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High Voltage 2024年第1期9卷 46-55页

作者： Yan Yang Xueyang Bai Yuxing Lei Kai Liu Guangning Wu School of Electrical Engineering Southwest Jiaotong UniversityChengduChina

The lifetime model of turn-to-turn insulation in inverter-fed motors is studied.A lifetime model has been built by considering the effect of inverter-generated high voltage rise rate(dv/dt up to 20 V/ns).This model is followed by the generalised probabilistic model,in which the lifetime is proportional to the nth power of the voltage rise ***,by investigating the effect of voltage rise rate on the partial discharge characteristics,it is found that the effect of voltage rise rate on the charge transport process in a voltage cycle is similar to that of the voltage *** enhanced partial discharge activity and induced charges are responsible for accelerated ageing and thus determine the final lifetime of turn-to-turn *** this case,the generalised probabilistic electric lifetime model is applicable to the voltage rise rate as well as the voltage amplitude.

关键词： lifetime inverter insulation

Analysis of multi-objective optimisation method for main insulation structure configuration scheme of valve-side winding of ultra-high voltage converter transformer considering multi-field coupling

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High Voltage 2024年第2期9卷 296-308页

作者： Lijun Yang Zhidong Cheng Li Cheng Ruijin Liao State Key Laboratory of Power Transmission Equipment Technology School of Electrical EngineeringChongqing UniversityChongqingChina

Because DC conductivities of oil-paper materials can be easily affected by electric field and temperature,the electrical properties under electro-thermal coupling of oil-paper materials should be considered when optimising the insulation structure of valve-side winding of the converter *** on the finite element multi-physical field coupling simulation,the multi-objective optimisation of main insulation structure of valve-side winding is carried *** view of the high time consuming of multi-physical field calculation and the actual needs of an insulation structure optimisation,the Kriging method and technique for order preference by similarity to the ideal solution(TOPSIS)method are introduced,and combines them with NSGA-II to obtain a joint algorithm that can be used for the optimisation of insulation structure of the converter *** using the joint algorithm of multi-objective optimisation,the insulation structure configuration scheme of valve-side winding is *** can be seen from the experiment result that,on the one hand,the joint algorithm adopted can obtain the insulation structure configuration scheme that meets the design *** the other hand,when facing the configuration scheme optimisation under multi-field coupling,the computational time required by this method is only 0.15%of that required by original genetic algorithm.

关键词： converter insulation coupling

Nano-silica modified lightweight and high-toughness carbon fiber/phenolic ablator with excellent thermal insulation and ablation performance

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Defence Technology（防务技术） 2024年第1期31卷 192-199页

作者： Wenjie Xu Wenda Song Xianfeng Jia Cheng Ma Jitong Wang Wenming Qiao Licheng Ling State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China School of Chemical Engineering and Materials Changzhou Institute of TechnologyChangzhou 213032China Key Laboratory of Specially Functional Polymeric Materials and Related Technology(Ministry of Education) School of Materials Science and EngineeringEast China University of Science and TechnologyShanghai 200237China

Lightweight and high-toughness carbon fiber/phenolic ablator(CFPA)is required as the Thermal Protection System(TPS)material of aerospace vehicles for next-generation space *** improve the ablative properties,silica sol with good particle size distribution prepared using tetramethoxysilane(TMOS)was blended with natural rubber latex and deposited onto carbon fiber felt,which was then integrated with phenolic aerogel matrix,introducing nano-silica into the framework of *** modified CFPA with a low density of 0.28—0.31 g/cm3exhibits strain-in-fracture as high as 31.2%and thermal conductivity as low as 0.054 W/(m·K).Furthermore,a trace amount of nano-silica could effectively protect CFPA from erosion of oxidizing atmosphere in different high-temperature *** oxyacetylene ablation test of 3000°C for 20 s shows a mass ablation rate of 0.0225 g/s,a linear ablation rate of 0.209 mm/s for the modified CFPA,which are 9.64%and 24.82%lower than the unmodified ***,the long-time butane ablation test of 1200°C for 200 s shows an insignificant recession with mass and linear ablation rate of 0.079 g/s and 0.039 mm/s,16.84%and 13.33%lower than the unmodified ***,the fixed thermocouple in the test also demonstrates a good thermal insulation performance with a low peak back-face temperature of 207.7°C,12.25%lower than the unmodified ***,the nano-silica modified CFPA with excellent overall performance presents promising prospects in high-temperature aerospace applications.

