High Voltage最新文献

{"title":"Insulator defect detection under extreme weather based on synthetic weather algorithm and improved YOLOv7","authors":"Yong Yang,&nbsp;Shuai Yang,&nbsp;Chuan Li,&nbsp;Yunxuan Wang,&nbsp;Xiaoqian Pi,&nbsp;Yuxin Lu,&nbsp;Ruohan Wu","doi":"10.1049/hve2.12513","DOIUrl":"https://doi.org/10.1049/hve2.12513","url":null,"abstract":"<p>Efficient and accurate insulator defect detection is essential for maintaining the safe and stable operation of transmission lines. However, the detection effectiveness is adversely impacted by complex and changeable environmental backgrounds, particularly under extreme weather that elevates accident risks. Therefore, this research proposes a high-precision intelligent strategy based on the synthetic weather algorithm and improved YOLOv7 for detecting insulator defects under extreme weather. The proposed methodology involves augmenting the dataset with synthetic rain, snow, and fog algorithm processing. Additionally, the original dataset undergoes augmentation through affine and colour transformations to improve model's generalisation performance under complex power inspection backgrounds. To achieve higher recognition accuracy in severe weather, an improved YOLOv7 algorithm for insulator defect detection is proposed, integrating focal loss with SIoU loss function and incorporating an optimised decoupled head structure. Experimental results indicate that the synthetic weather algorithm processing significantly improves the insulator defect detection accuracy under extreme weather, increasing the mean average precision by 2.4%. Furthermore, the authors’ improved YOLOv7 model achieves 91.8% for the mean average precision, outperforming the benchmark model by 2.3%. With a detection speed of 46.5 frames per second, the model meets the requirement of real-time detection of insulators and their defects during power inspection.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 1","pages":"69-77"},"PeriodicalIF":4.4,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12513","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DC allowable electric field strength for naphthenic-based and paraffin-based transformer oils","authors":"Chunjia Gao,&nbsp;Bo Qi,&nbsp;Binhao Chen,&nbsp;Juzhen Wu,&nbsp;Chengrong Li","doi":"10.1049/hve2.12506","DOIUrl":"https://doi.org/10.1049/hve2.12506","url":null,"abstract":"<p>Currently, the design of transformers insulation predominantly depends on the allowable alternating current (AC) field values for insulating oil established by Weidmann in the 1980s, lacking the research under direct current (DC) voltage for converter transformers. This study selects naphthenic oils and paraffin-based oil transformer oil as research subjects, establishing a practical measurement platform to ascertain the oil breakdown characteristics under DC voltage. Furthermore, it statistically analyses the allowable DC field values of the oil. The findings elucidate that (1) the three-parameter Weibull distribution is more suitable to conduct a statistical analysis for oil breakdown probability, yielding a fitting degree up to 99.95%. (2) For a constant electrode spacing, a 14.81% voltage increment escalates the breakdown probability of the oil gap from 3.33% to 73.33%. Concurrently, an increase in electrode spacing leads to a substantial decrement in the breakdown field strength of transformer oil, with KI25X experiencing a 54.51% reduction as electrode spacing extends from 5 to 25 mm. (3) The constant terms of the allowable DC field strength for S4, KI50X, and KI25X are found to be 19.728, 17.221, and 19.281, respectively. (4) A thorough analysis for differences in physicochemical properties and electrical parameters elucidates the variations in insulation properties across different transformer oils. The findings presented in this study offer essential theoretical and technical foundations for the design, evaluation, and enhancement of insulation structures in converter transformers.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 3","pages":"760-772"},"PeriodicalIF":4.4,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12506","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144520288","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adhesion characteristics of carbon particles on the surface of epoxy resin in insulating oil under DC electric field and influencing factors","authors":"Zijian Dong,&nbsp;Zhanlong Zhang,&nbsp;Jiarong Zhong,&nbsp;Zhixuan Xue,&nbsp;Yu Yang,&nbsp;Zhicheng Pan,&nbsp;Jin Fang","doi":"10.1049/hve2.12499","DOIUrl":"https://doi.org/10.1049/hve2.12499","url":null,"abstract":"<p>The adhesion of carbon particles on the surface of epoxy resin in insulating oil is a significant factor contributing to surface flashover. However, there is currently a lack of a dynamic model that can reasonably explain the adhesion process of impurity particles, and the characteristics of particle adhesion are not yet clear, making it difficult to assess the risks of insulation contamination and surface flashover of valve-side bushing capacitance core. In this study, based on the Johnson–Kendall–Roberts (JKR) theory and the normal distribution characteristics of particle charges, the adhesion probability model of conductive particles in insulating oil on the surface of epoxy resin under DC electric fields was established, and carbon particle adhesion experiments were conducted to verify the accuracy of the model. The impact of electric field intensity, particle size, particle charge, and surface energy of the insulation material on the adhesion characteristics of carbon particles was investigated using the proposed model. The results can be utilised for the assessment of insulation contamination risks of valve-side bushing capacitance core and serves as a vital theoretical foundation for guiding the optimisation of anti-contamination structures in internal insulation and the development of advanced pollution-resistant and flashover-resistant insulation materials.