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Intelligent overheating fault diagnosis for overhead transmission line using semantic segmentation

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high voltage 2024年第2期9卷 309-318页

作者： Xiangyu Yang Youping Tu Zhikang Yuan Zhong Zheng Geng Chen Cong Wang Yan Xu beijing key laboratory of high voltage and emc North China Electric Power UniversityBeijingChina College of Electronic and Information Engineering Tongji UniversityShanghaiChina

The strain clamps and leading wires are important components that connect conductors on overhead transmission lines and conduct *** operation,poor contact between these components can cause abnormal overheating,leading to electric failures and threatening power system ***,the use of unmanned aerial vehicles equipped with infrared thermal imagers for strain clamp and leading wire maintenance has become increasingly *** learning-based image recognition shows promising prospects for intelligent fault diagnosis of overheating faults.A pre-treatment method is proposed based on dynamic histogram equalisation to enhance the contrast of infrared *** DeepLab v3+network,loss function,and existing networks with different backbones are *** DeepLab v3+network with ResNet101 and convolutional block attention module added,and the Focal Loss function achieved the highest performance with an average pixel accuracy of 0.614,an average intersection over union(AIoU)of 0.567,an F1 score of 0.644,and a frequency weighted intersection over union of 0.594 on the test *** optimised Atrous rates has increased the AIoU by 12.91%.Moreover,an intelligent diagnosis scheme for evaluating the defect state of the strain clamps and leading wires is proposed and which achieves a diagnostic accuracy of 91.0%.

关键词： union fault diagnosis

Charge Accumulation Characteristics of SF6-Epoxy Interface Under Negative Repetitive Nanosecond Pulses

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CSEE Journal of Power and Energy Systems 2024年第4期10卷 1808-1815页

作者： Shaocong Wu Geng Chen Yuming Shao Hao Xu Xuanning Zhang Yanyu Liang Youping Tu State key laboratory of Alternate Electrical Power System with Renewable Energy Sources and the beijing key laboratory of high voltage and emc North China Electric Power UniversityBeijing 102206China

Repetitve nanosecond impulses in gas-insulated metal-enclosed switchgear (GIS) are likely to trigger inside flashover. Interface charges on the spacer in GIS are considered one of the main factors damaging insulation performance and may be induced by overvoltage. For good understanding of insulation failures, accumulation characteristics of charges between SF6 and epoxy spacers under repetitive nanosecond impulses are investigated. It can be found under nanosecond impulses, the charge source in gas volume contributes to interface charge accumulation predominantly. Interface charges will be promoted by impulse number and amplitude. Accumulation processes are analyzed based on runaway electrons mechanism. When impulse amplitude exceeds a threshold value, discharge in the gas volume turns to a runaway mode. A runaway electron leads to the interface charge accumulation. Affected by motion of the runaway electrons, the potential peak gradually moves close to the grounded electrode when impulse amplitude is raised. Meanwhile, increasing impulse number can enhance surface potential. Surface potential will reach saturation eventually. However, memory effect of the repetitive impulse discharge makes the half-peak width of the surface potential at the interface change little. Design of GIS gas-solid insulations can refer to this research.

关键词： GIS interface charge repetitive nano-second pulse SF6

Optical Sensor with Wide Range and high Sensitivity for Internal Magnetic Field Detection of Transformer

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 2230-2244页

作者： Meng Huang Wei Zheng Tong Ji Mao Ji Tianjiao Pu Bo Qi State key laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijing 102206China beijing key laboratory of high voltage&emc North China Electric Power UniversityBeijing 102206China China Electric Power Research Institute Beijing 100192China

The deterioration of winding defects is one of the important causes of power transformer fires and even explosion *** change of leakage magnetic field distribution is the most direct response to winding *** there are few sensors suitable for online measurement of the internal magnetic field of *** on the Faraday magneto-optical effect,a magnetic field sensor with wide range and high sensitivity is proposed in this paper,which is suitable for the interior use of *** straight-through optical structure with interior polarizer is adopted,and the sensor has a measurement range of 1.5 T and a sensitivity of 1 *** also possesses a small size,with a length of about 30 mm after *** influence mechanism of vibration and temperature is revealed through theoretical analysis and numerical *** is proposed to filter out the interference of vibration by characteristic frequency analysis and to compensate for temperature by a two-probe *** anti-interference test verifies the effectiveness of this method,and it can reduce the error from 80.56%to 2.63%under the combined interference of vibration and temperature.

关键词： Anti-interference Bessel function Faraday magneto-optical effect leakage magnetic field transformer two-probe structure

Recyclable Polypropylene-based Insulation Materials for HVDC Cables:Progress and Perspective

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CSEE Journal of Power and Energy Systems 2024年第5期10卷 2208-2220页

作者： Yao Zhou Shixun Hu Chao Yuan Jun Hu Qi Li Jinliang He State key laboratory of Power Systems Department of Electrical EngineeringTsinghua UniversityBeijing 100084China beijing key Lab of high voltage&emc and State Key Lab of Alternate Electrical Power System with Renewable Energy SourcesNorth China Electric Power UniversityBeijing 102206China.

