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Molecular Insights Into the Effects of Thermal Oxidative Aging on the Insulation Properties of Cross-Linked Polyethylene 热氧化老化对交联聚乙烯绝缘性能影响的分子研究
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-19 DOI: 10.1109/TDEI.2025.3543802
Wenyu Ye;Chenyu Gao;Xinhan Qiao;Haolun Che;Jianwen Zhang;Jian Hao
The degradation of the insulation performance of cross-linked polyethylene (XLPE) during thermal oxidative aging is a crucial factor affecting the safe operation of cables. Investigating the influence of the structural degradation process of XLPE on its insulation properties from a molecular structure and microscopic parameter perspective can provide a better understanding of the molecular mechanisms behind insulation performance degradation during thermal oxidative aging. In this study, the reaction kinetics of XLPE were simulated using the Ab initio molecular dynamics (AIMDs), resulting in the extraction of five XLPE structures with varying degrees of aging. Density functional theory (DFT) simulations were employed to analyze the variation patterns and differences in discharge-related microscopic parameters of these five different XLPE structures under varying electric field intensities. The results show that there are significant differences in the structure and dipole moment of XLPE with different aging degrees, resulting in large changes in its microscopic parameters. In particular, the formation of carbonyl groups in XLPE has a significant impact on its structure and microscopic parameters. As the aging degree of XLPE increases, the ionization of XLPE molecules and the activity of electron affinity (EA) molecules intensify. The structural evolution of XLPE during the aging process markedly influences the excitation process and molecular orbitals of its molecules, facilitating the release of numerous photons, creating conditions for secondary electron collapse, and enhancing molecular conductivity. The simulation results of the molecular surface electrostatic potential (ESP) reveal that deeper aging of XLPE increases the likelihood of electrophilic and nucleophilic reactions, as well as electron accumulation and collision. Overall, the electric field exerts a minimal effect on the molecular structure and microscopic parameters of different XLPE molecules.
交联聚乙烯(XLPE)在热氧化老化过程中绝缘性能的下降是影响电缆安全运行的关键因素。从分子结构和微观参数的角度研究XLPE结构降解过程对其保温性能的影响,有助于更好地理解热氧化老化过程中保温性能降解的分子机制。本研究利用从头算分子动力学(AIMDs)模拟了XLPE的反应动力学,提取了5种不同老化程度的XLPE结构。采用密度泛函理论(DFT)模拟分析了不同电场强度下这5种不同XLPE结构放电相关微观参数的变化规律和差异。结果表明:不同时效程度的XLPE在结构和偶极矩上存在显著差异,导致其微观参数变化较大;特别是羰基的形成对XLPE的结构和微观参数有显著的影响。随着XLPE老化程度的增加,XLPE分子的电离和电子亲和(EA)分子的活性增强。老化过程中XLPE的结构演变显著影响了其分子的激发过程和分子轨道,促进了大量光子的释放,为二次电子坍缩创造了条件,增强了分子的电导率。分子表面静电势(ESP)的模拟结果表明,XLPE老化越深,发生亲电和亲核反应的可能性越大,电子积累和碰撞的可能性也越大。总的来说,电场对不同XLPE分子的分子结构和微观参数的影响很小。
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引用次数: 0
Analysis and Diagnosis of Optical and UHF Partial Discharges in GIS Based on Guided Filtering Fusion 基于引导滤波融合的GIS光与超高频局部放电分析与诊断
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-18 DOI: 10.1109/TDEI.2025.3543147
Ze Li;Yiming Zang;Chenglin Wang;Yanshu Tang;Tongyang Ren;Xiuchen Jiang
The optical method and ultrahigh frequency (UHF) method are important techniques for detecting partial discharge (PD) in gas-insulated switchgear (GIS). However, optical signals and UHF signals may suffer from different degrees of signal loss or interference for different PD types, which leads to incomplete feature information in the optical or UHF patterns and reduces the accuracy of pattern recognition. In this article, a PD detection device in GIS based on the UHF and light guide rod (LGR) technologies is designed. An experimental platform for electrical and optical PD detection in GIS is set up, and measurements of typical PD are carried out. Optical and UHF time-domain signals of corona discharge, floating discharge, and particle discharge are obtained. Then, an image fusion algorithm based on guided filtering fusion (GFF) is proposed to fuse the optical and UHF phase-resolved pulse sequence (PRPS) patterns. Subsequently, a feature extraction method based on speeded-up robust features (SURFs) for PD images is proposed. Finally, the recognition effects of multiple classifiers are compared. The results show that the image fusion and feature extraction method for UHF and optical PD proposed in this article can improve the accuracy of fault diagnosis up to 97.1%.
