Establishment Of Reliability Model Of Intelligent Distribution System

Intelligent distribution network is the development trend of distribution system.It is a complex distribution system based on advanced automation technology of distribution network and integrated with advanced control and measurement technology.Low cost,clean and environmentally friendly DG is the typical power generation equipment in smart distribution system.The existence of DG makes smart distribution system components more diverse.Considering the intermittence and fluctuation of DG,it brings new challenges to the reliability of power supply when DG is connected to smart distribution network.The reliability evaluation model and method of distribution system will be changed.The research on the reliability of DG has always been the focus and hot issue of academic research.The purpose of this paper is to evaluate the reliability of DG connected to intelligent distribution system represented by wind turbine and photovoltaic.Firstly,this paper introduces the reliability features of intelligent distribution network and the influence of DG access on intelligent distribution network,then establishes a reliability evaluation index system,summarizes the advantages and disadvantages of several commonly used analytical methods and determines their limitations,and analyzes the reasons why they are not suitable for reliability evaluation of DG connected intelligent distribution network.This paper discusses the simulation process and characteristics of Monte Carlo simulation method,and introduces the sequential Monte Carlo simulation algorithm for reliability evaluation based on sequential state sampling,which lays a foundation for the establishment of reliability model and evaluation algorithm of intelligent distribution network in the following chapters.Secondly,the state model of components,the output model and the reliability model of DG are established.The system is divided into several automatic isolation zones and the minimum isolation zones with the switchgear as the boundary,and the minimum isolation zone as the basic analysis unit of the system is determined.According to the power supply scope of DG,a heuristic reduction strategy is developed to ensure the load balance of the island operation mode.Taking the equivalent feeder area as the basic analysis and sampling unit of reliability evaluation,a regional Quasi-sequential Monte Carlo simulation method is proposed to solve the reliability model of DG-connected intelligent distribution network.Finally,according to the reliability evaluation model of DG access intelligent distribution network,the reliability of practical engineering cases is calculated and analyzed.Firstly,a traditional distribution network example is given.The reliability of the modifiedIEEE RBTS BUS6 is evaluated by using the sequential Monte Carlo simulation algorithm based on equivalent feeder area sampling.The accuracy of the Monte Carlo algorithm is verified by comparing the evaluation results with the analytical results,and the convergence of the Monte Carlo simulation algorithm is tested.Secondly,the modified IEEE RBTS Bus 6main feeder F4 and its branch feeder connected with DG are taken as examples to evaluate the reliability of intelligent distribution network under different DG access schemes.The results show that the islanding operation of DG has a great impact on the reliability of distribution network,and different types of DG can affect the reliability of intelligent distribution network.The results of assessment of sexual impact are also different.Aiming at the intermittent and fluctuating output characteristics of DG,the engineering application measures to improve the reliability of DG are studied from the point of view of configuring energy storage devices.