Low-carbon Economic Operation And Optimal Placement Of Electricity-gas Integrated Energy System

An integrated energy system(IES),formed by integrating and optimizing multiple energy systems,provides a new solution to energy and environmental problems.An IES can make full use of the complementary characteristics and synergies among different energy systems,thereby improve the comprehensive energy efficiency and the renewable energy accommodation capability of the whole system,which is of great significance for promoting the energy structure transformation.As the coupling link among multiple energy systems,the energy hub(EH)can realize the conversion,distribution and flexible storage of various energy carriers.The types,capacities and operation modes of components in an EH play an important role in the secure and economic operation of the IES concerned.Given this background,some preliminary studies have been carried out on related topics and are summarized as follows:The typical architecture and general model of the IES are proposed.Firstly,a typical physical architecture of the IES is constructed,which is composed of multiple EHs connected by multiple energy networks.Based on this architecture,a universal model of the IES consisting of the EH model,electric network model and natural gas network model is proposed.The establishment of the model lays a theoretical foundation for the following research on the low-carbon economic operation and optimal placement of the IES.An optimal operation model of an IES considering carbon trading and flexible loads(FLs)is proposed.First,the carbon trading based on the IES is presented,taking into account the carbon emissions of the entire energy supply chain.Next,FLs are divided into three categories,i.e.curtailable,transferable and shiftable ones,which are introduced into the low-carbon economic operation model of an IES.On this basis,the energy coupling constraints,electric power system operation constraints,together with natural gas system operation constraints are integrated into a low-carbon economic operation model considering FL,with an objective of minimizing the operation costs including the carbon trading cost,flexible loads dispatching cost and system energy cost.Finally,a 9-hub IES testing system is employed to as an example,the model and the method adopted in this thesis are exemplified,and the effect of carbon trading price on IES carbon emissions and operating costs,as well as the impacts of FLs on wind power accommodation and emissions reduction are analysed.An optimal placement model of EHs considering the N-1 security criterion in the associate power system is proposed.First,with the minimization of the annual comprehensive cost as the optimization objective,an joint optimal placement model of EHs is established,with the energy coupling constraints,electric power system operation constraints,natural gas system operation constraints,together with N-1 security constraints of the electric power system all taken into account.Next,the optimal placement model is transformed into a mixed-integer second order cone programming model by second order cone relaxation technique and then solved by the YALMIP/GUROBI commercial solver.Finally,a sample IES is employed to demonstrate the presented optimization model and solution method.The results of case studies show that considering N-1 security criterion in the IES optimal placement problem is beneficial to realize the coordinated optimization of economy and security of the IES.