innovative methodology that prominently increases the synergy between structural and operational optimization and targets system cost affordability.The generalized energy system structure is presented theoretically with all selective hub submodules,including electric heater(EHe)and solar sources block sub-modules.To minimize energy usage cost,an energy hub is proposed that consists of 12 kinds of elements(i.e.,energy resources,conversion,and storage functions)and is modeled mathematically in a General Algebraic Modeling System(GAMS),which indicates the optimal hub structure’s corresponding elements with binary variables(0,1).Simulation results contrast with 144 various scenarios established in all 144 categories of hub structures,in which for each scenario the corresponding optimal operation cost is previously calculated.These case studies demonstrate the effectiveness of the suggested model and methodology.3/ Previous peer research seldom addresses the problem of multiple EH optimal operations.Considering integration of renewables and storage systems,the dissertation proposes a method to coordinate optimal operations in MEN containing electricity and natural gas networks,based on EH model.The EH can be considered as the grand network node to contain various categories of energy.The demands for electricity,heat,and cooling load can be fulfilled with the application of conversion and storage devices.Four different operating scenarios are established to evaluate how energy sources and storage systems influence MEN.In comparison to traditional electricity supply,the simulation results indicate that MEN built up by EH,with the integration of solar energy,wind energy and storage systems,is more efficient.The General Algebraic Modeling System(GAMS)is applied to solve the optimal operating problems in this study.The dissertation research contributes to the modeling and calculation for flexible and efficient energy management,meeting the demand for small-scale loads with various energy engagement.