光学法和超高频(UHF)法是气体绝缘开关设备局部放电检测的重要技术。但是,对于不同的PD类型,光信号和UHF信号可能遭受不同程度的信号损失或干扰,导致光或UHF模式中的特征信息不完整,降低了模式识别的准确性。本文设计了一种基于超高频光导杆(LGR)技术的GIS局部放电检测装置。建立了GIS中光电局部放电检测的实验平台,并对典型局部放电进行了测量。得到了电晕放电、悬浮放电和粒子放电的光时域和超高频时域信号。然后,提出了一种基于制导滤波融合(GFF)的图像融合算法,用于融合光学和超高频相分辨脉冲序列(PRPS)模式。随后,提出了一种基于加速鲁棒特征的PD图像特征提取方法。最后,比较了多个分类器的识别效果。结果表明,本文提出的UHF与光学PD图像融合与特征提取方法可将故障诊断准确率提高97.1%。
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引用次数: 0
Aging Failure Mechanism of Graft Modified Polypropylene Cable Insulation 接枝改性聚丙烯电缆绝缘老化失效机理研究
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-18 DOI: 10.1109/TDEI.2025.3543154
Yunjian Wu;Danfeng Zhang;Yifan Guo;Fanwu Chu;Guangke Li;Xiaoxing Zhang
The performance of polypropylene (PP) insulation material used in high-voltage power cables is crucial for ensuring the safe and reliable operation of the cables. To deeply understand the aging and failure mechanisms of graft-modified PP cable insulation, accelerated aging experiments were conducted on the cable insulation layer. The ac breakdown field strength and elongation at break were tested, the density functional theory calculations were performed on the graft-modified PP molecular chains, and further analyses of the physicochemical properties, such as the microstructure and molecular structure changes of the insulation material, were conducted. The results show that when the insulation material reaches the aging failure point, the breakdown performance significantly decreases, the perfection of the crystalline region structure of PP deteriorates with aging time, the content of C=O carbonyl groups significantly increases with aging time, and thermal-oxidative aging accelerates the destruction of PP spherulites. The appearance of oxidation products, structure loosening, and decreased crystallinity during the aging process are the main reasons for the reduction in mechanical performance and breakdown strength. This study provides new insights into the research on the aging mechanism, structure, and performance relationship of PP cable insulation and has important guiding significance for the design of PP insulation materials.
高压电力电缆中使用的聚丙烯(PP)绝缘材料的性能对保证电缆的安全可靠运行至关重要。为深入了解接枝改性PP电缆绝缘老化失效机理,对电缆绝缘层进行了加速老化实验。测试了交流击穿场强和断裂伸长率,对接枝改性PP分子链进行了密度泛函理论计算,并进一步分析了保温材料的微观结构和分子结构变化等理化性质。结果表明:当保温材料达到老化失效点时,击穿性能显著降低,PP晶区结构的完善性随老化时间的延长而恶化,C=O羰基含量随老化时间的延长而显著增加,热氧化老化加速了PP球晶的破坏。老化过程中氧化产物的出现、组织松动、结晶度降低是导致机械性能和击穿强度下降的主要原因。本研究为PP电缆绝缘老化机理、结构及性能关系的研究提供了新的见解,对PP绝缘材料的设计具有重要的指导意义。
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引用次数: 0
Effect of the DC–AC Switching Electric Field on Surface Electrical Properties of GIS Epoxy Spacer 直流-交流开关电场对GIS环氧树脂隔层表面电学性能的影响
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-17 DOI: 10.1109/TDEI.2025.3543146
Song Yanze;Zhang Yutong;Xie Jun;Liang Guishu;Ran Huijuan;Zhong Yuyao;Xia Guowei;Zhang Minhan;Zhang Zhenli;Xie Qing
This article explores the behavior of charge transport and the surface electrical properties of epoxy spacers within high-voltage alternating current (HVac) gas-insulated switchgear (GIS), which may be exposed to the dc-ac switching electric field at the end of dc ice melting. Simulation and experimental results reveal that increasing dc voltage and duration enhances charge accumulation at the gas-solid interface, whose polarity aligns with the electrodes. When the electric field transitions to ac, charge accumulation occurs gradually during the half-cycle, where the voltage polarity matches the charge polarity. However, during the half-cycle of opposite polarity, the probability of flashover increases dramatically. Positive polarity dc charging leads to greater charge accumulation and more severe electric field distortion than negative polarity, thereby increasing the risk to the insulation performance.