关键词： Nano-silica Carbonfiber Phenolic aerogel insulation Ablation

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Dynamics of an impurity ion transport in oil-paper insulation under various electric fields

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High Voltage 2024年第1期9卷 66-80页

作者： Yuanyang Ren Yang Wang Qiankai Zhang Jiayu Xiong Wen Cao Zepeng Lv Kai Wu State Key Laboratory of Electrical insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina School of Electronics and Information Xi'an Polytechnic UniversityXi'anChina State Grid Sichuan Electric Power Research Institute ChengduChina

The ionic transport process is an important counterpart to charge transport in oil-paper insulation,and it significantly impacts oil flow electrification at the oil-paper *** this,the dynamics of this phenomenon and the underlying mechanisms remain unclear,particularly at the molecular *** understand this fundamental aspect,we conduct Molecular Dynamics study on the transport behaviour of an impurity ion in different oil-paper insulation models under various external electric *** influence factors,such as external electric fields,temperatures,and local structural characteristics,are investigated in relation to the corresponding ionic mobility in different polymer *** to the simulations,ionic mobility and its response to electric fields are higher in weaker electrostatic *** a result,mineral oil exhibits the highest ionic mobility and the most substantial enhancement of ionic mobility by external electric fields,followed by vegetable oil,oil-paper blends,and insulating *** significant deviation in ionic mobility between oil and paper leads to the formation of an electric double layer near the oil-paper *** underlying physical mechanisms of different ionic mobility and its response to the electric field in different polymer models could be explained by the different polymer structural influences in terms of interaction energy and coordination numbers in a static manner,as well as by the interactions between the impurity ion and its surrounding atoms in terms of lifetime correlation functions and velocity autocorrelation functions in a dynamic *** addition,the influence of temperature on ionic mobility in mineral and vegetable oil is examined,and their activation energies are *** in the fundamental understanding of the dynamics of the ion transport process in oil-paper insulation is vital to improving their insulating properties for oil-impregnated power transformers.

关键词： insulation transport fields

Preparation of Polyurea Elastomer with Flame Retardant, insulation and Thermal Conductivity Properties

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Journal of Wuhan University of Technology(Materials Science) 2024年第3期39卷 781-789页

作者：方今 DONG Yang LU Shangkai LIU Junbang AI Lianghui 刘平 State Key Laboratory of Luminescent Materials and Devices Research Institute of Materials ScienceSouth China University of TechnologyGuangzhou 510640China

By using 6,6-((sulfonylbis(4,1-phenylene)bis(azanediyl))bis(thiophen-2-ylm-ethylene))bis6H-di-benzo[c,e][1,2]oxaphosphinine 6-oxide(DOPO-N)as phosphorus-nitrogen flame retardant,the polyurea(PUA)with flame retardant properties(PUA/DOPO-N)was *** addition,organically modified montmorillonite(OMMT)and magnesium hydroxide(MH)were used as co-effectors respectively,and the flame retardant PUA(PUA/DOPO-N/OMMT and PUA/DOPO-N/MH)were also *** properties,flame retardant properties,flame retardant mechanism and mechanical properties of PUA/DOPO-N,PUA/DOPO-N/OMMT and PUA/DOPO-N/MH were investigated by thermogravimetric(TG)analysis,limiting oxygen index(LOI),UL 94,cone calorimeter test,scanning electron microscopy(SEM),and tensile *** results show that the LOI value of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are 27.1%,27.7%,and 28.3%,respectively,and UL 94 V-0 rating is *** with PUA,the peak heat release rate(pk-HRR),total heat release(THR)and average effective heat combustion(av-EHC)of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH decrease *** results indicate that the residual chars of PUA/20%DOPO-N,PUA/18%DOPO-N/2%OMMT and PUA/15%DOPO-N/5%MH are completer and more *** complex of DOPO-N/OMMT and DOPO-N/MH have synergistic flame *** mechanical properties of PUA can be improved by the addition of DOPO-N,DOPO-N/OMMT and DOPO-N/MH,*** insulation performance test shows that the volume resistivity of PUA/20%DOPO-N is 6.25×10^(16)Ω.***,by using modified boron nitride(MBN)as heat dissipating material,the complex of PUA/MBN was prepared,and the thermal conductivity of PUA/MBN was *** thermal conductivity of PUA/8%MBN complex coating at room temperature is 0.166 W/(M·K),which is a 163%improvement over pure PUA.

关键词： polyurea organic flame retardant inorganic flame retardant synergistic flame retardancy insulation thermal conductivity

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A novel approach towards parametric assessment of reliability and resilience of high voltage mica-based insulation systems by statistical analysis of experimental failure data

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High Voltage 2024年第2期9卷 495-507页

作者： Shahram Negari Davoud Esmaeil Moghadam Integrated Power Services ClevelandOhioUSA Valeo eAutomotive Germany GmbH ErlangenGermany

insulation systems in high-voltage electric machines play a pivotal role in the reliable operation and longevity of the ***-based insulation materials have proven to possess and maintain excellent dielectric properties in the long run and prevent premature insulation *** qualifications tests,such as voltage endurance,are outlined in IEC and IEEE *** authors,however,take a different parametric approach,opting for reliability assessment of insulation systems using derived three-parameter Weibull ***,instead of simple pass–fail criteria,empirical data is employed to determine failure rate probabilities quantitatively and *** data,including breakdown,dissipation factor,and partial discharge mea-surements,are used to construct the Weibull distribution model to predict fault and failure rates and calculate hazard *** rigorous examinations interpreted through the analytical model help assess insulation system resilience and particularly the impact of electrical field stress and mica *** of electrical stress from 66.75 to 71.20 V/mil demonstrated how the mean time to failure of the system changed from 146.4 to 85.1 at 3 Un,hence identifying opportunities for design improvement and uncovering performance ***,the developed framework enhances comprehension of insulation system failure probabilities,guiding design decisions and ensuring a secure and reliable operation of electrical machines across applications.

