Sequential Power Flow Calculation Of Integrated Electric And Heating Systems Based On Refined Heating Network Model

The essence of traditional integrated energy system power flow calculation is to calculate the operating status of the entire system based on some known variables in the system by using Newton method or forward-backward sweep method.With the deepening of the research on this issue and the continuous improvement of the power flow calculation model,considering the hydraulic model and the thermal model in the heat network in a more refined fashion and investigating the differences in the types of the heat network nodes will support a more accurate power flow calculation of the electric heating integrated energy system,and provide a basis for operation dispatch and planning configuration.However,the existing literature on the power flow calculation of integrated electric and heating systems fails to consider the dynamic characteristics of thermal energy transmission in the heat network and local resistance of pipe water flow in detail,or to clearly define the types of load nodes in the heat network.To address this issue,this paper proposes a sequential power flow calculation method for electric heating integrated energy system based on a refined heat network model.The specific research content is as follows:Firstly,the basic theories which this paper is founded on are introduced,including the theory of heat network graphs describing the topology of the heating network,the Newton-Raphson method for solving nonlinear equations,and the general form and solution method of partial differential equations.Secondly,considering the influence of various resistances on the pipe mass flow in the heat network pipeline,a hydraulic model is constructed.Then,to investigate the temperature changes of the supply and return water in the pipe,the interaction between the microelements in the heating network pipeline is analyzed while a thermal model and a pipeline temperature solution model considering the dynamic characteristics of the heating network are constructed.Thirdly,the typical architecture and equipment energy efficiency model for electric heating integrated energy system are constructed,and various energy supply modes in the system are analyzed.Then,the sequential problem and the electro-thermal coupling problem in the power flow calculation of the system are addressed,and the load node types of the heating network are redefined.Next,the hydro-thermal calculation method in the heating network is revised.Based on the sequential calculation method of the electric/thermal systems,a sequential power flow calculation method of the electric heating integrated energy system considering both the dynamic characteristics of the heat transfer and the refined resistance is proposed.Finally,the power flow distributions of the electric heating integrated energy system under different scenarios are compared by actual case studies,and the effect of the refined heat network model on the system scheduling is analyzed,which proves the effectiveness and practicality of the proposed model in the electric heating integrated energy system.The results show that: the hydraulic model that considers refined resistance into the power flow calculation of an electric heating integrated energy system can accurately compute the change of mass flow in the pipe and narrow the gap between the mass flow and the pressure drop in the pipeline;the thermal network model with dynamic characteristics can avoid ignoring the transmission delay in the traditional steady-state power flow analysis of heating network,and analyze the rules of temperature change of the pipeline and nodes more accurately;the refined thermal network model can also effectively lower the cost of the system in operation dispatch.