Investigation on heterocharge accumulation in crosslinked polyethylene: Experiment and simulation

Abstract

This paper presents the pulsed electro-acoustic (PEA) measurement results of the space charge behavior in as-received and degassed crosslinked polyethylene (XLPE) plate samples. A modified bipolar charge transport model, taking into account the formation of ionic charges and the extraction barrier for electronic charges, is introduced to explain the origin of the observed heterocharge accumulation. The results show that in degassed sample, the formation of heterocharge at the anode is due to delayed extraction of injected electrons. In as-received sample, the heterocharge near the cathode is positive ionic charges, whereas that observed near the anode is caused by the combined effect of negative ions and injected electrons. It is also found in the simulation that the heterocharge amount increases with the increasing of byproducts content and extraction barrier height. The extraction barrier height at the electrodes only relates to charge amount, but has no effect on the threshold for heterocharge formation.

Characteristics of electrical tree defect during the growth period in high‐voltage DC cable under stepped DC voltage

“…8, where the charges obtained by the simulation and the experiment are both bulk charges inside the material and charges at electrodes have been eliminated. The little difference in the space charge in the middle of the material between simulation results and experiment results is due to the simplification of the charge transport model in simulation [3,13,14]. However, it can be seen that the simulation results are approximately in accordance with the experimental results, thus demonstrating the validity of the simulation model.…”

“…where C is the extraction coefficient for the charge. The model parameters, which are shown in Table 2, are based on previous works [13,14], and some have been revised. To verify the accuracy of the simulation model, the simulation and experimental results are compared with the plane-parallel electrode, where the material in the plane-parallel electrode is the same as that in the needle-plane electrode.…”

“…Hence, a simulation of the needle-plane electrode needs to be conducted. The bipolar charge transport model has been widely used in simulating the space charge in the plane-parallel electrode [13,14]. Thus, this model can be used to investigate the space charge characteristics in the needle-plane electrode, thereby enabling the effect of the charge on the tree growth to be studied based on the simulation results.…”

Study on the influencing factors of space charge dynamic behavior in XLPE insulation under alternating current electric field

“…The injection barrier height ranges from 1.1 eV to 1.27 eV. [18][19][20][21][22][23][24] The detrapping barrier height is in the range of 0.90 eV to 0.99 eV. 18-20.22-24 The magnitude range of the mobility value is 10 -16 m²V -1 s -1 to 10 -12 m²V -1 s -1 .…”

“…However, several studies have found that the movement mechanisms of positive and negative space charges are different. [20][21][22][23] Specifically, the efficiency of injection, trapping, detrapping, and the migration speed are not exactly identical, which may lead to a remnant of space charge in the insulation after a period of voltage application. This is an important reason for the accumulation of space charge during the long-term operation of the cable.…”