本文研究了高压交流(HVac)气体绝缘开关设备(GIS)在直流融冰结束时可能暴露在直流-交流开关电场中的电荷输运行为和环氧树脂间隔层的表面电学性质。仿真和实验结果表明,增加直流电压和持续时间可以增强气固界面的电荷积累,其极性与电极一致。当电场转变为交流电时,电荷在半周期内逐渐积累,此时电压极性与电荷极性相匹配。然而,在极性相反的半周期内,闪络的概率急剧增加。正极性直流充电比负极性直流充电导致更大的电荷积累和更严重的电场畸变,从而增加了绝缘性能的风险。
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引用次数: 0
Transformer Dissolved Gas Concentration Prediction Based on Quadratic Decomposition Reconstruction and BKA-BiLSTM 基于二次分解重构和BKA-BiLSTM的变压器溶解气体浓度预测
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-14 DOI: 10.1109/TDEI.2025.3542749
Can Ding;Donghai Yu;Xianqiao Li;Daomin Min
For the prediction of each gas concentration in oil-immersed transformers, in this article, improved complete ensemble empirical mode decomposition with adaptive noise (ICEEMDAN) is first applied to the original gas data, and the sample entropy (SE) value of each subsequence is computed, the high-frequency sequences with the highest SE are subjected to quadratic variational mode decomposition (VMD) to further reduce the degree of its instability, that is, the ICEEMDAN-SE-VMD decomposition model is formed. Second, reconstruction operations are performed on the subsequences with close SE values after ICEEMDAN decomposition to reduce the prediction time while ensuring the accuracy. Finally, a bidirectional long short-term memory with attention mechanism (Bi-LSTM-AT) is used to predict each subsequence separately; for the optimization of the parameters in prediction algorithms, the latest black-winged kite algorithm (BKA) is used in this article for optimization of the parameters, and the prediction results of the subsequence are superimposed to be the final prediction value for the gas concentration. The prediction results of the six gases produced by the transformer show that compared with other methods, the prediction method used in this article reduces the prediction time, while the prediction accuracy is also guaranteed.
