The Evolution of Trapping Parameters on Three-Layer Oil-Paper of Partial Discharge Degradation for On-Board Traction Transformers

Abstract

Trap plays an important role in the charge transportation of three-layer oil-paper and the investigation of trap parameters at different degradation degree is of great significance for further research of the partial discharge (PD) mechanism. This paper considers the turn-to-turn structure of on-board traction transformer. A defect model of three-layer oil-paper insulation was designed for PD test. The PD degradation samples are selected from the inception of PD to the breakdown of PD to study the characteristics of surface potential decay on degradation samples by using isothermal surface potential decay method. Given that, the trap distribution at different degradation stages was calculated and its influence on PD characteristics was investigated. The result shows that AC fluctuation voltages caused by inter-harmonic has a great influence on PD distribution, surface charge distribution and trap distribution. With the increase of degradation, the decay rate of surface potential increases and the decay rate of AC fluctuation voltages is larger than that pure AC. And also, the number of shallow trap with AC fluctuation voltages is larger than that with pure AC. The rate of free charge increases with the number of shallow trap increasing. More free electrons involves in the process of PD, accelerating the aging rate of three-layer oil paper samples. Therefore, it can be concluded that surface charge and trap distribution are helpful to clarify PD mechanism.

Intelligent Online Partial Discharge Detection and Sensor

“…Li et al proposed the sono-optical measurement method, in which the ultrasonic wave in the process of local discharge squeezed the optical fiber and forced the chemical characteristics of chemical fiber to change. By detecting the change signal of the output optical fiber, ultrasonic wave could be measured and qualitative discharge could be indirect [6]. Aydoan et al introduced the extraction method of feature vectors for switch cabinet partial discharge pattern recognition.…”

Charge migration of multilayer oil paper on the process of partial discharge under AC voltage

“…It accelerates the formation of shallow traps in the second layer of the samples. Free charges seized by shallow traps may free quickly from them [28]. As a consequence, the charges trapped in shallow traps are easy to participate in the development of PD.…”

Surface Degradation of Oil-Immersed Nomex Paper Caused by Partial Discharge of High-Frequency Voltage

“…The previous investigations of PD damage characteristics in oil-impregnated Nomex paper under AC [13][14][15] indicated that the creepage tree phenomenon caused by dv/dt is observed. However, it can be found that the PD damage mechanism under HF stress is different.…”

“…Thirumurugan et al 12 studied the effect of different solid and liquid insulation materials on the surface PD characteristics, and discussed the topography and composition of samples during PD. Li et al [13][14][15] expounded the PD characteristics of oil paper and trap parameters of PD degradation, and concluded that surface charge and trap distribution are helpful in clarifying the PD mechanism. However, the above-mentioned literature mainly studied PD damage characteristics and the mechanism of oil-paper insulation under AC voltage.…”