Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine

Accurate assessment of the aging state of transformer oil-barrier insulation is crucial for ensuring the safe and reliable operation of power systems. This study presents the development of indoor accelerated thermal aging experiments to simulate the degradation of oil-immersed barrier insulation wi...

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Main Authors: Deliang Liu, Biao Lu, Wenping Wu, Wei Zhou, Wansu Liu, Yiye Sun, Shilong Wu, Guolong Shi, Leiming Yuan
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/24/23/7485
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author Deliang Liu
Biao Lu
Wenping Wu
Wei Zhou
Wansu Liu
Yiye Sun
Shilong Wu
Guolong Shi
Leiming Yuan
author_facet Deliang Liu
Biao Lu
Wenping Wu
Wei Zhou
Wansu Liu
Yiye Sun
Shilong Wu
Guolong Shi
Leiming Yuan
author_sort Deliang Liu
collection DOAJ
description Accurate assessment of the aging state of transformer oil-barrier insulation is crucial for ensuring the safe and reliable operation of power systems. This study presents the development of indoor accelerated thermal aging experiments to simulate the degradation of oil-immersed barrier insulation within transformers. A series of samples reflecting various aging states was obtained and categorized into six distinct groups. Raman spectroscopy analytical technology was employed to characterize the information indicative of different aging states of the oil-immersed barrier insulation. The raw Raman spectra were processed using asymmetric reweighted penalty least squares to correct baseline shifts, Savitzky–Golay (S-G) smoothing to eliminate fluctuation noise, and principal component analysis (PCA) to reduce data dimensionality by extracting principal components. A support vector machine (SVM) classifier was developed to discriminate between the Raman spectra and category labels. The SVM parameters were optimized using grid search, particle swarm optimization (PSO), and genetic algorithm (GA), yielding the optimal parameters (C and gamma). Notably, the grid search method demonstrated high efficiency in identifying the best combination of SVM parameters (<b><i>c</i></b> and <b><i>g</i></b>). Comparative analyses with varying numbers of principal components in SVM classifiers revealed that incorporating an optimal subset of PCA features achieved the highest classification accuracy of 94.44% for external validation samples, with only eight samples being misclassified into adjacent categories. This study offers technical support and a theoretical foundation for the effective assessment of the aging state of oil-barrier type insulation in transformers, contributing to the advancement of condition monitoring and maintenance strategies in power systems.
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spelling doaj-art-0e7798176123481fb87f7f0d8c2b261e2024-12-13T16:31:41ZengMDPI AGSensors1424-82202024-11-012423748510.3390/s24237485Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector MachineDeliang Liu0Biao Lu1Wenping Wu2Wei Zhou3Wansu Liu4Yiye Sun5Shilong Wu6Guolong Shi7Leiming Yuan8School of Information and Engineering, Suzhou University, Suzhou 234000, ChinaSchool of Information and Engineering, Suzhou University, Suzhou 234000, ChinaSchool of Information and Engineering, Suzhou University, Suzhou 234000, ChinaSchool of Information and Engineering, Suzhou University, Suzhou 234000, ChinaSchool of Information and Engineering, Suzhou University, Suzhou 234000, ChinaCollege of Electrical and Electronic Engineering, Wenzhou University, Wenzhou 325035, ChinaSuzhou Vocational and Technical College, Suzhou 234000, ChinaSchool of Information and Computer, Anhui Agricultural University, Hefei 230036, ChinaCollege of Electrical and Electronic Engineering, Wenzhou University, Wenzhou 325035, ChinaAccurate assessment of the aging state of transformer oil-barrier insulation is crucial for ensuring the safe and reliable operation of power systems. This study presents the development of indoor accelerated thermal aging experiments to simulate the degradation of oil-immersed barrier insulation within transformers. A series of samples reflecting various aging states was obtained and categorized into six distinct groups. Raman spectroscopy analytical technology was employed to characterize the information indicative of different aging states of the oil-immersed barrier insulation. The raw Raman spectra were processed using asymmetric reweighted penalty least squares to correct baseline shifts, Savitzky–Golay (S-G) smoothing to eliminate fluctuation noise, and principal component analysis (PCA) to reduce data dimensionality by extracting principal components. A support vector machine (SVM) classifier was developed to discriminate between the Raman spectra and category labels. The SVM parameters were optimized using grid search, particle swarm optimization (PSO), and genetic algorithm (GA), yielding the optimal parameters (C and gamma). Notably, the grid search method demonstrated high efficiency in identifying the best combination of SVM parameters (<b><i>c</i></b> and <b><i>g</i></b>). Comparative analyses with varying numbers of principal components in SVM classifiers revealed that incorporating an optimal subset of PCA features achieved the highest classification accuracy of 94.44% for external validation samples, with only eight samples being misclassified into adjacent categories. This study offers technical support and a theoretical foundation for the effective assessment of the aging state of oil-barrier type insulation in transformers, contributing to the advancement of condition monitoring and maintenance strategies in power systems.https://www.mdpi.com/1424-8220/24/23/7485Raman spectroscopyoil-barrier insulationaging state assessmentbaseline correctionsupport vector machine
spellingShingle Deliang Liu
Biao Lu
Wenping Wu
Wei Zhou
Wansu Liu
Yiye Sun
Shilong Wu
Guolong Shi
Leiming Yuan
Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine
Sensors
Raman spectroscopy
oil-barrier insulation
aging state assessment
baseline correction
support vector machine
title Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine
title_full Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine
title_fullStr Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine
title_full_unstemmed Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine
title_short Assessment of the Aging State for Transformer Oil-Barrier Insulation by Raman Spectroscopy and Optimized Support Vector Machine
title_sort assessment of the aging state for transformer oil barrier insulation by raman spectroscopy and optimized support vector machine
topic Raman spectroscopy
oil-barrier insulation
aging state assessment
baseline correction
support vector machine
url https://www.mdpi.com/1424-8220/24/23/7485
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