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High Voltage 2024年第5期9卷 1011-1020页

作者： Yingfan Zhang Haohuan Wang Zhengyong Huang Jian Li state key laboratory of power transmission equipment technology Chongqing UniversityChongqingChina

Surface flashover is a crucial issue for the miniaturisation of electronic facilities in military,industrial,and aerospace *** oriented hexagonal boron nitride(hBN)composites,due to excellent thermal and electrical insulating properties,show a potential application in high-voltage power equipment,while the surface flashover performance of hBN composites dependent on oriented hBN texture is rarely *** effects of hBN orientation and contents on the surface flashover performances of oriented hBN composites are *** isothermal surface potential decay of the oriented hBN composites was also *** is found that the charge transportation could be adjusted by the hBN orientation,thus regulating surface flashover *** DC flashover voltage of the in-plane oriented hBN composites with a thickness of 15μm reached the maximum of 27.6 kV at the hBN loading of 20 wt%,14.5%higher than that of the pure *** carrier mobility of out-of-plane oriented hBN composites is about three times greater than that of the in-plane oriented composites,indicating that the charges are easily transported along the hBN basal *** larger carrier mobility causes charge dissipation in composites near the electrode at the hBN basal plane parallel to the axis of electrodes and inhibits the distortion of the surface electric field on the composites,thus enhancing the surface ***,developing oriented insulators for highvoltage applications and enabling an optimum insulation design would be beneficial because of the compactness and high reliability of power apparatus for use in power grids.

关键词： composites surface boron

Local electron mean energy profile of positive primary streamer discharge with pin-plate electrodes in oxygen nitrogen mixtures

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Chinese Physics B 2013年第1期22卷 394-402页

作者：司马文霞彭庆军杨庆袁涛施健 state key laboratory of power transmission equipment & System Security and New technology Chongqing University

Local electron mean energy （LEME） has a direct effect on the rates of collisional ionization of molecules and atoms by electrons. Electron-impact ionization plays an important role and is the main process for the production of charged particles in a primary streamer discharge. Detailed research on the LEME profile in a primary streamer discharge is extremely important for a comprehensive understanding of the local physical mechanism of a streamer. In this study, the LEME profile of the primary streamer discharge in oxygen-nitrogen mixtures with a pin-plate gap of 0.5 cm under an impulse voltage is investigated using a fluid model. The fluid model includes the electron mean energy density equation, as well as continuity equations for electrons and ions and Poisson＇s electric field equation. The study finds that, except in the initial stage of the primary streamer, the LEME in the primary streamer tip tends to increase as the oxygen-nitrogen mole ratio increases and the pressure decreases. When the primary streamer bridges the gap, the LEME in the primary streamer channel is smaller than the first ionization energies of oxygen and nitrogen. The LEME in the primary streamer channel then decreases as the oxygen-nitrogen mole ratio increases and the pressure increases. The LEME in the primary streamer tip is primarily dependent on the reduced electric field with mole ratios of oxygen-nitrogen given in the oxygen-nitrogen mixtures.

关键词： local electron mean energy profile primary streamer discharge electric field distribution gas discharge

3D Printing of Tough Hydrogel Scaffolds with Functional Surface Structures for Tissue Regeneration

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Nano-Micro Letters 2025年第2期17卷 18-45页

作者： Ke Yao Gaoying Hong Ximin Yuan Weicheng Kong Pengcheng Xia Yuanrong Li Yuewei Chen Nian Liu Jing He Jue Shi Zihe Hu Yanyan Zhou Zhijian Xie Yong He state key laboratory of Fluid power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China Liangzhu laboratory Zhejiang UniversityHangzhou 310027People’s Republic of China key laboratory of 3D Printing Process and equipment of Zhejiang Province College of Mechanical EngineeringZhejiang UniversityHangzhou 310027People’s Republic of China Stomatology Hospital School of StomatologyZhejiang University School of MedicineHangzhou 310027People’s Republic of China state key laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001People’s Republic of China Institute of Digital Medicine Nanjing First HospitalNanjing Medical UniversityNanjing 210006People’s Republic of China

