Hardware Design Of Portable Cable Fault Locator

Modern society cannot do without the supply of electricity,and power cables are the main component of power transportation.The rapid development of power systems has led to a significant increase in the number and length of lines in operation,and the frequency of cable accidents has increased.Power cable security will directly affect the supply of energy and the stable operation of society,and the timely detection of cable faults is of great significance.Most of the commonly used cable fault detectors cannot precisely locate the cable fault points,while the foreign LIRA fault detectors are expensive and costly to use.To address this problem,this paper studies the cable local fault detection method based on the input impedance spectrum and proposes a fault location method based on the phase shift constant;a portable cable fault locator is designed,and the application of the fault location method is realized by using the faulty cable for actual measurement and verification.The main contents of this paper are as follows:(1)Build a cable model based on transmission line theory.The distribution parameters of the cable are analyzed;the correlation between the input impedance spectrum and the propagation coefficient and characteristic impedance is explored;the parameter model of the faulty cable is established;the cable distribution parameters are investigated to be affected by local breakage;and it is determined that local breakage can affect the input impedance spectrum of the cable.(2)The cable fault location method is improved.Using the property that the local fault of the cable can affect the input impedance spectrum,the conversion of the input impedance spectrum from the frequency to the spatial domain related to the cable length is realized by using the integral transform.A fault location algorithm based on the phase shift constant is proposed,which has better high frequency characteristics and higher location accuracy,and is verified by simulation for comparison.(3)An impedance acquisition scheme is designed,mainly using an amplifier as the main body of the auto-balancing bridge,and using AD8302 for gain and phase difference measurements.And a design of phase polarity determination based on phase shift is proposed to improve the system accuracy.The hardware system scheme is designed,mainly including signal source design and filter design,power supply device design,USB transmission design,and ZYNQ main control system design.(4)A test platform was built to collect data from the actual cable and to locate faults on the test results.The feasibility of this system design was verified.The functional modules of the system were verified and debugged,and the measurement errors were improved.