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 2","pages":"505-516"},"PeriodicalIF":4.4,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12499","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143892846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of nanostructured SiO2 on charge capture performance and electrical ageing life of PP nanocomposites","authors":"Junguo Gao,&nbsp;Liwei Liu,&nbsp;Guangwei Zhang,&nbsp;Tingtai Lee,&nbsp;Uwe Schachtely,&nbsp;Hitoshi Kobayashi","doi":"10.1049/hve2.12509","DOIUrl":"https://doi.org/10.1049/hve2.12509","url":null,"abstract":"<p>To guarantee the reliability of high-performance and environmentally friendly novel polypropylene (PP) for use as the primary insulation in cables, an assessment of the electrical ageing life of SiO₂/PP composite materials was carried out using a step-stress accelerated ageing test based on the inverse power law. The study involved an analysis of microstructural characteristics and performance testing to investigate the bonding between the SiO₂ under different surface treatment methods and matrixes. Furthermore, the impact of SiO₂ on charge capture performance in PP insulation was analysed through polarisation–depolarisation current testing. The results show that silica with long alkane chains and amino groups grafted on the surface has good compatibility with PP insulating layers, which can increase the trap energy level of captured electrons and thus reduce the damage of high-energy electrons to the composites. SiO₂ increased the life index of the PP insulating layer by 19.95%, which contributed to the improvement of the electrical ageing life of the PP insulating layer.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 1","pages":"186-196"},"PeriodicalIF":4.4,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12509","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143536064","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fast evaluation on the fatigue level of copper contact wire based on laser induced breakdown spectroscopy and supervised machine learning for high speed railway","authors":"Wenfu Wei,&nbsp;Langyu Xia,&nbsp;Zefeng Yang,&nbsp;Huan Zhang,&nbsp;Like Pan,&nbsp;Jian Wu,&nbsp;Guangning Wu","doi":"10.1049/hve2.12492","DOIUrl":"https://doi.org/10.1049/hve2.12492","url":null,"abstract":"<p>High-strength copper contact wire is of great significance to the electrified railway power supply system, which constantly provides electric power to the trains during operation. However, contact wire is subject to pressure, vibration, and natural forces such as wind, rain, ice, etc. which inevitably result in mechanical fatigue over time. This mechanical fatigue can lead to a decrease in the mechanical strength of the contact wire, and ultimately lead to problems such as wire detachment, fracture, or breakage, posing a serious safety hazard to the electrified railway system. Herein, the authors propose a strategy using nanosecond pulsed laser induced breakdown spectroscopy (LIBS) combined with machine learning technique to realise a fast evaluation on the fatigue level of copper contact line. Three different fatigue levels of copper samples have been made related with the requirement of operational conditions, and a total of 898 LIBS spectra were collected. Twenty-four combinations of spectral pre-processing, feature extraction, and optimisation algorithms were used to compare the recognition results with the accuracy, recall rate, and time cost taken into accounted. Results have shown that the standard normal variable transform–principal component analysis–genetic algorithm improve support vector machine (SNV-PCA-GASVM) model have presented a most satisfactory performance than the others. The cross-validation accuracy of the SNV-PCA-GASVM model was 92.97% while the dimensionality of input variables was reduced by 99.62%. This work is useful for the safety operation of power supply system in high speed railway, and technique development concerning the fast evaluation on materials fatigue in other industrial fields.