Research On The Optimization And Risk Of Electricity-Gas-Heating Multi-energy In Integrated Energy System

Integrated energy systems consisted of electricity,natural gas,heat,wind power,solar power and other energy in various forms are increasingly favored by all countries in the world,along with the increasing diversification of people's demand for energy,the large-scale development and utilization of renewable energy,and the progress of distributed energy system technology.Duo to the proposal and development of the integrated energy system,the efficiency of the comprehensive utilization of energy has been improved,the cascade utilization and complementary advantages of various energies has been promoted,and the imbalance problem of energy supply and demand has been solved.Although the development of power-to-gas technology,distributed energy generation technology and ultra-high voltage transmission technology have laid a foundation for the development of the integrated energy system at all levels from park,city to region,the techno-economic analysis,the identification and measurement of risk drivers of the integrated energy system are still remained to be studied.Therefore,this paper takes the urban integrated energy system as the research object,studies the optimization of the conversion of heterogeneous energy sources,i.e.electricity,gas and heat in the system,the comparative analysis of economic and environmental benefits with the traditional energy supply mode,and the risk analysis and measurement of the integrated energy system.The main contents of this paper are as follows.(1)On the basis of the research background,section 1 expounds the purpose and significance of this study,analyzes the research status at home and abroad,then reviews the literature on the main research content of this paper from different respects,and finally elaborates the technical route,research difficulties,key issues and innovations of the paper.After that,the correlation analysis,stability analysis and quantile regression analysis are carried out in section 2,based on the energy consumption,price trend and market situation of electric power,natural gas and thermal power included in the integrated energy system.These studies lay the foundation for the following integrated energy system optimization and risk analysis.(2)Studying the energy conversion optimization of the electricity-gas-heat integrated energy system.The integrated energy system combines power grid,natural gas pipeline,district heating network,and renewable energy generation to enhance the accommodation of renewable energy and smooth the load demand profile.However,the system faces great uncertainty derived from the fluctuating renewable generation and demand load,etc.Therefore,this paper considers the wind power accommodation on the supply side and the load fluctuation on the demand side,combines the constrains coming from power grid,natural gas pipeline and heating network,and constructs a multi-objective optimization model for integrated energy system based on minimizing the fuel cost,the wind power curtailment and the variance of peak-valley load on end-user side as the objection functions.(3)Studying the optimization of natural gas consumption structure of the electricity-gas-heat integrated energy system.In the case of shortage of natural gas supply capacity,this paper mainly focuses on the overall optimization of the integrated energy system consumption structure under the circumstances of gas-electricity conversion and gas-heat conversion.Three objective functions of natural gas cost,wind power consumption on supply side and uncertainty of natural gas supply are explicitly considered.under the circumstance of uncertainty of natural gas supply and capacity restriction of gas turbine peak shaving.Combined with utility theory,the social utility and user utility that resulting from natural gas consumption are calculated,and eventually a natural gas consumption structure multi-objective optimal allocation model considering supply uncertainty and peaking capacity constraint is built.(4)Analyzing the economic and environmental benefits of the electricity-gas-heat integrated energy system considered geothermal energy.In order to effectively and rationally allocate resources,promote the accommodation of renewable energy,and boost the clean heating in cold areas,this paper mainly focuses on the heat energy,optimizes and designs the integrated heating system that incorporates geothermal energy into the framework of the electricity-gas-heat integrated energy system.Afterwards,a scenario approach is deployed.Based on the gas peak-shaving ratio and the ratio of geothermal heating loads to the basic heat loads,twelve scenarios are defined and simulated,then the environmental and economic benefits of the integrated heating system and coal-fired boiler central heating under different scenarios are analyzed.Further,the sensitivity analysis of the heat source to the uncertainties is carried out.The uncertainties refer to the energy price factors,the peak-shaving ratio of gas-fired boiler and the ratio of basic heat load of ground source heat pump.(5)Constructing the risk framework of electricity-gas-heat integrated energy system.First,the risk sources of the integrated energy system,including capital flow,energy flow and information flow,are identified,and the capital-energy-information risk framework of the integrated energy system is constructed according to the physical entity composition,business entity operation and virtual value analysis.Second,in the framework of risk,the time sequence analysis of market level risk,the correlation analysis of physical level risk and the stability analysis of information level risk are carried out.Moreover,the reliability of power system,natural gas system and thermal system are studied respectively,the risk of integrated energy system failure is assessed,and the causes of power system failure are analyzed using the failure tree analysis method and grey correlation analysis method.(6)Measuring the market risk and energy coupling risk of the electricity-gas-heat integrated energy system.The risk drivers that affect the energy market and the energy production,transmission and conversion in the integrated energy system are complex.For example,the fluctuation of energy price and the uncertainty of supply and demand often bring risks to the energy conversion and energy coupling in the integrated energy system.In this paper,the energy market yield and the output of various types of units are used as cut-in points to measure the market risk and energy coupling risk of the integrated energy system.In the beginning,the time series of risk factors change and the output profile of each energy unit in the integrated energy system are collected.Then the marginal distribution of risk factors and unit output in the integrated energy system are determined using the non-parametric kernel estimation method.Next,the nonlinear dependent structures among risk factors and unit output are described through the optimal copula function that is selected by the means of the maximum likelihood estimation method and minimum Euclidean distance.Finally,the market risk and energy coupling risk of the integrated energy system are measured by applying the copula-CVaR model.