Hydrogel scaffolds have numerous potential applications in the tissue engineering ***,tough hydrogel scaffolds implanted in vivo are seldom reported because it is difficult to balance biocompatibility and high mechanical *** by Chinese ramen,we propose a universal fabricating method(printing-P,training-T,cross-linking-C,PTC&PCT)for tough hydrogel scaffolds to fill this ***,3D printing fabricates a hydrogel scaffold with desired structures(P).Then,the scaffold could have extraordinarily high mechanical properties and functional surface structure by cycle mechanical training with salting-out assistance(T).Finally,the training results are fixed by photo-cross-linking processing(C).The tough gelatin hydrogel scaffolds exhibit excellent tensile strength of 6.66 MPa(622-fold untreated)and have excellent ***,this scaffold possesses functional surface structures from nanometer to micron to millimeter,which can efficiently induce directional cell ***,this strategy can produce bionic human tissue with mechanical properties of 10 kPa-10 MPa by changing the type of salt,and many hydrogels,such as gelatin and silk,could be improved with PTC or PCT *** experiments show that this scaffold can effectively promote the new generation of muscle fibers,blood vessels,and nerves within 4 weeks,prompting the rapid regeneration of large-volume muscle loss injuries.

关键词： 3D printing Tough hydrogel scaffold Functional surface structure Tissue regeneration Biomaterials

Fast electrothermal coupling calculation method for supporting digital twin construction of electrical equipment

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High Voltage 2023年第2期8卷 390-400页

作者： Xiaosong Zhu Youyuan Wang Ruixiao Meng Shi Long Shaowen Wu state key laboratory of power transmission equipment and System Security and New technology(Chongqing University) ChongqingChina

The failure of electrical equipment directly or indirectly caused by overheating has become one of the main reasons for equipment *** real-time condition monitoring method of electrical equipment based on digital twin(DT)has received extensive attention and is considered as a technology with great engineering values and excellent application ***,the current calculation of DT mostly relies on the traditional finite element method(CFEM).This method becomes less computationally efficient as the size of the DT increases,especially for electrical equipment with high *** is difficult to meet the requirements real-time calculation in ***,starting from the algorithm optimization and parallel architecture,based on the weighted residual method and stabilised conforming nodal integration,a novel discrete method of electrothermal coupling equation is proposed and the data storage structure of the algorithm from the bottom layer is redesigned,and the corresponding GPU and multi-core CPU parallel framework are ***,taking the high voltage bushing as an example,the correctness of the method in this paper is verified by the CFEM code and commercial software *** the same grid and accuracy requirement,the calculation time is shortened by at least five times than *** the method is easy to extend to other types of multi-physics calculations.

关键词： electrical coupling method

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

Microstructure-ionisation potential relationship analysis for understanding the molecular ionisation difference of natural esters during the impulse discharge via DFT calculation

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High Voltage 2024年第4期9卷 920-929页

作者： Jingwen Zhang Jian Hao Wenyu Ye Junyi Zhang Ruijin Liao state key laboratory of power transmission equipment technology School of Electrical/EngineeringChongqing UniversityChongqingChina

Understanding the impulse discharge behaviour of natural ester(NE)is crucial for its safe application in high-voltage *** ionisation potential(IP)of triglycerides plays a significant role in the process of molecular ionisation during impulse discharge for *** correlation coefficients between molecular size,frontier orbital,electrostatic potential,polarity,and IP were *** the quantitative microstructure-IP model for triglycerides were built,which revealed that IP is strongly related to the highest occupied molecular orbital(HOMO)energy EHM,as well as the average value of positive electrostatic potential V_(p)(t),the average value of negative electrostatic potential V_(p)(-),and the surface area of negative electrostatic potential S(-).The HOMO and negative electrostatic potentials of saturated triglycerides are predominantly linked to the carbonyl O ***,in unsaturated triglycerides,the influence of C=C double bonds on HOMO and negative electrostatic potentials is more ***,the IP of unsaturated NE with C=C bonds is lower than that of saturated NE,rendering it more susceptible to ionisation under a strong electric field which is unfavourable for impulse breakdown *** structure-property correlation analysis is valuable for understanding ionisation mechanism during the impulse discharge breakdown of NE at the microscopic level.

