Research On On-line Monitoring Technology Of High Voltage Cable Insulation Based On Transient Traveling Wave

With the development of science and technology as well as the advancement of urbanization, it has become the inevitable trend to use cable lines instead of the original overhead lines during the development of city power grid and the application of cable lines in high voltage power is becoming more and more widely spread. The reliability of its operation is related to the safe and stable operation of power system directly. In order to ensure the reliability and the quality of power supply, the online monitoring of high voltage power cable insulation faults counts more. Therefore, this paper presents a method for on-line monitoring of insulation by using high voltage power cable of transient traveling wave, which can achieve the prediction as well as the positioning of the main insulation fault at the same time, and the alarm rings when any accident happens to the outer part of the cable lines. The paper includes the following parts:(1)The basic structure of high voltage power cable has been analyzed, and the ground connection method needed by the simulation model has been chosen through the analysis of metal sheath grounding mode. The main insulation fault as well as and the traveling wave process of the main insulation fault are analyzed together by using fault component diagram. The characteristics of fault transient of the outer sheath insulation can also be got here. Under the studies and analyses above, the simulation model of main insulation fault and the outer sheath insulation fault has been established, and respective analyses of the fault transient simulation have also been reached.(2)The algorithm and criterion have been put forward respectively to the faults of the main insulation and the outer sheath through the analysis of them. When the judgment of the main insulation is satisfied, the traveling wave fault location algorithm is used to work out the distance. At the same time, the project to improve the results of measurement, called 3a method is used to deal with the huge numbers. The way to identify the main insulation and the outer sheath is also given. So is the identification of the faults of the ground connection of the armored layer as well as the metal shielding layer.(3)In order to identify the algorithm and criterion mentioned above, PSCAD technology is used to simulate the two types of faults and fault data is got from it. MATLAB software programming algorithm is also used to identify the reliability and correction of them. At the same time, all the faults in the main insulation, the outer sheath, the ground connection of the armored layer and the metal shielding layer are identified.(4)The overall scheme of the system is presented in this paper and the software program of the system is also presented after the introduction of high speed data acquisition module and wireless communication module.