{"title":"Evaluation of Moisture Ageing Status of Cross-Linked Polyethylene Insulation in Power Cables at Different Temperatures","authors":"Wen Luo, Rui Lan, Xingda Li, Guochang Li, Yanhui Wei, Shengtao Li, Yubing Duan, Qingwen Xu","doi":"10.1049/hve2.70068","DOIUrl":"https://doi.org/10.1049/hve2.70068","url":null,"abstract":"Cross-linked polyethylene (XLPE) cables play an important role in power systems to transport electrical energy, and moisture is one of the important predisposing factors for insulation failure in medium and high-voltage cables. In this paper, a temperature-moisture accelerated ageing experiment is designed, and a method for assessing the moisture status of cable insulation is proposed. This is achieved by analysing the frequency-domain dielectric-spectral curves of samples exposed to different levels of moisture and calculating the integral value of the tangent angle of the low-frequency (0.1–1 Hz) dielectric loss as the characteristic parameter. Firstly, according to the principle of time–temperature superposition, the reduced relationship model between ageing time and ageing temperature is established. Secondly, the experimental data are analysed by nonlinear regression method, and the intrinsic relationship between ageing time, temperature, moisture content and ageing characteristic quantity is established, respectively. Based on the above results, the temperature–moisture coupling coefficient is further revised, and the equation of the ageing status of XLPE insulated cables under the two-factor coupling of temperature-dampness is established. Lastly, the accuracy of the model is verified by using laboratory ageing samples and returned cables. The results indicate that the model achieves an accuracy of 95.49% under controlled laboratory conditions. Then the service life of the returned cable is quantitatively analysed, and the calculated results are within the range of the model. This work has important guiding significance for the assessment of ageing status of power cables.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"29 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089923","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Thermal Conductive Network Construction and Enhanced Thermal Conductivity in Mica Tape Composites for Large Generators by Pre-Placed h-BN@PDA-Modified Mica Paper","authors":"Zhonghua Zhang, Yu Feng, Xuesong Chen, Dongyue Wang, Zhanyi Wang, Liang Liang, Dong Yue, Qingguo Chen","doi":"10.1049/hve2.70043","DOIUrl":"https://doi.org/10.1049/hve2.70043","url":null,"abstract":"The lower thermal conductivity (TC) of mica tape hinders the evolution of large generators towards higher voltage and capacity. To enhance the TC of the mica tape, with the help of the three-dimensional (3D) multi-layer framework of the mica paper, a 3D polydopamine-coated boron nitride (h-BN@PDA) TC network was constructed by pre-placing h-BN@PDA inside the mica paper. Additionally, the above mica paper and epoxy-impregnated glass fabric were pressed to manufacture mica tape composites. Although the h-BN percentage remained constant, the TC of the h-BN@PDA/mica paper (or tape) composites could be further enhanced by depositing PDA over the h-BN surface. The TC of the 25wt.% h-BN@PDA/mica paper and mica tape composites reached 1.12 and 0.435 W/(m·K), which were 169.23% and 83.5% in comparison to pure mica paper and mica tape, respectively, also higher than those of the 25wt.% h-BN/mica paper and mica tape composites (1.07 and 0.416 W/(m·K), respectively). As calculated from theoretical modelling, this enhancement is due to the ability of the PDA coating to act as a ‘bridge’ to reduce the interfacial thermal resistance (ITR). In conclusion, the 3D TC network construction method in this research offers a new concept and strategy for manufacturing high-TC mica tapes.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"1 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Insulation Resilience Response in High-Voltage Power Equipment: Theories, Methods and Application Guidelines","authors":"Xize Dai, Jian Hao, Alberto Rumi, Claus Leth Bak, Ruijin Liao","doi":"10.1049/hve2.70102","DOIUrl":"https://doi.org/10.1049/hve2.70102","url":null,"abstract":"The multifrequency voltage (MFV) stress, including switching impulses and harmonics, commonly appearing in the modern power system will stimulate the multifrequency impedance dynamics behaviours of electrical insulation. Therefore, this article presents a novel concept of insulation resilience response (IRR) by employing polymer insulation materials, which may be extended to electrical insulation resilience (EIR). The focus is on understanding reversible recovery performance and supporting physics-informed condition assessment for electrical insulation exposed to MFV. The underlying physical