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1302-1310"},"PeriodicalIF":4.4,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12492","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143252958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A novel thyristor-based hybrid DC circuit breaker with short arcing capability","authors":"Guanlong Jia,&nbsp;Yuchen Yuan,&nbsp;Hongjiang Guo,&nbsp;Xiaoxue Wang,&nbsp;Feng Niu","doi":"10.1049/hve2.12496","DOIUrl":"https://doi.org/10.1049/hve2.12496","url":null,"abstract":"<p>Multi-terminal flexible high-voltage direct current (HVDC) transmission and DC grid technology are developing rapidly. The hybrid DC circuit breaker (HCB) has broad application prospects in the field of HVDC transmission and DC power grid. Nevertheless, existing HCBs have one or more following blemishes: arc suppression scheme of mechanical switch, high cost and unreliable adaptive reclosure. In this paper, a modified thyristor-based hybrid DC circuit breaker with short arcing capacity (SA-HCB) is introduced, which consists of the main branch, the fault handling branch and the pre-charging branch. Besides, the modified SA-HCB has the inherent capability of adaptive reclosing. The advantages of thyristors are fully used in the SA-HCB, such as low cost, low conduction voltage drop, and natural shutdown. The detailed structure diagram and mathematical model of the SA-HCB are introduced, and the operation processes of the fault current transfer are also analysed. Later, a design method for parameters of the proposed SA-HCB is provided. Then, a single-ended equivalent system is built in PSCAD/EMTDC to verify the accuracy of the theoretical analysis and parameter design. Subsequently, based on four-terminal simulation, the economy of the SA-HCB is verified by comparing with the topology proposed by ABB. Finally, the small-scale experiment of the proposed SA-HCB is introduced.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1288-1301"},"PeriodicalIF":4.4,"publicationDate":"2024-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12496","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143252957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on influence of double energy absorptions on dynamic volt-ampere characteristics of metal oxide varistors","authors":"Chen Long,&nbsp;Yifei Wu,&nbsp;Yi Wu,&nbsp;Mingzhe Rong,&nbsp;Yu Xiao,&nbsp;Yunfan Bai","doi":"10.1049/hve2.12495","DOIUrl":"https://doi.org/10.1049/hve2.12495","url":null,"abstract":"<p>Metal oxide varistors (MOVs) are extensively employed in DC circuit breakers (DCCBs) to suppress overvoltage, dissipate energy and build up voltage after interruption. Despite their widespread use, the performance of MOVs under short-time, double energy absorption conditions is not well understood, posing a challenge to their application in open-close-open (OCO) operations of DCCBs. In this paper, a MOV double energy absorption test platform is established to investigate the deviation in volt-ampere characteristic. The Fréchet distance is proposed as the criterion for assessing the similarity of MOV dynamic volt-ampere characteristics, and the influencing factors are studied. It is observed that a 15% increase in the absorption of rated energy may result in roughly 20-unit rise in the Fréchet distance. Furthermore, the deviation in volt-ampere characteristics during the second pulse is found to be independent of the time interval, affirming that the OCO operation within 300 ms constitutes an adiabatic process. The excursion of the volt-ampere characteristics is dominated by the energy and remains unaffected by the peak current of the initial pulse. These findings lay the foundation for the subsequent MOV dynamic characteristic balance test and model modification.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 1","pages":"78-87"},"PeriodicalIF":4.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12495","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535797","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection of characteristic component H2S in SF6 and SF6/N2 mixture using cavity ring-down spectroscopy","authors":"Anhao Jiang,&nbsp;Chaohai Zhang,&nbsp;Min Zhu,&nbsp;Xiaoxing Zhang","doi":"10.1049/hve2.12508","DOIUrl":"https://doi.org/10.1049/hve2.12508","url":null,"abstract":"<p>A high-sensitivity cavity ring-down spectroscopy gas detection system with integrated optical components and embedded microprocessor units is presented for the detection of hydrogen sulfide (H₂S) in sulphur hexafluoride (SF₆) and its mixture with nitrogen (N₂). The system exploits a periodic laser wavelength modulation to simplify the mode matching. Spectral line profile fitting is used for sample quantitative analysis. To verify the sensitivity and stability of concentration detection, the effect of background gas and temperature on the responses of spectral line broadening and absorption cross-section are investigated. The result deviation caused by variation of background gas can be compensated by the pre-correction of empty cavity ring-down time. It is also found that the implication of temperature on the spectra cannot be ignored. The full width at half maximum and peak value decreased linearly with the increase of temperature, while the baseline is undergoing accelerated growth. Using Allan variance analysis, the limits of detection reach 4.44 × 10⁻⁹ in SF₆ and 2.96 × 10⁻⁹ in N₂ with average time of 67 s. This study provides a meaningful approach for the online detection of characteristic gas in gas insulation equipment.