Ma Guoming

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.

Study on measurement of VFTO based on electric field sensor

In power system, pulse voltage is measured by both the circuit and the electric field. The special measure of VFTO is determined by non-alterable equipments of GIS. In this paper, external transient voltage is measured by electric spherical probe which means it is not necessary to access any equipment to the system. According to actual space between three phase external lead wire in GIS, we built the model, demarcated the system and imposed pulse voltage, the result of which indicated the feasibility. In addition, sphere probe improved measurable frequency range in the measuring system. From the experiment, we get transformation properties of electric spherical probe, and put forward two methods of rebuilding transient voltage of line based on transient voltage measured by spherical probe.

Measurement study of very fast transient overvoltage in GIS

In power system, pulse voltage is measured by both the circuit and the electric field. The special measure of VFTO is determined by non-alterable equipments of GIS. In this paper, external transient voltage is measured by electric spherical probe which means it is not necessary to access any equipments to the system. According to actual space between three phase external lead wire in GIS, we built the model, demarcated the system and imposed pulse voltage, the result of which indicated the feasibility. In addition, sphere probe improved measurable frequency range in the measuring system. From the experiment, we get transformation properties of electric spherical probe, and put forward two methods of rebuilding transient voltage of line based on transient voltage measured by spherical probe.