Research On Fault Location Method Of Active Distribution System Based On μPMU

Accurate and fast fault location technology is of great significance to ensure the safe and stable operation of distribution network.In recent years,the large number of accesses of distributed power supplies and electric vehicles put forward higher requirement for the safe and stable operation of distribution networks.Impedance method has advantages such as low cost,easy implementation,and strong anti-interference.It was widely used in practical engineering.However,the inaccurate distribution line parameters has a great influence on the location accuracy.At the same time,the actual distribution line asymmetry is more serious,which also affects the fault location accuracy to some extent.In addition,the traditional impedance methods use amplitude information of voltage and current sequence component,but amplitude accuracy is restricted by the transformer and oparation conditions,which is difficult to improve.With the development of the Micro Phasor Measurement Unit(μPMU)technology and its application in the distribution network,a large number of synchronized and accurate phasor information can be obtained.It provides technical condition for improving the accuracy of fault location algorithm.Therefore,the research on fault location technology of distribution network based onμPMU information has received extensive attention.In this paper,the active distribution network is taken as the research object.The research in this paper is mainly divided into three parts:the fault characteristics analysis of small current grounding system,the fault location algorithm based on μPMU phasor information,and the influence of μPMU error on the proposed algorithm.The specific research contents are as follows:1)Considering the influence of system neutral grounding ways,line parameters and istributed generators on fault location,the small current grounding system is modeled.The single-phase ground fault is taken as the main research object.This paper analyzed the distribution characteristics of voltage phasors along the fault line,and the influence of distributed power on fault characteristics.2)This paper proposed improved fault location method based on μPMU phasor information.Combined with the normal operation data and fault data of the μPMU,convert the problem to be solved into a convex optimization problem.The line parameter and the fault distance are used as unknowns,the objective functions are formed by two-terminal and three-terminal voltage phasor.On the basis of considering the amplitude information,the angle constraint is added.The internal point method is used to simultaneously solve real-time line parameters and fault distance.This method greatly improved the location accuracy compared to the traditional method.The result is not affected by the distributed generators,and is applicable to different fault types,different transition resistance sizes,different neutral grounding ways and different line types.3)This paper proposed a μPMU amplitude measurement error model.The Monte Carlo(MC)method is used to obtain the fault location error samples under the influence of PMU error.Based on Gaussian Mixture Model(GMM)and optimal fitting method.(Fit of Fit,GOF)analyzes the probability distribution characteristics of measurement error and fault location error.The Gaussian distribution of the above errors is obtained,and the algorithm has high accuracy and stability under the influence of error.The μPMU error feature model is established.The Monte Carlo method is used to obtain the fault location error samples under the influence of μPMU measurement error.The probability distribution characteristics of measurement error and fault location error are analyzed based on Gauss Mixture Model(GMM)and Fit of Fit(GOF).The Gaussian distribution of the above errors is obtained,and the algorithm has high accuracy and stability under the influence of error.