Influence of tip corona of free particle on PD patterns in GIS

This paper investigates the influence of tip corona of free linear particle on the partial discharge pattern. The reduced scale apparatus of 126 kV GIS is set up in the laboratory. Linear particles with the same radii, same length and different tip radii are respectively placed in the experimental tank. The discharge signal, ultrasonic signal and movement track of linear particles were recorded and observed. The results indicate that: (1) Movement behavior of linear particles without corona on the tip mainly pass through four kinds of states with the increase of the applied voltage: static standing, jumping with a small height, jumping with a big height and jumping to high voltage electrode. As for the linear particles with corona on the tip, it only jumps with a small height rather than jumps to high voltage electrode. (2) In the low voltage, the V-φ ultrasonic signal scatter plot and q-φ discharge pulse signal scatter plot of both kinds of the linear particles with and without corona on the tip have strong phase correlation. Among them, the phase correlation of the discharge signals and the ultrasonic signals of the particles without corona on the tip decreases with the increase of the applied voltage, while the phase correlation of that of the particles with corona on the tip always keeps strong with the increase of the applied voltage. By analyzing the effect of tip corona on the particle motion and discharge characteristics, the discharge characteristic spectrum of linear particle with tip corona is obtained, which can provide important reference for pattern recognition of particle.