Cable water tree branch fault positioning method based on impedance spectrum technology

Abstract

The invention relates to the technical field of fault positioning, and discloses a cable water branch fault positioning method based on an impedance spectroscopy technology. The method comprises the steps of deriving a cable distribution parameter frequency change effect broadband impedance calculation model based on a transmission line theory; calculating cable line impedance by using the broadband impedance calculation model, and forming a cable broadband impedance spectrum; utilizing an algorithm to optimize a difference value function of an impedance spectrum calculation value and a measurement value to obtain defect section characteristic parameters; utilizing a linear resonance analysis method to analyze the defect section characteristic parameters so as to determine characteristic information of a defect section cable; analyzing the characteristic information of the defect section cable to diagnose the running state of the cable, detecting the change condition of the running state of the cable, and determining the water branch fault position of the cable. Compared with the prior art, the impedance calculation model is deduced through the transmission line theory, local defect characteristic parameters are extracted from impedance spectrum data, and accurate positioning and state evaluation of cable aging, damage and other defects are achieved.

Description

technical field [0001] The invention relates to the technical field of fault location, in particular to a cable water branch fault location method based on impedance spectrum technology. Background technique [0002] With the application of power cables in power systems more and more widely, the insulation state of power cables directly affects the safe and reliable operation of power systems. The power cable is the link and bridge of the power supply network, and its status monitoring and fault diagnosis are of great significance to ensure the reliability of power supply. However, because the power system is huge, the execution cycle of the cable is relatively long, and the insulation aging is slow, so the monitoring and diagnosis of the cable have not attracted enough attention. In recent years, with the continuous increase of the capacity of the fleet, cables play an extremely important role in the transmission of electric energy and communication signals in large electr...

AI Technical Summary

Problems solved by technology

The design life of the cable is generally 20 to 30 years, and the cable in actual operation often induces permanent failure due to local latent defects such as local aging or damage of the insulation. Once a cable failure occurs, it will cause the shutdown or even loss of control of the large electrical system. Cause serious economic loss and social impact

[0003] After the cable is put into operation, the insulation will be affected by factors such as electricity, heat, machinery, and moisture, and will age, which will affect the operational reliability and service life of the cable.

More than 40 years of operation and research have shown that water treeing is the main factor leading to shortened insulation life of cross-linked polyethylene (XLPE) cables

The detection of local defects of power cables and water branches is a big problem. Oscillatory wave testing technology can only detect electric branches. Although the ultra-low frequency dielectric loss test can detect the existence of water branches of cables, it cannot locate water branches. The interception method for positioning is not only costly but also time-consuming, and it is difficult to find hidden dangers of processing equipment defects in time in the application of engineering technology

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