对于油浸式变压器中各气体浓度的预测,本文首先对原始气体数据应用改进的带自适应噪声的全系综经验模态分解(ICEEMDAN),计算各子序列的样本熵(SE)值,对SE最高的高频序列进行二次变分模态分解(VMD),进一步降低其不稳定程度,即:形成了ICEEMDAN-SE-VMD分解模型。其次,对ICEEMDAN分解后SE值相近的子序列进行重构操作,在保证预测精度的同时减少预测时间。最后,利用双向长短期记忆注意机制(Bi-LSTM-AT)分别预测每个子序列;对于预测算法中的参数优化,本文采用最新的黑翼风筝算法(BKA)对参数进行优化,并将子序列的预测结果进行叠加,得到最终的气体浓度预测值。对变压器产生的六种气体的预测结果表明,与其他方法相比,本文所采用的预测方法减少了预测时间,同时也保证了预测精度。
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引用次数: 0
Hybrid Deep Learning Models for Enhanced Classification of Phase-Resolved Partial Discharge Patterns From High-Voltage Rotating Machine Insulation 基于混合深度学习模型的高压旋转电机绝缘相位分辨局部放电模式增强分类
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-14 DOI: 10.1109/TDEI.2025.3542343
Ciptian Weried Priananda;Hazlee Azil Illias;Wong Jee Keen Raymond;I. Made Yulistiya Negara
Partial discharge (PD) monitoring plays a crucial role in identifying insulation defects in high-voltage rotating machinery, where accurate classification is essential for improving the reliability and efficiency of condition-based maintenance (CBM). This work proposes hybrid convolutional neural network (CNN) models to classify phase-resolved PD (PRPD) patterns from six different defects in a rotating machine insulation. Various hybrid models were evaluated by integrating CNN with machine learning (ML) algorithms, which include support vector machines (SVMs), k-nearest neighbors (KNNs), logistic regression (LR), decision trees (DTs), random forests (RFs), and naive Bayes (NB). The results reveal that all proposed hybrid models consistently outperform CNN in terms of computational efficiency, by achieving an average accuracy of 94.87% across all models using two optimizers, ADAM and stochastic gradient descent with momentum (SGDM). Notably, CNN-RF (CNN-RF) and CNN-KNN (CNN-KNN) models achieve the best performance, with an accuracy exceeding 96% with lower computational time compared to CNN, which only achieves 94.44% accuracy. Thus, this work provides valuable insight into enhancing PRPD classification with lower computational cost while increasing the classification accuracy of PRPD patterns from rotating machine insulation.
局部放电(PD)监测在识别高压旋转机械绝缘缺陷中起着至关重要的作用,准确分类是提高状态维修(CBM)可靠性和效率的关键。这项工作提出了混合卷积神经网络(CNN)模型,用于从旋转机器绝缘的六种不同缺陷中分类相位分辨PD (PRPD)模式。通过将CNN与机器学习(ML)算法(包括支持向量机(svm)、k近邻(KNNs)、逻辑回归(LR)、决策树(dt)、随机森林(rf)和朴素贝叶斯(NB))相结合,评估了各种混合模型。结果表明,所有提出的混合模型在计算效率方面始终优于CNN,通过使用两个优化器ADAM和随机梯度下降(SGDM),所有模型的平均准确率达到94.87%。值得注意的是,CNN- rf (CNN- rf)和CNN- knn (CNN- knn)模型的性能最好,与CNN相比,准确率超过96%,计算时间更短,准确率仅为94.44%。因此,这项工作为以更低的计算成本增强PRPD分类提供了有价值的见解,同时提高了旋转机器绝缘PRPD模式的分类精度。
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引用次数: 0
Dielectric Mechanisms and Health State Estimation for High-Voltage XLPE Cable Insulation Under Nonuniform Thermal Aging 非均匀热老化下高压交联聚乙烯电缆绝缘介电机理及健康状态评估
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-14 DOI: 10.1109/TDEI.2025.3542752
Xize Dai;Jian Hao;Mohamed El Moursi;Rongxin Chen;Ruijin Liao;Claus Leth Bak
High-voltage (HV) crosslinked polyethylene (XLPE) cables are subjected to electrothermal stress gradients during service, which often leads to nonuniform degradation within insulation systems, significantly affecting their endurance, resilience, and overall lifetime. This article presents a comprehensive study of dielectric mechanisms and health state estimation of XLPE insulation under nonuniform thermal aging, with a particular emphasis on 500-kV XLPE cables. First, the distinct effects of uniform versus nonuniform thermal aging mechanisms on XLPE systems are compared through selected five combinations in two groups. Furthermore, the mechanisms by which nonuniform thermal aging influences XLPE insulation systems are revealed using three dielectric analysis techniques. Additionally, this work innovatively introduces a quantitative framework for the health state estimation of XLPE cable insulation under nonuniform thermal aging, utilizing the previously developed equivalent circuit model that incorporates a fractional-order circuit module (FOCM). The aging features extracted from the FOCM are utilized to develop health state estimation models for XLPE insulation under different nonuniform thermal aging conditions. The performance and limitations of health estimation models are discussed using a stacked XLPE system. This study deepens the understanding of nonuniform thermal aging mechanisms and provides insights to support condition-based maintenance of HV cable insulation under complex aging conditions.
