Study On Fault Monitoring Techniques Of High-Voltage Power Cables

With the development of modern industry and the improvement of urbanization level,power cables as the important tool to transmit electrical energy, get more and more attentionand application. The operation reliability of power cables directly affects the normal operationof power system. Thus the fault monitoring for high-voltage power cables is particularlyimportant. Faults of power cables are closely related to their insulation situations. Defects ofmain insulation inevitably bring the partial discharge phenomenon, while the change of thepartial discharge value indicates that the cable insulation may have defects endangering thesafe operation of the cables. Therefore, the accurate measurement of partial discharge valuesfor cables is the most intuitive and ideal way to judge the insulation quality of cables. Thepartial discharge monitoring and analysis is of great significance for the judgment of thepower cable fault.Taking high-voltage XLPE power cables as the studied objects, this paper presents thestatus and development trend of insulation diagnostic technology for power cables at homeand abroad. In terms of macroscopic and microcosmic respectively, the reason and type ofpower cable faults are analyzed in this paper. Associating with the operating practice ofGuangzhou Power Supply Bureau, this paper makes a count and analysis on the reason andposition of operating cables which are liable to failure. Also, it puts forward the correspondingpreventive measures. Besides, it illustrates by several fault monitoring methods in commonuse.On the basis of summarizing and analyzing the existing monitoring methods of partialdischarge for power cables, the paper emphatically illustrates fault online monitoring systemestablished by the transmission department of Guangzhou Power Supply Bureau transmission.By the application of online and offline monitoring for partial discharge and the fault locationmonitoring technology, the defects of operating cables can be reflected more intuitively andthe point of failure can be found in time after the failure occurred.The partial discharge signal of cables in the actual detection is inevitably mixed withmany other kinds of noise signals. This paper analyzes the types and sources of the commonnoise in the partial discharge measurements for cables. According to analysis and extractionof the signal feature, interference noises can be deleted effectively so as to improve theaccuracy of partial discharge monitoring.This paper discourses the location monitoring of failure point for cables. The propagationtime of fault transient traveling wave between the point of failure and both ends of the cable is adopted to online calculate the distance from the point of failure to either end of the cable, soas to achieve real-time and accurate positioning for the cable faults.