Polypropylene(PP)-based recyclable materials have attracted tremendous interest for HVDC cable insulation applications due to their superior electrical properties,e.g.,high thermal stability and superior *** with crosslinked polyethylene(XLPE),PP-based materials exhibit the advantages of not only higher working temperatures but also facile and efficient cable manufacturing with reduced costs,which are highly desirable in HVDC cable *** their promising advantages,PP-based materials have received significant attention from both academia and industry in the field of HVDC cable *** order to adopt PP as a cable insulation material,the mechanical flexibility of PP should be ***,regulations of the mechanical properties inevitably influences the electrical properties of *** extensive research has been conducted on the regulation of the mechanical and electrical properties of *** review summarizes the research progress on recyclable PP-based materials for HVDC cable insulation *** attention is placed on the electrical property regulations and material structure-property *** challenges that remain to be addressed and the opportunities for future studies on PP-based recyclable HVDC cable insulation materials are also presented.

关键词： polypropylene HVDC cable dielectric materials recyclable insulation materials

Accelerated thermal ageing on performance of polypropylene-based semiconducting screen for high voltage direct current cable applications-Effect of antioxidants

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high voltage 2024年第2期9卷 410-418页

作者： Haitian Wang Yi Luo Mingyu Zhou Xintong Ren George Chen GEIRI BerlinGermany The Tony Davies high voltage laboratory University of SouthamptonSouthamptonUK

The potential of using eco-friendly thermoplastic polypropylene(PP)-based insulation for high voltage direct current(HVDC)cable has been widely investigated but much less work on the PP-based semiconducting screen(SC).Considering a long service life(>30 years)under high temperature and high electrical stress is required for typical HVDC cables,and investigations on the effect of antioxidant(AO)concentration and thermal oxidative sta-bility,mechanical,and electrical properties of PP-based SCs have been *** has been demonstrated that an appropriate combination and amounts of AOs are critical for achieving high thermal stability and maintaining the mechanical properties of SC after ageing in a harsh environment(150°C,with Cu,in air,7 days).Although higher amounts of space charges have been observed in SC/PP/SC samples with higher AO concentrations,the impact on space charge behaviours is less after ageing,suggesting that ageing(or operating at high temperature)leads to microstructure evolution in SC and can potentially mitigate space accumulation in PP-based insulating materials.

关键词： microstructure thermal high

high-voltage and Fast-Charging Lithium Cobalt Oxide Cathodes: From key Challenges and Strategies to Future Perspectives

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Engineering 2024年第6期37卷 105-127页

作者： Gongrui Wang Zhihong Bi Anping Zhang Pratteek Das Hu Lin Zhong-Shuai Wu State key laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Dalian National laboratory for Clean Energy Chinese Academy of SciencesDalian 116023China

Lithium-ion batteries(LIBs)with the“double-high”characteristics of high energy density and high power density are in urgent demand for facilitating the development of advanced portable ***,the lithium ion(Li+)-storage performance of the most commercialized lithium cobalt oxide(LiCoO_(2),LCO)cathodes is still far from satisfactory in terms of high-voltage and fast-charging capabilities for reaching the double-high ***,we systematically summarize and discuss high-voltage and fast-charging LCO cathodes,covering in depth the key fundamental challenges,latest advancements in modification strategies,and future perspectives in this *** and elaborated discussions are first presented on key fundamental challenges related to structural degradation,interfacial instability,the inhomogeneity reactions,and sluggish interfacial *** provide an instructive summary of deep insights into promising modification strategies and underlying mechanisms,categorized into element doping(Li-site,cobalt-/oxygen-site,and multi-site doping)for improved Li+diffusivity and bulkstructure stability;surface coating(dielectrics,ionic/electronic conductors,and their combination)for surface stability and conductivity;nanosizing;combinations of these strategies;and other strategies(i.e.,optimization of the electrolyte,binder,tortuosity of electrodes,charging protocols,and prelithiation methods).Finally,forward-looking perspectives and promising directions are sketched out and insightfully elucidated,providing constructive suggestions and instructions for designing and realizing high-voltage and fast-charging LCO cathodes for next-generation double-high LIBs.

