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Condition monitoring and diagnosis of power equipment:review and prospective

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High Voltage 2017年第2期2卷 82-91页

作者： shengtao li Jianying li State Key Laboratory of Electrical Insulation and Power equipment Xi'an Jiaotong UniversityXi'an710049People's Republic of China

To ensure the power system operates safely and reliably,it is essential to monitor and evaluate the health condition of power equipment on-line or *** study reviews the research status in condition monitoring and diagnosis of power equipment,including transformer,gas insulated switchgear,cable,external insulation,generator,and power capacitor in recent *** much progress has been made in technologies of condition monitoring and fault diagnosis such as test accuracy,fast and accurate fault localisation and recognition of fault types,there are still many deficiencies which needs further research work,including the reliability of signal collection from sensors,the accuracy of data treatment and analysis,anti-interference performance of test equipment,appropriate models used for condition *** prospective of condition monitoring and diagnosis technologies of power equipment are also presented in this *** is proposed that the application of big data,internet of things and cloud computing should be expected and given special attention in the near future.

关键词： diagnosis power fault

Development of epoxy resin with superior breakdown strength:A Review

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iEnergy

iEnergy 2024年第2期3卷 82-94,I0001页

作者： li shengtao li Mingru State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityShaanxi 710049China

Epoxy resin(EP)has been widely utilized in electrical equipment and electronic devices due to its fascinating electric,thermal,and mechanical ***,the complex insulation structures of modern power devices in high-voltage direct current systems pose several challenges for EP-based *** most significant among these challenges is the need for EP to stably operate under greater electric fields,requiring superior breakdown *** paper summarizes the key factors influencing the breakdown strength of EP and reviews reported methods for enhancing this *** the limitations of existing approaches,we propose that the emerging technology of molecule design offers a potentially optimal solution for developing EP with enhanced breakdown ***,we anticipate the future development direction of EP with satisfactory insulation *** believe that enhancing the breakdown theory of solid dielectrics,exploring new research and development methodologies,and creating environmentally friendly EP with high performance are primary focus *** hope that this paper will offer guidance and support for the future development of EP with superior breakdown strength,proving valuable in advancing EP-based dielectrics.

关键词： Epoxy resin breakdown strength electrical insulation

Understanding insulation failure of nanodielectrics:tailoring carrier energy

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High Voltage 2020年第6期5卷 643-649页

作者： shengtao li Dongri Xie Qingquan Lei State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anPeople's Republic of China College of Materials Science and Engineering Qingdao University of Science and TechnologyQingdaoPeople's Republic of China School of Electrical and Electronic Engineering Harbin University of Science and TechnologyHarbinPeople's Republic of China

Owing to the formation of interface and new feature of which, the properties of nanodielectrics can be improved. ‘Hard/soft interface’ and its trap distribution can be tailored by functionalised groups. Molecular simulation results show that the interaction energy and electrostatic potential are larger for the soft interface, which indicates the greater bonding strength with the polymer matrix and electrostatic force on charge carriers. Charge transport simulation indicates that the accumulation of homo-charges would form a reverse electric field and distort electric field distribution. The injection depth would be restricted at the vicinity of sample/electrodes due to the greater trapping effect of deep traps, thus weakening the distortion in the sample bulk, thereby decreasing carrier energy and delaying the formation of impact ionisation. Based on the accumulation of carrier energy Φ = Eeλ, the idea of suppressing electron free path and carrier energy to enhance the insulation breakdown is confirmed. The classified effects of nanofillers during dc breakdown and corona-resistant are further understood from carrier energy. The introduced interfacial trap is effective in trapping carriers due to the low carrier energy under dc voltage, while ineffective in blocking the energetic charges during corona-discharge, but nanoparticles exert blocking and scattering effect against the energetic charges.