关键词： electrostatic potential bonds

Multiple Failure Modes of Compressor Station Incorporated into Risk Evaluation of Electricity-gas Integrated Energy Systems

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CSEE Journal of power and Energy Systems 2023年第4期9卷 1439-1448页

作者： Yi Tang Yuan Zhao Wenyuan Li Kaigui Xie Juan Yu the state key laboratory of power transmission equipment and System Security and New technology Chongqing UniversityChongqing 400044 China

Multiple failure modes of gas compressor stations have not been modeled into risk evaluation of electricity-gas integrated energy system(EGIES).This paper presents a method to incorporate multiple failure modes of compressor stations with bypass systems in the EGIES risk *** outage models representing multi-states and multi-failure-modes of com-pressor stations and a bi-level Monte Carlo sampling algorithm for the models are developed.A novel network model of EGIES considering compressor stations with multiple failure modes is *** EGIES with a modified RBTS and an 11-node gas system is used to demonstrate the effectiveness of the proposed method and *** indicate that compressor stations have both positive and negative significant impacts on the risk of *** systems for compressor stations can effectively offset the negative *** compressor stations and their station failures in the risk evaluation of EGIES may result in an inaccurate estimation of the system risk levels and even lead to a misleading conclusion in system *** Terms-Compressor station,electricity-gas integrated energy system,multiple failure modes,risk evaluation.

关键词： Compressor station electricity-gas integrated energy system multiple failure modes risk evaluation.

Harmonic Damping Characteristics of Single-phase Full-bridge Rectifier Based Loads

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CSEE Journal of power and Energy Systems 2022年第5期8卷 1448-1456页

作者： Yihang Zhang Jiaming Lu Jing Yong state key laboratory of power transmission equipment&System Security and New technology Chongqing UniversityChongqingChina

With the rapid development of power electronic technology,many linear single-phase loads in low voltage systems are replaced by those equipped with a single-phase diode ***,most of single-phase loads become harmonic producers due to their nonlinear *** nonlinear loads may have different damping characteristics at harmonic frequencies,which could cause potential power quality *** paper studies the harmonic damping characteristics of such nonlinear *** harmonic damping index is defined to quantify the damping effect of nonlinear loads of harmonic frequencies by analyzing the harmonic ***,the harmonic damping index of different harmonic frequencies is compared through simulations and *** results show that the nonlinear load has a constant damping effect for the fundamental frequency,but a stronger damping for the harmonic *** harmonic damping of such nonlinear loads varies with the harmonic phase angle of supply voltage,and becomes stronger with the increase of the harmonic *** implies that this type of nonlinear load may be beneficial to the suppression of harmonic resonance.

关键词： Damping effect harmonic domain model harmonic impedance nonlinear load

Per-unit Scheme for Integrated Solution of Hybrid power-water Flow Problem

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Journal of Modern power Systems and Clean Energy 2023年第2期11卷 680-685页

作者： Xia Zhao Hong Tan Luo Wang Mingyi Sun state key laboratory of power transmission equipment&System Security and New technology Chongqing UniversityChongqingChina

When applying the widely-used Newton-Raphson(N-R)method to the integrated solution of the hybrid power-water flow problem of the power-water integrated energy system(PW-IES),it is found that there are numerical differences among Jacobian elements,which may yield an ill-conditioned Jacobian matrix and even cause convergence ***,this letter proposes to per-unitize the water distribution network(WDN)to reduce the numerical differences and thus to improve the Jacobian matrix conditioning and the integrated N-R solution to the hybrid power-water flow problem.

关键词： Integrated energy system load flow Newton-Raphson method water distribution network power-water flow

An Adaptive Fast Multipole Higher Order Boundary Element Method for power Frequency Electric Field of Substation

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Chinese Physics Letters 2010年第3期27卷 144-147页

作者：张占龙邓军肖冬萍何为唐炬 state key laboratory of power transmission equipment and System Security and New technology Chongqing University Chongqing 400030

An adaptive fast multipole higher order boundary element method combining fast multipole （FM） with a higher order boundary element method is studied to solve the power frequency electric field （PFEF） of substations. In this new technique, the iterative equation solver GMRES is used in the FM, where matrix-vector multiplications are calculated using fast multipole expansions. The coefficients in the preconditioner for GMRES are stored and are used repeatedly in the direct evaluations of the near-field contributions. Then a 500kV outdoor substation is modeled and the PFEF of the substation is analyzed by the novel algorithm and other conventional methods. The results show that, in computational cost and the storages capability aspects, the algorithm proposed in this study has obvious advantages. It is suitable for the calculation of the large-scale PFEF in complex substations and the design of electromagnetic compatibility.

关键词： Computational physics Accelerators beams and electromagnetism Instrumentation and measurement