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 1","pages":"88-94"},"PeriodicalIF":4.4,"publicationDate":"2024-12-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12508","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143535931","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of excessive sheath currents in multiple cable circuits bonded to the same grounding grid","authors":"Gen Li,&nbsp;Wenjun Zhou,&nbsp;Chengke Zhou,&nbsp;Hang Wang,&nbsp;Chen Pan","doi":"10.1049/hve2.12503","DOIUrl":"https://doi.org/10.1049/hve2.12503","url":null,"abstract":"<p>In urban power networks, a common practice is to bond numerous high-voltage cable circuits to a single grounding grid located in underground tunnels, primarily for reasons of installation convenience. In these situations, excessively high levels of sheath currents were often detected during routine inspections, but no electrical faults were found to be responsible. Previous publications ignored the currents flowing through the shared grounding points into the closed sheath loops of different circuits. In this paper, a mathematical model is established for the current circulating among sheath loops of different circuits, and the factors influencing the circulating current were analysed. The abnormal excessive sheath current is demonstrated to be an increase in the circulating current due to the combined effect of electromagnetic coupling and the shared grounding grid. The circulating current depends on the induced voltages which, in turn, depends on the cable layouts and load currents. The effects of these factors are evaluated in various scenarios. The increase of the circulating current is verified in a field case where four electrically healthy cable circuits sharing the same grounding points were found to have abnormal excessive sheath currents.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"10 3","pages":"689-698"},"PeriodicalIF":4.4,"publicationDate":"2024-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12503","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144519847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Discharge image reconstruction and frequency domain analysis based on event data","authors":"Quan Yuan,&nbsp;Lei Deng,&nbsp;Hao Guo,&nbsp;Qishen Lyu,&nbsp;Xin Zhang,&nbsp;Jibin Wu,&nbsp;Yu Deng,&nbsp;Hongyang Zhou,&nbsp;Xilin Wang,&nbsp;Zhidong Jia","doi":"10.1049/hve2.12498","DOIUrl":"https://doi.org/10.1049/hve2.12498","url":null,"abstract":"<p>Optical image method has been the earliest and most used direct method for observing gas discharge. Currently, research on gas discharge monitoring based on visible light mainly relies on high-speed cameras, but the large size, significant data storage requirements, and susceptibility to interference from complex backgrounds and lighting conditions limit their further application. Dynamic vision sensing (DVS) technology is a neuromorphic sensing technology that asynchronously measures the luminance changes at each pixel. It offers advantages such as a large dynamic range (&gt;120 dB), high temporal resolution (up to 1 µs), and small data volume (MB level). In this study, dynamic vision sensing technology was employed to monitor both 30 mm short-gaps and 1080 mm long-gaps discharge processes simultaneously. This study developed the CountImage encoding method for event data and conducted image reconstruction, time-domain analysis, and frequency-domain characteristic analysis based on the event data. The results show that the event-reconstructed images are highly consistent with the high-speed camera images, and the arc development process and its path can also be clearly observed. Additionally, this study discovered a correlation between the electrical characteristics and event information during the discharge process. In the time domain, the duration of the maximum DVS event count closely matches the duration during which the voltage drops to zero during flashover. In the frequency domain, the Pearson correlation coefficient between the event stream spectrum and the voltage signal spectrum is greater than 0.95. Both the maximum number of brightening events (<i>ON</i>_max) and the maximum number of darkening events (<i>OFF</i>_max) are positively correlated with the voltage applied between the electrodes. This study demonstrates that, compared to the GB/s data rate of high-speed cameras, this approach can record the discharge process and accurately reconstruct the discharge process, arc morphology, and discharge path at MB/s data rates, while also adapting to changes in brightness without the need for exposure adjustment. Additionally, there is a positive correlation between the frequency-domain characteristics of the event data and the voltage characteristics. These results indicate that dynamic vision sensing holds promise as a replacement for high-speed cameras in laboratory discharge observations and could be even effectively applied to discharge monitoring in electrical equipment in real grid.</p>","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"9 6","pages":"1195-1201"},"PeriodicalIF":4.4,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1049/hve2.12498","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143252728","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}