关键词： energy trapping interface

Optimal control for a class of impulsive switched systems

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Journal of Control and Decision 2023年第4期10卷 529-537页

作者： Xiaomei liu shengtao li Business School Shandong Normal UniversityJinanPeople’s Republic of China School of Information Science and Engineering Shandong Normal UniversityJinanPeople’s Republic of China

In this paper,an optimal switch-time control problem is solved for a class of impulsive switched autonomous *** considered systems jump at the switching times,and the sequence of active subsystems is *** control variables consist of the impulse times and a set of scalars which determine the jump ***,the subsystems do not require a refractory period,which can bring more *** the calculus of variation,the partial derivatives of the cost with respect to the control variables are derived,based on which the optimality conditions are ***,the obtained formulas can be used in some gradient descent algorithms to locate the optimal control ***,the viability of the proposed method is illustrated through two numerical examples.

关键词： Optimal control impulsive switched systems calculus of variation

Intelligent model prediction of fluctuant increase of maximum electric field in XLPE insulation using long short-term memory network algorithm

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High Voltage 2023年第1期8卷 70-80页

作者： Weiwang Wang Jiaju Lv Yong Feng Xinyuan li shengtao li State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

The electric field distortion due to space charge accumulations plays a significant role in the ageing,degradation and breakdown in failure of HVDC power ***,limited experimental results of the electric field dominated by space charges are insufficient to diagnose the power *** paper proposes an improved long short-term memory network(LSTM)model for predicting the fluctuating maximum electric field(Emax)in cross-linked polyethylene(XLPE)cable *** various Emax data derived from the complex space charge behaviours were measured using the pulsed electroacoustic *** model uses regularisation and dropout feedback in the LSTM unit,reducing the phenomenon of over-fitting due to the limited *** enhances the prediction accuracy and ability of long time prediction by improving the prediction of Emax with the non-linear *** predicted Emax approaches 190 kV/mm under 150 kV/mm and 60°C after 2 *** predicted large variation in Emax under 120 kV/mm and 20°C after 4 h ranges from 130 to 160 kV/*** indicates high electric stress in the cable insulation during continuous *** proposed LSTM model is of great importance to guide the diagnosis of cable degradation in HVDC power cables.

关键词： network prediction insulation

Progress in and prospects for electrical insulating materials

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High Voltage 2016年第3期1卷 122-129页

作者： shengtao li Shihu Yu Yang Feng State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049People’s Republic of China

The performance of electrical equipment and devices is determined to a great extent by the properties of their insulating *** power systems and electrical devices,insulating materials have to work in extreme circumstances that can include high temperature differences,intense radiation,and strong electric *** conditions demand high-quality insulating materials with superior electrical,thermal,and mechanical properties as well as resilience to other environmental *** study focuses on advances in insulating materials since the early 20th century and reviews the many developments in their properties and applications,including electric breakdown strength,thermal conductivity,temperature resistance,corona resistance,and specific energy storage in *** research progress on other properties is also covered,such as non-linearity and radiation *** into the properties of insulating materials can greatly assist in understanding their interface effects and composite structures,which in turn is helpful for discovering methods to improve the performance of electrical *** directions for research are proposed to guide new investigations and support the development of even better insulating materials.

关键词： electrical composite insulating

Power loss transition of stable ZnO varistor ceramics: Role of oxygen adsorption on the stability of interface states at the grain boundary

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Journal of Advanced Ceramics 2023年第5期12卷 972-983页

作者： Zhuolin Cheng Rou li Yiwei Long Jianying li shengtao li Kangning Wu State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong UniversityXi’an 710049China Department of Thermal and Fluid Engineering University of TwenteEnschede 7500AEthe Netherlands

Highly stable ZnO varistor ceramics with steadily decreasing power loss have been put into applications in electrical and electronic systems for overvoltage protections, even with the absence of general understandings on their aging behaviors. In this paper, we investigated their aging nature via conducting comparative direct current (DC) aging experiments both in air and in nitrogen, during which variations of electrical properties and interface properties were measured and analyzed. Notably, continuously increasing power loss with severe electrical degradation was observed for the sample aged in nitrogen. The power loss transition was discovered to be closely related to the consumption of oxygen adsorption at the grain boundary (GB), which could, however, remain constant for the sample aged in air. The interface density of states (DOS) Ni, which is crucial for pinning the potential barrier, was proved to decrease in nitrogen, but keep stable in air. Therefore, it is concluded that the oxygen adsorption at the GB is significant for the stability of interface states, which further correlates to the long-term stability of modern stable ZnO varistor ceramics.

