A Novel Online Monitoring Strategy for the Localized Grounding Insulation Defect of Converter Transformers Based on Converter Switching States Control

Lu, Geye; Zhang, Qinghao; Zheng, Dayong; Zhang, Pinjia

doi:10.1109/tpel.2022.3152670

Cited by 8 publications

(3 citation statements)

References 25 publications

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“…According to Debye equivalent circuit, when the applied excitation is DC voltage, the polarization and depolarization current can be expressed by formulas (1)- (4).…”

Section: Basic Principle Of Time-frequency Domain Dielectric Responsementioning

confidence: 99%

“…At present, the research on insulation state detection of converter transformers is mainly divided into online monitoring and offline detection. The online monitoring mainly analyzes the influence of converter transformer harmonic voltage [3], current [4], local discharge [5], and vibration [6] on the aging of main insulation and obtains the change rule of online monitoring characteristic parameters. Combined with the status data of real‐time monitoring, the fault type of the converter transformer in long‐term operation can be accurately identified.…”

Section: Introductionmentioning

confidence: 99%

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Research on assessment method for main insulation state of converter transformer based on time‐frequency domain dielectric response

Zhang¹,

Yun²,

Zhang

et al. 2023

IET Science Measure & Tech

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The converter transformer is an essential part of the DC transmission system. Compared with the traditional oil-impregnated AC transformer, the main insulation of the converter transformer bears more complex electric field aging stress during long-term operation. The influence of the proportion of AC components in the AC/DC composite electric field on insulation aging is still unclear. Therefore, a combined aging test platform of composite electric field and thermal was built in the laboratory, and accelerated aging tests of oil-paper insulation under different AC/DC ratios were carried out. Through the time-frequency domain dielectric response characteristics of oil-paper insulation, the quantitative relationship between the time-frequency domain dielectric response characteristic parameters and AC proportional coefficient in different aging stages was obtained. The results show that the influence of the AC component on the aging of the oil-impregnated pressboard is more prominent. The maximum relaxation polarization time and the maximum exponential coefficient of polarization-depolarization current (PDC) can effectively characterize the aging of oil-paper insulation. Meanwhile, to accurately assess the insulation state of the converter transformer, this paper established the equivalent dielectric relaxation model for the main insulation structure. A quantitative assessment method for moisture content and aging of oil-paper insulation based on time-frequency domain dielectric response was proposed. The influence of transformer oil conductivity, test temperature, and main insulation structure was eliminated. The effectiveness of this method was verified by comparative tests, the maximum error for DP is 20, and the maximum error for moisture content is 0.15%. The research results of this paper can provide theoretical support for on-site assessment of converter transformer insulation status.

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“…According to Debye equivalent circuit, when the applied excitation is DC voltage, the polarization and depolarization current can be expressed by formulas (1)- (4).…”

Section: Basic Principle Of Time-frequency Domain Dielectric Responsementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Research on assessment method for main insulation state of converter transformer based on time‐frequency domain dielectric response

Zhang¹,

Yun²,

Zhang

et al. 2023

IET Science Measure & Tech

View full text Add to dashboard Cite

show abstract

“…[1][2][3][4] Specifically, these defects lead to electricalstress concentration in dielectric polymers, which typically operate under an electric field for a significant period, ultimately resulting in the premature failure of materials. [5][6][7] Consequently, visualization of the electric-field distribution in solid materials is an arduous task, it is an effective approach to fundamentally address the premature failure of polymers. Therefore, it is desirable to establish a novel monitoring method enabling nondestructive and real-time defect positioning and electrical-stress visualization in polymers at the micron level.…”

Section: Introductionmentioning

confidence: 99%

Self‐Reporting Microsensors Inspired by Noctiluca Scintillans for Small‐Defect Positioning and Electrical‐Stress Visualization in Polymers

Sima,

Yang,

Sun

et al. 2024

Advanced Materials

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Abstractsmall defects induce concentrated electrical stress in dielectric polymers, leading to premature failure of materials. Existing sensing methods fail to effectively visualize these defects owing to the invisible‐energy state of the electric field. Thus, it is necessary to establish a nondestructive method for the real‐time detection of small defects in dielectric polymers. In this study, a self‐reporting microsensor (SRM) inspired by Noctiluca scintillans is designed to endow materials with the ability of self‐detection for defects and electrical stress. The SRM leverages the energy of a nearby electric field to emit measurable fluorescence, enabling defect localization and diagnosis as well as electrical‐stress visualization. A controllable dielectric microsphere is constructed to achieve an adjustable electroluminescence threshold for the SRM, thereby increasing its detection accuracy while decreasing the electroluminescence threshold. The potential degradation in the polymer performance owing to SRM implantation is addressed by assembling long molecular chains on the SRM surface to spontaneously generate an interpenetrating network. Results of finite element analyses and experiments demonstrate that the SRM can effectively realize nondestructive visualization and positioning of small defects and concentrated electrical stress in polymers, positioning it as a promising sensing method for monitoring the electric field and charge distribution in materials.This article is protected by copyright. All rights reserved

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Study on Variable Frequency Power Supply Cable and Leakage Current Characteristics of High-Speed Maglev Train

Li,

Du,

Guo

et al. 2024

Lecture Notes in Electrical Engineering

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A Novel Online Monitoring Strategy for the Localized Grounding Insulation Defect of Converter Transformers Based on Converter Switching States Control

Cited by 8 publications

References 25 publications

Research on assessment method for main insulation state of converter transformer based on time‐frequency domain dielectric response

Research on assessment method for main insulation state of converter transformer based on time‐frequency domain dielectric response

Self‐Reporting Microsensors Inspired by Noctiluca Scintillans for Small‐Defect Positioning and Electrical‐Stress Visualization in Polymers

Study on Variable Frequency Power Supply Cable and Leakage Current Characteristics of High-Speed Maglev Train

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