高压(HV)交联聚乙烯(XLPE)电缆在使用过程中会受到电热应力梯度的影响,这通常会导致绝缘系统内的不均匀退化,严重影响其耐久性、回弹性和整体寿命。本文以500kv交联聚乙烯电缆为研究对象,对非均匀热老化条件下交联聚乙烯绝缘的介电机理和健康状态评估进行了全面的研究。首先,通过两组中选择的五种组合,比较了均匀和非均匀热老化机制对XLPE体系的不同影响。此外,利用三种介电分析技术揭示了非均匀热老化影响XLPE绝缘体系的机理。此外,本工作创新性地引入了一个定量框架,利用先前开发的包含分数阶电路模块(FOCM)的等效电路模型,对非均匀热老化下的XLPE电缆绝缘进行健康状态估计。利用从FOCM中提取的老化特征,建立了不同非均匀热老化条件下XLPE绝缘的健康状态估计模型。利用堆叠XLPE系统讨论了健康估计模型的性能和局限性。该研究加深了对非均匀热老化机制的理解,并为复杂老化条件下高压电缆绝缘的状态维护提供了见解。
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引用次数: 0
A Temperature-Compensated CNN-Based Method for Transformer Partial Discharge Localization 基于温度补偿cnn的变压器局部放电定位方法
IF 3.1 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-13 DOI: 10.1109/TDEI.2025.3542015
Haitao Wang;Shirong Zhang
An acoustic time reversal-convolutional neural network (ATR-CNN) approach is proposed for localizing partial discharge (PD) in power transformers with temperature compensation. A digital twin model is developed through multiphysics coupling analysis to accurately describe temperature distributions in oil-immersed natural air-cooling (ONAN) transformers. The temperature-compensated dual-sensor configuration demonstrates a root-mean-square error (RMSE) of 4.48 mm in PD localization, exhibiting a minimal accuracy degradation of 1.4 mm in unseen datasets while maintaining consistent performance across noise levels (0%–10%). Comparative analyses reveal the ATR-CNN methodology’s superior localization accuracy over traditional machine learning algorithms and enhanced performance in non-line-of-sight regions compared to the time difference of arrival (TDoA) approaches. A significant 264 000-fold reduction in computation time is achieved relative to ATR implementations. Integrating deep learning with ATR techniques offers an enhanced approach to PD localization in complex transformer environments.
提出了一种基于声时逆卷积神经网络(ATR-CNN)的温度补偿电力变压器局部放电定位方法。通过多物理场耦合分析,建立了准确描述油浸式自然空冷(ONAN)变压器温度分布的数字孪生模型。温度补偿双传感器配置显示PD定位的均方根误差(RMSE)为4.48 mm,在未见过的数据集中显示最小的精度下降1.4 mm,同时在噪声水平(0%-10%)下保持一致的性能。对比分析表明,与传统机器学习算法相比,ATR-CNN方法具有更高的定位精度,并且与到达时差(TDoA)方法相比,在非视距区域具有更高的性能。与ATR实现相比,计算时间显著减少了264,000倍。将深度学习与ATR技术相结合,为复杂变压器环境中的PD定位提供了一种增强的方法。
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引用次数: 0
Analytical Model for Transient Space Charge in Low-Density Polyethylene 低密度聚乙烯中瞬态空间电荷的解析模型
IF 2.9 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-13 DOI: 10.1109/TDEI.2025.3541613
Purnabhishek Muppala;C. C. Reddy
Despite being an experimentally well-studied phenomena, a consistent lacuna has always persisted in the theoretical and mathematical understanding of space charge dynamics in low-density polyethylene (LDPE). The macroscopic models reported so far in the literature seem to be insufficient and fail to predict the formation of homo- and hetero-charges near the electrodes and transport of charge packets. On the other hand, while microscopic models such as bipolar charge transport (BCT) model were able to explain homo-charge accumulation and movement of charge packets to a limited success, they are often fraught with assumptions such as neglection of diffusion phenomena and are structurally complicated when compared to macroscopic models. In this work, the authors have derived analytical solutions for space charge dynamics based on Maxwell’s equations and transient space charge limited current (TSLC)-based volumetric current models, which take into consideration the measured absorption (slow polarization) and steady-state volumetric currents. The proposed analytical (macroscopic) model can thus predict the homo- and hetero-charge accumulation in LDPE, which is validated through comparisons with the experimentally measured space charge, wherein a remarkable agreement was observed. Furthermore, the relation between the transient volumetric current and space charge dynamics is reaffirmed.
