Study Of Fault Location Method For Distribution Network Overhead-cable Hybrid Transmission Line

Due to the safely and reliably power supply,beautifying the city appearance and so on,cable line has been more and more widely used in our country.So,there are more and more overhead-cable hybrid lines on the basis of the original structure of a single overhead.The neutral point of ineffective grounding method is widely used in our distribution network,whose single-phase grounding fault rate is highest.When single-phase fault occur,the fault phase voltage will rise.It is easy to cause the insulation breakdown.Therefore,single-phase fault seriously threaten to the power distribution network.Because of complicated power distribution network structure and the line type,it is difficult to implement the fault location.First of all,this paper analyzes the structure characteristics of overhead lines and cable line,as well as the transmission characteristics of fault traveling wave.Secondly,this paper introduces the principle of empirical mode decomposition(EMD)and its application in power system.Due to the affection of the EMD in modal aliasing and boundary,the EMD traveling wave singularity detection methods are optimized.Again,based on the principle the distributed parameter method and the single-ended fault location,this paper propose a composite fault line Bob recognition method.It solves the problem of inconformity in the overhead lines and cable wave impedance.In addition,this article combines parameter range method with the single ended traveling wave ranging method,and puts forward a kind of suitable method for distribution network fault location.Finally,using PSCAD simulation and MATLAB programming,the proposed method has carried on the simulation.The results show that the proposed method in terms of reliability and accuracy are improved greatly;In addition,the proposed method is applied to the fault location device WFL – 2010.It implements the fault testing signal de-noising,analysis and processing,fault distance calculation and test data such as intact ranging function.It further proves the practicability and feasibility of the proposed method.