Evolution of pd patterns in polyethylene insulation cavities under AC voltage

Abstract

In the framework of developing defect-based life models, in which breakdown is explicitly associated with partial discharge (PD)-induced damage growth from a defect, ageing tests and PD measurements were carried out in the laboratory on polyethylene (PE) layered specimens containing artificial cavities. PD activity was monitored continuously during aging. A quasi-deterministic series of stages can be observed in the behavior of the main PD parameters (i.e. discharge repetition rate and amplitude). The evolution of the parameters reflects the physicalchemical changes taking place at the dielectric/cavity interface during the aging process. PD activity shows similar time behavior under constant cavity gas volume and constant cavity gas pressure conditions, suggesting that the variation of PD parameters may not be attributed to the variation of the gas pressure. It is speculated that the change of PD activity is related to the composition of the cavity gas, as well as to the properties of dielectric/cavity interface.

Numerical Simulation of Temperature and Pressure Changes due to Partial Discharges in Spherical Cavities Within Solid Dielectrics at Different Ageing Conditions

“…In order to reproduce experimental measurements at ageing phases C to E, the initial pressure has to be decreased for considering the changes in the gas consumption and gaseous by-products generation rates [30]. After about 30 min, in ageing phase B, the pressure in the cavity starts to decrease continuously [18] with a decreasing rate that is voltage and temperature dependent [29].…”

“…In addition, affectations to cavity surface due to temperature increments can be discarded.Energies 2019, 12, 4771 2 of 11 Analytical models, in spite of their simplicity, are electrostatic field-based approaches and when homogeneous and symmetrical conditions are considered, such as cylinders or spheroids, the solutions obtained through analytical and FEA models are similar [15], and have the advantage that less computational time is required when simulations for a great number of periods of the AC-voltage signal are required such as in ageing analysis.PD are inherently multi-physical phenomena where electrical, thermal and mechanical physics are involved in each PD event [16]. Processes such as electron generation rate and surface charge decay through surface conduction are temperature and pressure dependent [17][18][19]. On the other hand, temperature affects the ageing process in solid dielectrics mainly due to the acceleration of chemical ageing dynamics [1].In this paper, the analytical and thermal models are presented in Section 2.…”

“…PD are inherently multi-physical phenomena where electrical, thermal and mechanical physics are involved in each PD event [16]. Processes such as electron generation rate and surface charge decay through surface conduction are temperature and pressure dependent [17][18][19]. On the other hand, temperature affects the ageing process in solid dielectrics mainly due to the acceleration of chemical ageing dynamics [1].…”

Evaluation of Low Cost Piezoelectric Sensors for the Identification of Partial Discharges Evolution

“…Thus, a PD can be detected by measuring and analyzing its signals and changes. The detection and the evolution identification of PD is greatly relevant, since the occurrence of these failures can be a primordial indicator of problems in the insulation system, and the progression of this phenomenon can cause a total failure of the transformers [12].…”

Online partial discharge signal conditioning for φ – q – n representation under noisy condition in cable systems

“…According to [1,2] trends of PD repetition rate and average charge per cycle, j−q−n patterns based on phase-resolved PDs have useful information for lifetime identifications.…”