关键词： Lithium cobalt oxide high energy/power density Fast-charging high-voltage Lithium-ion battery

Study on surface discharge of nonlinear conductive epoxy resin/SrTiO3 composites in 80–300 K temperature zone

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high voltage 2024年第1期9卷 117-126页

作者： Yunqi Xing Bin Wang Mingyang Wang Jiakai Chi Peng Jia Rongjin Huang State key laboratory of Reliability and Intelligence of Electrical Equipment Hebei University of TechnologyTianjinChina key laboratory of Electormagnetic Field and Electrical Apparatus Reliability of Hebei Province Hebei University of TechnologyTianjinChina key laboratory of Special Machine and high voltage Apparatus(Ministry of Education) Shenyang University of TechnologyShenyangChina State Grid Tianjin high voltage Company TianjinChina China Energy Engineering Group Tianjin Electric Power Design Institute Co. Ltd.TianjinChina CAS key laboratory of Cryogenics Technical Institute of Physics and ChemistryBeijingChina

Bisphenol F epoxy resin(EP)is often used in terminal current lead insulation of superconducting equipment because of its good insulation performance,high mechanical strength,good toughness at cryogenic temperatures,and resistance to cold shock and heat ***,due to the wide temperature range of 80–300 K and the strong electric field,the EP-N_(2)interface is prone to surface flashover,resulting in terminal insulation *** improve the reliability of the current lead insulation,non-linear conductive EP/strontium titanate(SrTiO_(3))composites were prepared by modification with nano *** changes of dielectric,surface discharge,flashover,and trap distribution characteristics of composite materials were studied,and the mechanism of SrTiO_(3)on the surface flashover of composite materials was *** results show that the conductivity of the composite increases with the rise of SrTiO_(3)filling content,and the amplitude of improvement is greater under the strong electric field,showing a more significant *** composite has a lower trap energy level and a greater number of shallow traps compared to pure EP,which accelerates surface charge detrapping and reduces charge accumulation,effectively enhancing the discharge and surface flashover voltage of the composite.

关键词： composites composite insulation

Flow Field Simulation and Parameter Analysis of Hydraulic Unbalanced Bionic Self-recovery Actuator for Rotary Equipment

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Journal of Bionic Engineering 2024年第1期21卷 325-343页

作者： Wei Li Xin Pan Dehong Ge Jinji Gao key laboratory of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China beijing key laboratory of high-End Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China

The rotor is the most important component of rotating machinery,and the vibration produced by its mass unbalance has a serious influence on the secure and steady operation of the machine,so an effective online suppression technology is urgently needed.A new hydraulic unbalanced bionic self-recovery system is introduced,imitating the way of manually repairing faulty *** accomplish the effect of actuator mass redistribution,the technology employs pressurized air to drive the quantitative transfer of liquid in the reservoir cavity at opposite *** can complete the online adjustment of the equipment's balancing state and suppress the unbalanced vibration of equipment in real time,which gives the equipment the ability to maintain an autonomous health state and improve equipment *** composition and working principle of the system are introduced in detail,and the key performance parameters,such as the minimum running speed and the balancing liquid transfer speed,are analyzed *** fluid-solid coupling model of the actuator was established,and the two-phase flow from inside the hydraulic unbalanced bionic self-recovery actuator was simulated under multiple working conditions and the performance parameters were quantitatively analyzed.A balancing simulation test bed was built,and its effectiveness was verified by performance parameter tests and unbalanced bionic self-recovery *** experimental results show that the mass distribution adjustment of the balancing disk can be achieved using different viscosity balancing liquid,and the response of liquid viscosity 10 cSt is faster than that of liquid viscosity 100 cSt in the process of balancing liquid transfer,and the time is reduced by more than 75%;the system can reduce the simulated rotor amplitude from 18.3μm to 10.6μm online in real time,which provides technical support for the subsequent development of a new generation of bionic intelligent equipment.

关键词： Engineering self-recovery-Bionics Simulation analysis Self-recovery regulation

Prediction of Coefficient of Restitution for Impact Elastoplastic Spheres Considering Finite Plate Thickness

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Chinese Journal of Mechanical Engineering 2024年第4期37卷 183-193页

作者： Yunfeng Fan Hao Wang Tao Zhou Limin Zou Zhinong Jiang Minghui Hu State key laboratory of high-end Compressor and System Technology Beijing University of Chemical TechnologyBeijing 100029China China Ship Research and Development Academy Beijing 100101China key Lab of Engine Health Monitoring-Control and Networking of Ministry of Education Beijing University of Chemical TechnologyBeijing 100029China beijing key laboratory of high-End Mechanical Equipment Health Monitoring and Self-Recovery Beijing University of Chemical TechnologyBeijing 100029China

Collisions between objects are a relatively common phenomenon in *** of collision processes can greatly contribute to solving problems such as impact-rub faults and particle *** coefficient of restitution is a critical parameter in the analysis of collision *** experiments have shown that the coefficient of restitution is closely related to the plate thickness,and the smaller the plate thickness,the more inaccurate the coefficient of restitution predicted by the existing model,which seriously affects the process of collision *** remedy this shortcoming,this paper proposes a plate thickness influence factor with the ratio of sphere diameter to plate thickness as the *** plate thickness influence factor can optimize the coefficient of restitution model to effectively predict the coefficient of restitution of impacting elastoplastic spheres with finite plate ***,the validity of the new model is verified using a large amount of experimental data.

关键词： Collision Coefficient of restitution Energy loss Sphere