关键词： ZnO varistor ceramics aging power loss oxygen adsorption interface states

Surface flashover in 50 years:Theoretical models and competing mechanisms

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High Voltage 2023年第5期8卷 853-877页

作者： Zhen li Ji liu Yoshimichi Ohki George Chen He Gao shengtao li Key Laboratory of Engineering Dielectrics and Its Application Ministry of EducationHarbin University of Science and TechnologyHarbinChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina Research Institute for Materials Science and Technology Waseda UniversityShinjuku‐kuJapan School of Electronics and Computer Science University of SouthamptonSouthamptonUK

Surface flashover is a devastating electronic avalanche along the gas–solid interface when a high electric field is applied,which is a potential issue that threatens the safe operations of advanced power electronic,electrical,and spacecraft ***,the underlying physical mechanisms for surface flashover development are still under investigation owing to the complex charge transport processes through the gas phase,solid phase,and gas–solid *** this study,the history of surface flashover theory in the last 50 years is introduced,and several key questions are reviewed from the perspective of the competing mechanisms of charge transport:the role of each phase in a surface flashover,the origin of surface charging,and effects of traps in solid on surface ***,some suggestions involve charge transport processes in each phase,and their correlations are put forward,and a predictable‘charge transport competitive flashover model’is proposed by clarifying the competing mechanisms of charge transport processes through multiple *** study summarises the history and hot topics of physical mechanisms of surface flashover proposed based on classic and recent progress and offers promising routes for developing a more precise surface flashover theory and improving surface flashover performances.

关键词： flash transport charge

Effect of matrix resin components on properties of the semi-conductive shielding material for high-voltage cable

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High Voltage 2024年第2期9卷 419-428页

作者： Guochang li Tianyao liu Xiaolong Chen Yanhui Wei Chuncheng Hao shengtao li Institute of Advanced Electrical Materials Qingdao University of Science and TechnologyQingdaoChina State Key Laboratory of Electrical Insulation and Power Equipment Xi'an Jiaotong UniversityXi'anChina

The semi-conductive shielding layer is an important part of the high-voltage cable,playing a role in uniform electric field and reducing the air gap at the *** overall performance of the cable is affected by the semi-conductive shielding layer with different base resin *** matrix resins of ethylene-vinyl acetate(EVA),ethylene-ethyl acrylate(EEA)and ethylene-butyl acrylate(EBA)were used to prepare the semi-conductive shielding materials of CB/EVA,CB/EEA and CB/*** influences of different matrix resins on the chemical,electrical,thermal and mechanical properties of the shielding materials were *** results show that CB has the best dispersion in EBA resin and the worst dispersion in EEA *** temperature in-flection points of CB/EVA,CB/EEA and CB/EBA shielding materials are 90°C,100°C and 110°C,respectively,and the CB/EBA shielding material has the lowest resistivity and the weakest positive temperature coefficient effect at room *** thermal conductivity of all three matrix resins is smaller than that of the shielding material,the thermal conductivity of CB/EVA and CB/EBA shielding materials show a slow increase with temperature,and the CB/EEA shielding material is the least affected by the *** mechanical properties of the three matrix resins and the three shielding materials are EBA>EVA>EEA,among them the stress of CB/EBA shielding material is 31.0 MPa and the strain is 570%.This work has important reference significance for the selection of shielding layer matrix resin and material formulation in engineering applications.

关键词： temperature. resin resins