Steady-state Simulation Analysis And Energy Optimization Method Of The Regional Electricity And Heat System

Combined heat and power(CHP)units,electric boilers and other energy coupling components are widely used,which makes the coupling among electricity,heat and natural gas energy systems increasingly close.The derived integrated energy system(IES)aims to fully tap the potential of energy cooperation,improve energy utilization efficiency,and promote a new round of energy revolution.The regional electricity and heat system is a typical integrated energy system.This paper takes the regional electricity and heat system as the research object,focusing on the two objectives of steady-state analysis and simulation and energy optimization.The system modeling,combined power flow algorithm,simulation scheme and convex optimization are studied respectively.In this paper,the basic model of the electricity and heat system is established,and the balance nodes and variable types of the combined model are set up.For the regional heat network,based on the knowledge of graph theory,the correlation matrix and loop matrix are established;the hydraulic model and thermal model are modeled in detail,and the node flow balance equation,loop pressure balance equation and thermal model calculation matrix are defined;the electricity and heat power relationship of CHP,electric boiler and other coupling components is analyzed.Then,according to the position of the coupling components in the system,this paper classifies the electricity and heat system,and analyzes its power flow algorithm by selecting two typical operation modes,i.e.grid connected and off grid.In the existing combined power flow calculation methods,the integrated method has the problems of low efficiency and ill conditioned Jacobian matrix,while the decomposed method lacks the analysis of convergence property and the solution to iterative divergence.In order to solve these problems,a new combined power flow algorithm based on the principle of power conservation and the principle of fixed point iteration is proposed in this paper.The fast convergence and accuracy of the new algorithm are verified by a simulation example.It is proved that the new algorithm can solve the combined power flow without the convergence of the decomposed method,and can analyze and plan the feasible region of the coupling components.Next,in order to solve the problem of lack of steady-state simulation scheme for IES,this paper proposes a time series collaborative simulation scheme based on message bus.The scheme mainly includes message management and synchronization management mechanism.In the aspect of message management,subnetwork constraints are modularized to fit the subscription and publishing mechanism in message bus,and then the subscription relationship of coupling variables in the system is analyzed;in the aspect of synchronous management,event triggering mechanism is established according to the characteristics of time series power flow,including disturbance variable triggering and controller triggering,and time synchronization rules are proposed.The simulation results show that the method has good scalability and reusability,and can effectively simulate the time series power flow of IES.Finally,this paper studies the convex optimization method of the regional electricity and heat system.According to the criterion of the disciplined convex programming(DCP),the nonconvex model in the equality constraint of the optimization model is convex treated.Among them,the method of partial approximation and second-order cone relaxation is adopted for the electricity equation,which improves the calculation accuracy of the grid loss while ensuring the convex optimization;for the regional heat network,the relatively stable characteristics of the heat loss are proved by derivation and simulation calculation,and then the equivalent model of the heat network is proposed by equation transformation,which realizes the decoupling of the thermal model and the hydraulic model;for the heat network.In order to satisfy the DCP rule,two methods are proposed,which are linearization approximation and convex relaxation.The simulation results show that the convex optimization method has good accuracy.