mechanisms and modelling methodologies are integrated to characterise the IRR behaviours of polymer insulation systems. The multifrequency dielectric/impedance properties of different resin dielectrics under diverse temperatures are comparatively investigated as proof-of-concept cases. Furthermore, multidimensional sensitivity indicators are developed to quantify the electrical insulation resilience behaviour. A radar plot representation integrating resilience sensitivity indicators qualitatively assesses the IRR behaviours of polymer insulation systems. Additionally, a quantification methodology, including the resilience index (RI) and time-varied RI (TVRI), is proposed for the reversible recovery performance analysis for electrical insulation, respectively. Ultimately, an application-oriented framework derived from TVRI is provided to analyse the recovery performance evolution behaviours of electrical insulation under complex operating conditions. This offers a key theoretical foundation for insulation performance characterisation and condition analysis for high-voltage power equipment.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"7 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089932","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2025-09-18DOI: 10.1049/hve2.70103
Heyu Wang, Zhonglei Li, Guoning Sun, Boxue Du
{"title":"Optical Imaging-Based 3D Reconstruction of Electrical Tree in Polypropylene Cable Insulation Under Mechanical Bending","authors":"Heyu Wang, Zhonglei Li, Guoning Sun, Boxue Du","doi":"10.1049/hve2.70103","DOIUrl":"https://doi.org/10.1049/hve2.70103","url":null,"abstract":"This study proposes a nondestructive optical imaging-based three-dimensional (3D) reconstruction method to analyse electrical tree propagation in polypropylene (PP) cable insulation under mechanical bending. The technique combines focus-stacked optical imaging with a feature fusion algorithm to segment in-focus regions across depth layers, enabling 3D reconstruction of electrical trees in PP homopolymer (PPH), block copolymer (PPB) and elastomer-blended (PP/TPE) samples. The results demonstrate that mechanical bending accelerates electrical tree propagation in PPH, and that degradation channels transition from a branch-like to a straight-stick morphology, tending to grow directionally towards stretched regions. With a bending radius of 10 mm, the breakdown time drops from 297.0 min for the undeformed samples to 6.3 min. PPB and PP/TPE delay the time to breakdown by 70.6% and 171.2%, respectively, highlighting their superior resistance under bending stress, which is attributed to maintaining elasticity rather than yield deformation under bending stresses. This study provides a novel tool for evaluating the electrical tree resistance of PP composites under the mechanical stress, guiding the development of recyclable high-voltage direct current cable insulation.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"40 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2025-09-17DOI: 10.1049/hve2.70084
Gian Carlo Montanari, Sukesh Babu Myneni, Grazia Berardi, Marco Albertini, Stefano Franchi Bononi
{"title":"Investigating New Approaches for Optimal Energisations of DC Cables: The Stepwise Energisation Technique","authors":"Gian Carlo Montanari, Sukesh Babu Myneni, Grazia Berardi, Marco Albertini, Stefano Franchi Bononi","doi":"10.1049/hve2.70084","DOIUrl":"https://doi.org/10.1049/hve2.70084","url":null,"abstract":"This paper focuses on the energisation of high voltage DC (HVDC) and medium voltage DC (MVDC) insulation systems, referring mainly to cables for both theoretical development and validation testing. Cable system energisation can be frequent during its lifetime, and it can possibly be affected by partial discharges (PD), because of manufacturing, laying, ageing, interfaces or structural cavities (as butt gaps). A theory-driven and measurement-based procedure is presented in this paper, having the purpose to minimise PD inception risk. This procedure is based on stepwise voltage application during cable energisation. The fundamental idea behind the proposed approach stems from considering that the jump voltage is the trigger of PD occurrence. Indeed, the jump voltage, and the consequent electric field variation, directly relates to AC PD inception voltage (PDIV<sub>AC</sub>). In addition, the electric field distribution in an insulation system is driven by insulation permittivity (capacitance) during voltage transients, and by conductivity in DC, thus the PDIV<sub>AC</sub> is generally smaller than DC PD inception voltage (PDIV<sub>DC</sub>). Hence, energising a DC cable by an initial step lower than PDIV<sub>AC</sub>, and then increasing the voltage in steps smaller than PDIV<sub>AC</sub>, would minimise the risk of PD inception during transients and the relevant degradation rate. However, this does not change, the risk of occurrence (if any) of low-repetition partial discharges at DC steady state. Effectiveness of the proposed technique is proved by the help of tests performed on cables with artificial surface and internal defects. It is shown that compared with the conventional energisation consisting of rapidly increasing voltage, the stepwise approach can reduce the risk of PD inception and related extrinsic ageing, even for the steady state voltages larger than PDIV<sub>DC</sub>.