Research On Fault Reconfiguration Technology Of Distribution Network With High Permeability Distributed Generation

As an important hub for power supply and distribution,the distribution network directly affects the quality of power supply and user experience.When the distribution network fails,the system needs to quickly and accurately find the fault location,and quickly restore the power supply to the non-faulty area with less loss.With the continuous improvement of the smart grid and the massive access of distributed generation(DG)to the distribution network,the load changes have increased and the power flow direction has become more complex.Therefore,it is of great significance to study the fault reconstruction method of distribution network with high-penetration DG for the power supply of distribution network.This paper introduces the current development status of fault reconfiguration of distribution network with DG,analyzes the principle of DG grid connection and its impact on traditional fault location methods.The results show that the traditional method based on Feeder Terminal Unit(FTU)The fault location criterion is no longer applicable to the distribution network with high permeability DG.In order to solve this problem,this paper takes the small current grounding system as an example,firstly analyzes the zero-sequence current characteristics of the system when a single-phase grounding fault occurs,and studies the influence of DG access on the zero-sequence current.The sequence current group amplitude comparison method is used as a fault detection method,and a FTU state coding method is proposed for the ground fault of the DG distribution network with high penetration rate.Secondly,when a short-circuit fault occurs in the system,the directional index is introduced to set the fault criterion and FTU coding method suitable for the short-circuit fault of the distribution network with DG.Aiming at the shortcomings of existing intelligent algorithms for fault location,an improved Particle Swarm Optimization(PSO)algorithm is introduced.On the basis of the traditional particle swarm algorithm,a small-world network is added to enhance the global search ability of the algorithm,and at the same time,the idea of neighborhood search for suboptimal solutions is introduced to avoid premature stagnation of the algorithm.Aiming at the problem that the global search and local search capabilities of the algorithm restrict each other,a judgment relationship between the global search and the local search is constructed to further improve the convergence and accuracy of the algorithm.Aiming at the application of the improved particle swarm algorithm in the fault location of the distribution network with high permeability DG,this paper designs a new switch state code through the proposed FTU coding method,and improves the switching function to make it suitable for the distribution network with DG.At the same time,the fitness function is optimized,so that the algorithm has better fault tolerance and accuracy for the fault location of the distribution network with high permeability DG.After accurately locating the fault and isolating the fault,this paper firstly calculates the power flow of the distribution network with high penetration rate DG,formulates the islanding plan,and then constructs the failure recovery model with the smallest active power loss and the least number of switching actions.The objective function is solved by the improved PSO algorithm,and the optimal switch combination scheme is obtained.Taking IEEE33 node distribution system as an example,the simulation analysis of fault location and power supply restoration in non fault area is carried out in the simulation software MATLAB,which verifies that the improved PSO algorithm proposed in this paper has high reliability and applicability for the fault reconstruction of distribution network with high permeability DG.