Simulation And Coordinated Optimization Of Supply And Demand In Multi-Energy Systems

In the face of increasingly severe climate change,the Paris Agreement was signed in December 2015,ushering in a new era of clean,low-carbon and sustainable development.Under this background,in 2016,the National Development and Reform Commission and National Energy Administration pointed out that multi-energy complementarity and supply-demand coordination are of great significanceis for building a clean,low-carbon,safe and efficient energy system.The implementation of coordinated multi-energy project is listed as the main task of energy development during the 13th Five-Year Plan period.After Chinese President Xi Jinping proposed that "striving to peak carbon dioxide emissions by 2030 and achieve carbon neutrality by 2060" in September 2020,research and development of multi-energy coordinated energy system has been promoted to the height of the national strategy.Therefore,this thesis focuses on the key theory of multi-energy coordinated system,it studies the characteristics of supply and demand of the system,and puts forward the optimization method of distributed and centralized energy system based on the principle of supply demand coordination and multi-energy complementarity.The research results are of great significance to the transformation and upgrading of China's energy system and supporting the "2030 carbon peak and 2060 carbon neutral" strategic goal.The main research contents of this thesis are as follows:(1)The high-resulution simulation of energy demand and demand response(DR)strategy is studied.In this work,a multi-agent simulation framework for building energy demand and electric vehicle(EV)charging demand is established.Based on the heterogeneity of multi-agent,the states and behavior rules of occupant agents and multitype device agents are defined in a building model.The multi-energy demand simulation is realized based on environmental attributes and agent interaction.In the EV model,the user's travel pattern and charging pattern are defined by the trip chain method.The trip chain includes seven types of travel purposes and three types of locations,the spatial-temporal distribution of charging demand is simulated with uncontrolled and off-peak charging strategies.After this,the thesis studies two types of DR schemes.Under the price-based DR scheme,the energy saving potential of the building and of different types of electrical appliances related to the tiered pricing,peakvalley pricing and critical peak pricing mechanisms are calculated,which reflects the importance of users' energy saving behaviors.The charging and discharging flexibility of EVs are defined under plan-based DR scheme.To solve the discrete resource scheduling problem,a global optimization and decentralized control methods under discontinuous time series are proposed to achieve the optimal charge-discharge scheduling.(2)The modeling and optimization of distributed and centralized energy system are studied.In the distributed system study,the thesis considers load level-efficiency relevance,temperature-efficiency relevance,electrical-thermal efficiency correlation(operational feasible region)and the impacts of start-stop and ramping up of equipment in system modeling.The linearization method is used to develop the bilevel optimization framework for combined cooling,heating,and power(CCHP)system considering off-design characteristics.Then,the impacts of various off-design characteristics on system planning and hourly operation are analyzed while the energy demand of buildings and EVs is satisfied.For centralized system,the thesis develops a medium-term and long-term planning model based on the fast unit commitment(FUC)method.Electrolytic hydrogen production system optimization is integrated into the simulation of power system to estimate the economic and technological feasibility of power-to-hydrogen technology.Considering large scale wind power investment,the impacts of three types of electrolysis technologies and two types of hydrogen production modes on hydrogen costs and volume are studied.The economic advantages and emission reduction effects of green hydrogen production in China is discussed based on the real-world data of West Inner Mongolia region.(3)The coordinated optimization of supply and demand in distributed energy system is studied.The study is established based on the aforementioned demand simulation and energy system optimization methods.The thesis firstly analyzes the impacts of EV penetration and charging patterns on the management of existing distributed systems.With the proposed multi-agent operational optimization framework,the impacts of uncontrolled charging,off-peak charging and flexible charging and discharging on the energy demands,dispatching and costs of the system are quantified.After this,three types of demand resources,i.e.,shiftable loads,sheddable loads with thermal inertia and EV flexibility,are integrated into the bilevel CCHP system optimization framework for capacity planning and hourly dispatching.The impacts of different types of demand resources and the relationship between DR and system off-design operation are studied.The results prove the effectiveness of supply and demand coordinative optimization.(4)The complementary optimization of supply and demand in the regional interconnected centralized energy systems is studied.Firstly,based on the socioeconomic information and the future energy policies,the thesis analyzes the energy demand characteristics of building,transportation,agriculture,and industry sectors for each region.Considering the spatial and temporal distribution of regional demand and renewable resources,the FUC based system optimization model finds the optimal technology combination of onshore wind power,solar power,hydropower,thermal power,hydrogen production,various energy storage and high voltage transmission to explore the economical carbon neutral roadmap.Then,the thesis explores the possibility for cross-regional supply and demand complementarity that a significant source of green hydrogen could be produced by electrolysis fueled with China's offshore wind power.The study presents a cross-sea supply chain optimization framework for determining the ultimate costs of the green hydrogen,including expenses for production,storage,conversion,transport,and treatment at the destination.The hydrogen costs and export volume of coastal provinces are analyzed according to the wind resource data of 30 years.It concludes that China could play an important role in the world's carbon dioxide emission reduction.