关键词： insulation parametric approach

Photon counting technique as a potential tool in micro-defect detection of epoxy insulation pull rod in gas-insulated switchgears

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High Voltage 2024年第2期9卷 267-274页

作者： Xianhao Fan Shu Niu Hanhua Luo Jizhong Liang Fang Liu Wenqiang Li Weidong Liu Wensheng Gao Yulong Huang Chuanyang Li Jinliang He School of Electrical Engineering Tsinghua UniversityBeijingChina Electric Power Research Institute Shangxi Power Grid CorporationTaiyuanShanxiChina Shandong Taikai Electrical insulation Co. Ltd.TaianShandongChina

The micro-defects in epoxy-based insulation materials generate a local high electric field which results in continuous degradation,seriously endangering the insulation system of gas-insulated switchgears.A highly sensitive detection technique is reported for micro-defects of insulation pull rods based on the photon counting(PC)*** re-sults demonstrated that for an epoxy-based insulation pull rod,the photons released during electroluminescence and ionisation at 2 kV,which is less than the partial discharge inception voltage,can be clearly *** findings presented a strong correlation between photon counts and defect *** has been conducted to elucidate the mechanism behind defect-induced PC,employing the amplification of ionising luminescence through electric field distortion induced by micro defects and the augmentation of electroluminescence through the aggregation of trap *** this regard,the authors verified that PC can serve as a potential tool in the detection of micro-insulation defects,which also has huge potential in online insulation condition monitoring.

关键词： technique. insulation defect

Sound insulation measurement of building components combining diffuse acoustic field excitation and near-field acoustic holography reconstruction

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Chinese Journal of Acoustics 2024年第2期43卷 248-273页

作者： WANG Hongwei XIONG Wei WANG Qiaochu ZHANG Guangyao YANG Chenxi School of Architecture South China University of TechnologyGuangzhou 510640 State Key Laboratory of Subtropical Building Science South China University of TechnologyGuangzhou 510640

A method for measuring the airborne sound insulation of building components combining diffuse acoustic field(DAF) excitation and near-field acoustic holography(NAH)radiation intensity reconstruction is proposed. In this method, the DAF is first used to excite the vibration of the component and obtain the incident sound power, then the normal sound intensity distribution with high spatial resolution on the surface of the component is reconstructed from the radiation sound pressure field using the NAH, and finally, according to the sound intensity distribution, the radiated sound power is calculated and the radiation heat areas are located, so as to realize the measurement of sound insulation and sound insulation defects of components. The experimental research in a sound insulation room shows that under the condition that the test distance and sampling interval are both0.04 m, the error of the sound insulation measured by this method compared to the sound pressure method is less than 3.3 d B in the 100–5000 Hz frequency band and less than1.3 d B in the 250–3150 Hz frequency band, and the positioning accuracy of round holes(diameter: 8 mm) and rectangular slots(length: 80 mm, width: 3 mm) is up to the centimeter level. At the same time, the method has strong stability under the influence of certain amount of reverberation and background noise. When reverberation time in the receiving room increases from 1.0 s to 3.4 s(step size: 0.6 s), and the signal-to-noise ratio decreases from 10 d B to 0 d B(step size: 5 d B), the sound volume measurement errors are within 0.8 d B and 0.3 d B, and the defect location errors are within 0.037 m and 0.035 *** proposed method helps to improve the measurement capability of sound insulation characteristics of building components in the laboratory, and it is robust to the receiving room test environment.

关键词： insulation excitation field

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Polar bear-inspired thermal material:The next generation of ultra-thin insulation

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China Textile 2024年第1期 16-17页

Chinese scientists have published a paper in the journal Science,describing their invention of a fibre-woven garment that imitates polar bear *** garment is as warm as a down jacket,despite being only one-fifth as *** scientists used polar bear fur as a starting point in their search for a solution to address the weaknesses and processing challenges of traditional *** advancement in aerogel technology,particularly for textiles,overcomes the limitations of conventional *** maintains its heat-absorbing properties even after being stretched,washed,and dyed.

关键词： insulation journal fibre

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Correction to Impact of air pressure variations on electrical vehicle motor insulation

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High Voltage 2024年第2期9卷 508-508页

Wang,P.,et al.:Impact of air pressure variations on electrical vehicle motor *** Voltage.8(5),1011-1019(2023).https://***/10.1049/hve2.12346 The authors wish to bring to the readers'attention the following error in the article by Peng Wang,Chaofan Yu,Shakeel Akram,Ziyuan Fan,Wenhuan Zhao,‘Impact of air pressure variations on electrical vehicle motor insulation’.

关键词： Impact insulation air