Monitoring leakage currents of suspension insulators of high voltage overhead power lines

The relevance of studying partial discharge currents (PDC) arising on the surface of suspension insulators of high-voltage overhead power lines (HVPL) is substantiated. Increasing PDC leads to increasing active energy losses and unauthorized shutdowns of high-voltage power lines due to the electric arc overlap of the suspension insulator. A laboratory bench for PDC experimental studying has been developed and manufactured. As a result of experimental studies we have determined static and dynamic characteristics of partial discharge currents; we have developed the algorithm for processing experimentally obtained results using Microsoft Excel spreadsheet editor. Recommendations have been developed for developing the hardware of the PDC sensor that allows increasing sensitivity, expanding the range of the controlled parameter and improving its dynamic characteristics in order to increase the accuracy and to expand the range of operation of the PDC sensor and to reduce the time it takes to establish its output signal. Equipping 220-500 kV power lines with PDC sensors of suspension insulators with telemetry will allow reducing the number of unauthorized emergency shutdowns of high-voltage power lines; realizing continuous current monitoring of the state of suspension insulators and receiving in real time the information of the integral value of PDC

Flashover Performance and Process of Suspension Insulator Strings Artificially Covered with Snow

Snow accumulates on the surface of insulator string, causing a decrease in its electrical performance, seriously threatening the reliable operation of the power grid. Most previous studies have focused on iced insulators; however, there is a lack of research on snow-covered insulators. In this paper, to reveal the influencing mechanism that snow has on the electrical characteristics of insulator string, based on an artificial snowing test in a chamber, the effects of equivalent salt deposit density, applied voltage type, and snow thickness on the flashover performance of snow-covered insulators are analyzed, and the flashover process is investigated. The results show that the relationship between the arc flashover gradient and the equivalent salt deposit density is a power function with a negative exponent, which is similar to that of polluted and ice-covered insulator strings. For the insulator strings with the same snow accretion, the direct current (DC) arc flashover gradient is lower than the alternating current (AC) arc flashover gradient. The relationship between arc flashover gradient and snow thickness is also a power function. The formation of a dry band during the flashover of snow-covered insulator string is similar to the flashover of the polluted insulator, and the arc propagation along the surface of the snow-covered insulator is similar to the flashover of the iced insulator.