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"89 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089312","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2025-09-15DOI: 10.1049/hve2.70096
Yoshimichi Ohki, Naoshi Hirai, Yasuhiro Tanaka
{"title":"Effects of Exposure to Radiation and Steam on Silicone Rubber Cables Removed From a Nuclear Power Plant","authors":"Yoshimichi Ohki, Naoshi Hirai, Yasuhiro Tanaka","doi":"10.1049/hve2.70096","DOIUrl":"https://doi.org/10.1049/hve2.70096","url":null,"abstract":"Low-voltage cables insulated with silicone rubber were harvested from three locations in the primary containment vessel of a boiling water nuclear power plant (NPP). Subsequently, the cable, which was placed in an ambient environment with a relatively higher temperature and the highest rate, was cut into four shorter ones. These cables were subjected to several treatments simulating design basis accident conditions, which included irradiation with gamma rays and exposure to water steam. For these cables and those harvested from the NPP, the leakage current through each cable insulation was measured with the current integration method. Consequently, all the leakage currents measured for the three cables harvested from the NPP and those treated to simulate the designed accidents are very low. Therefore, it is evident that the cables harvested from the NPP maintain good insulation integrity, even when subjected to simulated degradation.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"3 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089313","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2025-09-15DOI: 10.1049/hve2.70085
Mohammad Hossein Mousavi, Hassan Moradi, Kumars Rouzbehi, Vijay K. Sood
{"title":"Multiterminal High-Voltage Direct Current Projects: A Comprehensive Assessment and Future Prospects","authors":"Mohammad Hossein Mousavi, Hassan Moradi, Kumars Rouzbehi, Vijay K. Sood","doi":"10.1049/hve2.70085","DOIUrl":"https://doi.org/10.1049/hve2.70085","url":null,"abstract":"Multiterminal high-voltage direct current (MT-HVDC) systems are an important part of modern power systems, addressing the need for bulk power delivery and efficient renewable energy integration. This paper provides a comprehensive overview of recent advances in MT-HVDC technology, including launched projects and ongoing initiatives. The central focus of this paper is to present a detailed review of launched MT-HVDC projects across the globe, highlighting their scale, application areas and innovative features. Furthermore, this paper provides insight into ongoing research and development efforts to push the boundaries of MT-HVDC technology towards the development of overlay HVDC grids. This paper proceeds by emphasising the importance of continued innovation and collaboration in shaping the future formation of Supergrids to achieve sustainable and interconnected energy grids. Finally, the various challenges associated with MT-HVDC systems are explored. This study should serve as a resource for researchers, engineers and policymakers involved in the energy sector, offering a comprehensive overview of the latest developments and trends in MT-HVDC technology and its impact on the evolving landscape of power transmission grids.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"27 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2025-09-15DOI: 10.1049/hve2.70055
Jingjing Yang, Kaining Hou, Hongbin Wu, Penghong Guo, Yongwei Xv, Zhiqiang Zhang, Zhaoyang Kang, Ran Zhu, Hongshun Liu, Qingquan Li
{"title":"Effect of Electrical–Thermal–Mechanical Ageing on the Partial Discharge Characteristics of Oil–Pressboard Insulation Under AC–DC Voltages","authors":"Jingjing Yang, Kaining Hou, Hongbin Wu, Penghong Guo, Yongwei Xv, Zhiqiang Zhang, Zhaoyang Kang, Ran Zhu, Hongshun Liu, Qingquan Li","doi":"10.1049/hve2.70055","DOIUrl":"https://doi.org/10.1049/hve2.70055","url":null,"abstract":"Converter transformers are the core components of ultra-high voltage (UHV) transmission systems. The main cause of faults in converter transformers is irreversible deterioration of oil–pressboard insulation under combined electrical–thermal–mechanical stress over long operating times. In this paper, the chemical characteristics of oil–pressboard insulation samples