Space Charge Modulated Electrical Breakdown of Oil Impregnated Paper Insulation Subjected to AC-DC Combined Voltages

Zhu, Yuanwei; Li, Shengtao; Min, Daomin; Li, Shijun; Cui, Huize; Chen, George

doi:10.3390/en11061547

Cited by 9 publications

(9 citation statements)

References 24 publications

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“…Based on the recently developed high-resolution space-charge detection methods such as pulsed electroacoustics (PEA) and pressure wave propagation (PWP), the existence, profile and functions of space charges on insulation discharge have been realized [ 16 , 17 , 18 , 19 ]. DC high voltage induces continuous space-charge injection and accumulation, which trigger increased electric field strength in the middle bulk, leading to breakdown of the insulating film [ 14 , 15 , 17 , 20 , 21 ].…”

Section: Introductionmentioning

confidence: 99%

Surface Modification-Dominated Space-Charge Behaviors of LDPE Films: A Role of Charge Injection Barriers

Zhu

Chen²,

Chen³

et al. 2022

Materials

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Gradually increasing power transmission voltage requires an improved high-voltage capability of polymeric insulating materials. Surface modification emerges as an easily accessible approach in enhancing breakdown and flashover performances due to the widely acknowledged modification of space-charge behaviors. However, as oxidation and fluorination essentially react within a limited depth of 2 μm underneath polymer surfaces, the nature of such bulk space-charge modulation remains a controversial issue, and further investigation is needed to realize enhancement of insulating performance. In this work, the surface oxidation-dependent space-charge accumulation in LDPE film was found to be dominated by an electrode/polymer interfacial barrier, but not by the generation of bulk charge traps. Through quantitative investigation of space-charge distributions along with induced electric field distortion, the functions of surface oxidation on the interfacial barrier of a typical dielectric polymer, LDPE, is discussed and linked to space-charge behaviors. As the mechanism of surface modification on space-charge behaviors is herein proposed, space-charge accumulation can be effectively modified by selecting an appropriate surface modification method, which consequentially benefits breakdown and flashover performances of polymeric insulating films for high-voltage applications.

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Section: Introductionmentioning

confidence: 99%

Surface Modification-Dominated Space-Charge Behaviors of LDPE Films: A Role of Charge Injection Barriers

Zhu

Chen²,

Chen³

et al. 2022

Materials

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“…The oil-paper insulation system is the main insulation of the converter transformer, and its performance determines the service life of the converter transformer [1]. The space charge accumulation of the oil-paper insulation system is obvious due to the influence of the DC electric field [2,3]. The existence of a space charge will cause electric field distortion and accelerate the ageing of the oil-paper insulation system.…”

Section: Introductionmentioning

confidence: 99%

Effect of multi‐factors on heterocharges for oil‐impregnated paper in converter transformer using modified charge transport model

Yan

Liu

Fan

et al. 2021

IET Generation Trans & Dist

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The heterocharge accumulated in the oil-paper insulation system of the converter transformer will enhance the local electric field and cause insulation deterioration. Numerical simulation is an effective method to analyze heterocharge. Currently, the numerical simulation of heterocharge is mainly based on the bipolar charge transport (BCT) model and the impurity ion transport (IIT) model. However, the effects of temperature, conductivity, and thickness of oil-impregnated paper on charge transport have not been considered in these models. In view of this, a modified charge transport (MCT) model by introducing the Maxwell-Wagner model and heat conduction equation is proposed in this paper based on the BCT model and IIT model. Then, the influence of multi-factors (temperature gradient, moisture content, and oil-impregnated paper thickness) on heterocharge accumulation is investigated by using the MCT model. The simulation results obtained by the MCT model are more consistent with the experimental results than the BCT model, which proves the accuracy and superiority of the MCT model. Moreover, the increase in temperature gradient, moisture content, and oil-impregnated paper thickness will enlarge the ion dissociation rate, conductivity, and trap density, and thus promote the generation of heterocharge. In that respect, the MCT model is expected to optimize the insulation design and provide a reference for space charge dynamic simulation.

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“…A common problem is that, under high voltages, space charges are formed through thermal emission and the tunneling effect, which accumulate on the surface of and inside the insulating polymer. These excessive space charges cannot dissipate as the high voltage is continuously stressed, and may form a local charge concentration, which generates a strong distorted electric field, consequently leading to partial discharge, and even breakdown [ 14 , 15 , 16 , 17 ]. Thus, discovering the accumulation of space charges at an early stage is vital for ensuring the stable operation of power equipment [ 18 ].…”

Section: Introductionmentioning

confidence: 99%

Electrochromism of Viologen/Polymer Composite: From Gel to Insulating Bulk for High-Voltage Applications

Nie¹,

Zhang

Zhu

et al. 2021

Materials

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Power equipment operates under high voltages, inducing space charge accumulation on the surface of key insulating structures, which increases the risk of discharge/breakdown and the possibility of maintenance workers experiencing electric shock accidents. Hence, a visualized non-equipment space charge detection method is of great demand in the power industry. Typical electrochromic phenomenon is based on redox of the material, triggered by a voltage smaller than 5 V with a continuous current in μA~mA level, which is not applicable to high electric fields above 106 V/m with pA~nA operation current in power equipment. Until now, no naked-eye observation technique has been realized for space charge detection to ensure the operation of power systems as well as the safety of maintenance workers. In this work, a viologen/poly(vinylidene fluoride-co-hexafluoropropylene)(P(VDF–HFP)) composite is investigated from gel to insulating bulk configurations to achieve high-voltage electrical-insulating electrochromism. The results show that viologen/P(VDF–HFP) composite bulk can withstand high electric fields at the 107 V/m level, and its electrochromism is triggered by space charges. This electrochromism phenomenon can be visually extended by increasing viologen content towards 5 wt.% and shows a positive response to voltage amplitude and application duration. As viologen/P(VDF–HFP) composite bulk exhibits a typical electrical insulating performance, it could be attached to the surface of insulating structures or clamped between metal and insulating materials as a space charge accumulation indicator in high-voltage power equipment.

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Space Charge Modulated Electrical Breakdown of Oil Impregnated Paper Insulation Subjected to AC-DC Combined Voltages

Cited by 9 publications

References 24 publications

Surface Modification-Dominated Space-Charge Behaviors of LDPE Films: A Role of Charge Injection Barriers

Surface Modification-Dominated Space-Charge Behaviors of LDPE Films: A Role of Charge Injection Barriers

Effect of multi‐factors on heterocharges for oil‐impregnated paper in converter transformer using modified charge transport model

Electrochromism of Viologen/Polymer Composite: From Gel to Insulating Bulk for High-Voltage Applications

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