尽管低密度聚乙烯(LDPE)的空间电荷动力学是一种实验研究很充分的现象,但在理论和数学理解上一直存在一个一致的空白。目前文献中报道的宏观模型似乎是不充分的,不能预测电极附近的同性和异性电荷的形成和电荷包的传输。另一方面,虽然微观模型(如双极电荷输运(BCT)模型)能够解释电荷包的均匀电荷积累和运动,但取得了有限的成功,但与宏观模型相比,它们往往充满了诸如忽略扩散现象等假设,并且结构复杂。在这项工作中,作者基于麦克斯韦方程和基于瞬态空间电荷限制电流(TSLC)的体积电流模型推导了空间电荷动力学的解析解,该模型考虑了测量的吸收(慢极化)和稳态体积电流。因此,所提出的分析(宏观)模型可以预测LDPE中同性和异性电荷的积累,并通过与实验测量的空间电荷的比较验证了这一点,其中观察到非常一致。并进一步确认了瞬态体积电流与空间电荷动力学之间的关系。
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引用次数: 0
Enhancing Insulator String Performance: Pollution and Icing Flashover Analysis Through Artificial Neural Network-Based Layout Optimization for Inverted T-Type String 提高绝缘子串性能:基于人工神经网络的倒t型串布局优化污染和覆冰闪络分析
IF 2.9 3区 工程技术 Q2 ENGINEERING, ELECTRICAL & ELECTRONIC Pub Date : 2025-02-13 DOI: 10.1109/TDEI.2025.3542009
Mahmoud A. Ali;Xingliang Jiang;Salah Kamel;Asad Awan
This study explores the impact of various high-voltage insulator string configurations on pollution and icing flashover characteristics under different environmental conditions. The inverted T-string design is suggested, offering improvements over the traditional I-string configuration. An experimental investigation is conducted using high-voltage glass-type disks (LD-160), along with the development of two artificial neural network (ANN) models to simulate and predict flashover voltages. The results demonstrate that the inverted T-string arrangement enhances the flashover voltage for polluted insulator strings by approximately 7% and increases the icing flashover voltage by 3.43%–5.01% compared to standard I-strings. The ANN models successfully determine optimal insulator configurations, demonstrating their potential to enhance high-voltage insulation performance with minimal experimentation. This study emphasizes the innovative use of ANN in optimizing insulator string arrangements, providing a practical solution for tackling pollution and icing issues in power systems.
本研究探讨了不同高压绝缘子串配置对不同环境条件下污覆闪络特性的影响。建议采用倒t型管柱设计,对传统的i型管柱结构进行改进。利用高压玻璃盘(LD-160)进行了实验研究,并建立了两种人工神经网络(ANN)模型来模拟和预测闪络电压。结果表明,与标准i型串相比,倒置t型串布置能使污绝缘子串的闪络电压提高约7%,使覆冰闪络电压提高3.43% ~ 5.01%。人工神经网络模型成功地确定了最佳绝缘子配置,证明了它们在以最少的实验提高高压绝缘性能方面的潜力。本研究强调人工神经网络在优化绝缘子串排列中的创新应用,为解决电力系统中的污染和结冰问题提供了一种实用的解决方案。
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引用次数: 0
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IEEE Transactions on Dielectrics and Electrical Insulation
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