Cable fault location method

Author: Noyafa–Cable Tester Suppliers

Power cables are susceptible to failures due to a variety of factors during operation, threatening the safety and reliability of the system. Therefore, the rapid and accurate detection of cable failures and their locations can help improve power supply reliability, reduce fault repair costs and power outages. The loss has important theoretical significance and practical value. 1. Introduction The electric power industry is the pillar industry of the national economy, and it is also the guarantee for the stable development of other industries. Therefore, ensuring the safety and reliability of the power system operation is the key to the stable and rapid development of the national economy.

Transmission lines are responsible for the important task of transmitting electrical energy and are the economic lifeblood of the power system. Their faults directly threaten the safe operation of the power system. Various faults frequently occur on power transmission lines. At the fault point, some fault phenomena are more obvious and easy to identify, while others are less obvious. For example, when a single-phase ground fault occurs in an ungrounded neutral system, the damage caused at the fault point is small due to the small ground current. After the protection removes the fault, it is sometimes difficult to find the fault point, but this fault point is relatively weak compared to the entire line because the insulation has changed, so it is likely to be the place where the next fault occurs. Therefore, it is still necessary to quickly find its location.

Cable fault location is also known as fault location. For transmission lines, it means to quickly and accurately determine the location of the fault point according to different fault characteristics after the line fails. How to quickly and accurately determine the line fault point is the basic task of cable fault location, and it is an important research topic in the field of power system. For a long time, due to the low accuracy of cable fault location, it not only affects the power supply recovery time of the faulty line, but also brings a heavy burden to the line operation and maintenance personnel to check the line.

Therefore, it is of great practical significance to make full use of the new development of science and technology to study and discuss the cable fault location algorithm of transmission lines and improve the line location accuracy, which is conducive to improving the social and economic benefits of the power production sector. 2. Research and development of distance measurement methods at home and abroad Because cables have a very significant impact on the safe and economic operation of the system, starting from the application of cables, people have invested a lot of work in researching cable fault location methods both at home and abroad. With the expansion of cable application fields, the change of the nature of cable faults, and the continuous development of cable fault location methods, it can be said that this is a classic and new technology. From the perspective of positioning technology: the development of cable fault positioning methods can be divided into three stages: (1) Direct testing stage. In the 1960s and before, engineers and technicians generally used the bridge method to directly measure the distance from the fault point to the test point. .

(2) In the test stage of analog storage technology, in the 1970s, the maturity of high-voltage analog storage oscilloscope technology led to the development of cable fault location technology. The traveling wave theory was applied in the test, and the test of high resistance faults was faster, which made the cable fault detection. The means is a huge step forward. (3) In the testing stage of digital technology, in the late 1980s, based on the digital transient waveform measuring instrument invented by Biomation, the cable fault location method made a qualitative leap. After the data is processed by digital filtering, the voltage and current traveling waves propagating in the cable can be analyzed in detail, so that a comprehensive understanding of the nature of the cable fault can be obtained, and the location measurement of the fault point of the cable can achieve a very high accuracy, which is also the current cable fault. The main method used by mainstream products in the field of fault detection. In recent years, many novel cable fault location methods have been proposed, such as optimization methods, Kalman filter technology, pattern recognition technology, probability and statistical decision-making, fuzzy theory and fiber-optic ranging methods, which are mostly in the research stage.

The fault of the cable is very complex, and there is no one-size-fits-all instrument that can detect all the faults. According to its main functions, it can be divided into the following categories: (1) Simple portable testing equipment. This type of equipment has a simple structure and a single function, and is an early product.

(2) Testing equipment with certain additional functions. This type of product can simply process the test data and have certain additional functions. (3) A powerful detection system.

Most of this type of equipment is composed of foreground detection, data transmission, background control processing and other parts. It has the functions of collecting, transmitting and processing status data. Through basic operations such as data transmission, timing detection, automatic detection, and real-time operation, it can complete detection functions such as the determination of the cable air pressure value, estimate the cable leakage point, etc., and warn the maintenance personnel, and can be stored in the established system database. The technical data and maintenance files of the line greatly facilitate the maintenance and reconstruction of the line by maintenance personnel and engineering technicians.

This system has changed the traditional inflatable maintenance mode and effectively improved the maintenance quality and management level of line equipment. It can be seen that with the continuous improvement of technology, the accuracy and practicability of ranging are also continuously improved. However, the traveling wave ranging method still has the problems of non-directionality, dead zone in the outlet short circuit, and high hardware cost.

Due to the complexity of faults, the current equipment cannot be used for all types of faults, and there is a contradiction between measurement accuracy and cost.