subjected to electrical–thermal–mechanical ageing for different times are studied. An image processing algorithm is used to analyse the discharge propagation characteristics of the samples under combined alternating current (AC)–direct current (DC) voltage, and the current pulse curves and phase resolved partial discharge spectrogram corresponding to the discharge images are analysed. An improved wavelet packet algorithm is used to denoise the discharge current pulse. Finally, the influence of electrical–thermal–mechanical ageing on discharge characteristics is analysed using radar charts. The condition of oil–pressboard insulation is one of the main factors determining the life expectancy of converter transformers. The results obtained here therefore have practical significance for understanding the process of insulation failure caused by accelerated ageing of oil–pressboard insulation.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"38 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The SYNTHIDIA Dataset: Synthetic Insulator Defect Imaging and Annotation","authors":"Qingzhen Liu, Yadong Liu, Yingjie Yan, Qian Jiang, Xiuchen Jiang","doi":"10.1049/hve2.70091","DOIUrl":"https://doi.org/10.1049/hve2.70091","url":null,"abstract":"Accurate and timely insulator defect detection is crucial for maintaining the reliability and safety of the power supply. However, the development of deep-learning-based insulator defect detection is hindered by the scarcity of comprehensive, high-quality datasets for insulator defects. To address this gap, the synthetic insulator defect imaging and annotation (SYNTHIDIA) system was proposed. SYNTHIDIA generates synthetic defect images in a 3D virtual environment using domain randomisation, offering a cost-effective and versatile solution for creating diverse and annotated data. Our dataset includes 22,000 images with accurate pixel-level and instance-level annotations, covering broken defect and drop defect types. Through rigorous experiments, SYNTHIDIA demonstrates strong generalisation capabilities to real-world data and provides valuable insights into the impact of various domain factors on model performance. The inclusion of 3D models further supports broader research initiatives. SYNTHIDIA addresses data insufficiency in insulator defect detection and enhances model performance in data-limited scenarios, contributing significantly to the advancement of power inspection.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"3 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089324","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
High VoltagePub Date : 2025-09-14DOI: 10.1049/hve2.70090
Hucheng Liang, Bei Chu, Boxue Du
{"title":"Nondestructive Measurement of Residual Stress on Epoxy Insulators Using Thermoelastic Method","authors":"Hucheng Liang, Bei Chu, Boxue Du","doi":"10.1049/hve2.70090","DOIUrl":"https://doi.org/10.1049/hve2.70090","url":null,"abstract":"Residual stress is inevitable in epoxy insulators, which easily leads to small cracks and even insulation breakdown during the operation of gas-insulated transmission line (GIL)/gas-insulated switchgear (GIS). This study proposes a nondestructive method to measure the residual stress on epoxy insulators using thermoelastic effects. First, the laser-induced temperature rise of the epoxy/Al<sub>2</sub>O<sub>3</sub> composite was measured under different mechanical stresses to establish a relationship between the relative temperature rise and mechanical stress. Then, the residual stress distributions on full-sized insulators were reconstructed based on the stress–temperature relationship by scanning and measuring the relative temperature rise values at distributed points. The results show that the temperature rise of the epoxy/Al<sub>2</sub>O<sub>3</sub> composite is promoted by tensile stress but inhibited by compressive stress, reflecting the impacts of mechanical stress on the thermal properties of epoxy insulators. Compressive stress is present on the outer side, whereas tensile stress is concentrated on the inner side of both basin-type and tri-post insulators, with maximum values around 30 MPa. During curing, a higher temperature on the outer side of the mould leads to a faster curing rate of the insulator than on the inner side. This, combined with the mismatch of thermal expansion coefficients between epoxy and aluminium, contributes to the generation of residual stress. The measurement results of residual stress are consistent with the theoretical analysis results, verifying the effectiveness of the proposed method and offering new insights into the measurement of residual stress.","PeriodicalId":48649,"journal":{"name":"High Voltage","volume":"76 1","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-09-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}