Research On Fault Location Of Power Cable Based On Time-frequency Domain Joint Analysis Method

In 2019,State Grid put forward the strategic goal of building "three types and two networks",firmly develop the construction and operation of a strong smart grid,and deeply study the new technologies ubiquitous in the power Internet of Things.As a hub connecting energy production and consumption,the power grid is widely used in various fields of production and life.In the long-term operation process,it is inevitable to be attacked by including high temperature,mechanical tension,chemical corrosion,etc.Once the power cable failure accident will bring huge economic losses to the society.Cable fault location is an important technology for maintaining the normal operation of the power grid,and the accuracy and reliability of cable fault location are increasingly increasing.In view of the existing defects of Time Domain Reflectometry and Frequency Domain Reflectometry in existing cable fault locating technologies,consider using Time Frequency Domain Reflectometry(TFDR)Perform fault detection on power cables.TFDR uses Gaussian Envelope Linear Chirp(GELC)signal as the incident signal.The CELC signal can be designed according to the channel transmission characteristics of the cable,and the Wigner-Ville Distribution(WVD)is used to calculate the CELC signal.Time-frequency cross-correlation characteristics and time-frequency analysis to improve fault location accuracy.This paper focuses on the fault location of TFDR in power cables,and conducts research from the following two parts:The first part is about the fault location research of TFDR under the noise characteristics of power line channels.Considering the complexity of power line channels,impulse noise is the main factor affecting the quality of power line communications.This will inevitably lead to cross-term interference in WVD in TFDR.The problem is to compare Pseudo Wigner-Ville Distribution,Smooth Pseudo Wigner-Ville Distribution(SPWVD)and Choi-Williams distribution under different window functions Distribution to suppress cross-term interference performance,and proposed to eliminate cross-term interference and impulse noise based on SPWVD and time-frequency filtering respectively.According to the time-frequency distribution characteristics of CELC signal,Hough transform is used to identify and characterize the CELC signal under SPWVD Locate the fault.Simulation and time-frequency analysis prove the effectiveness of the method.The second part is to design and implement the TFDR power cable fault location method,considering the actual fault location process under the actual TFDR,the implementation design plan is divided into 4 modules,for which CELC signal generation module,DA module and WVD calculation Modules,using System Generator,Vivado and other rapid design tools,IP design of different modules,hardware acceleration on the Zynq-7000 development board.Verification of the feasibility of the entire program through actual tests.