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High Voltage 2023年第2期8卷 380-389页

作者： Xiao Yang Yi Zhang Zhuodong Yang Hao Dong Chengrong Li Bo Qi Licheng Lu caixin sun State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power UniversityBeijingChina Global Energy Interconnection Research Institute Co Ltd BeijingChina China Huaneng Group Co Ltd BeijingChina

The insulation performance of SF_(6)insulated high voltage direct current apparatus are often analysed in a pure electric field or electro-thermal coupled field while the fluid behaviour of SF_(6)gas flow is often ignored.However,frequent flashover along the support insulators inside the SF_(6)insulated wall bushing indicates that the fluid characteristics of SF_(6)may have considerable influence on the interior insulation performance of the bushing.This paper has simulated the thermo-fluid coupled field in the SF_(6)insulated wall bushing based on the finite element method model.The result shows that buoyant flow of SF_(6)has evident influence on the temperature distribution in the bushing.On this basis,the effect of the thermo-fluid field on the electric field distribution along the insulator as well as on the motion behaviour of the metallic particles is analysed.Furthermore,the effect of different thermal boundary conditions on analysis of the multiphysics field in the bushing is discussed and the most suitable one for simulation and experiment is suggested.Comparisons are made between different supporting structures and modification advices are proposed.This paper can serve as a good reference for subsequent research studies on SF_(6)insulated apparatus in which the temperature gradient or the motion of the micro-sized metallic particles shall be considered.

关键词： distribution thermal field

Finite Element Modeling of Unbounded Grounding System Considering Soil Ionization Characteristic

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高电压技术 2012年第8期38卷 2104-2111页

作者： CHEN Lin LI Jingli YANG Qing SIMA Wenxia sun caixin State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400030China

The aim of this paper is to calculate accurately the grounding performance of an unbounded grounding system under high-magnitude fault current.In this work,a finite element model is presented to compute the characteristic parameters of the grounding system in frequency domain.The ionization phenomenon in the soil surrounding the grounding electrode is taken into account by setting the resistivity of every soil element while the resistivity of each element is varying with the electric field intensity;not a priori hypothesis on the geometrical shape of the ionized region around the electrodes has to be enforced.Open boundaries of the grounding system are represented by introducing a spatial transformation formulation,which translates the semi-infinite space into the finite space without shortening the domain as in the traditional approach.The suggested modeling is validated by comparison of the calculated results,which are laid out for grounding rod and grounding grid,with experimental and simulation results found in literature.

关键词：局部放电射频信号放电量高电压技术

Influence of Vegetable Oil on the Thermal Aging Rate of Kraft Paper and its Mechanism

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高电压技术 2012年第8期38卷 2059-2067页

作者： YANG Lijun DENG Bangfei LIAO Ruijin sun caixin ZHU Mengzhao the State Key Laboratory of Transmission&Distribution Equipments and Power System Safety and New Technology Chongqing University Chongqing 400030 China~ Chongqing Electric Power Test&Research Chongqing 400015 China

With the development of new insulation materials,vegetable oil-the best substitute for mineral oil-has gradually been widely used in the liquid insulation of transformers.To investigate the influence of vegetable oil on the thermal aging rate of oil paper,Kraft paper impregnated with mineral oil and vegetable oil have been underwent thermally accelerated aging at three different temperatures.The degree of polymerization(DP) of Kraft paper was measured to indicate the aging degree of insulation paper.The aging rate of Kraft paper in mineral oil and vegetable oil was compared quantitatively,and results showed that vegetable oil retarded paper’s degradation rate and extended its useful lifetime.The reasons contributing to such phenomena were analyzed using X-ray Photoelectron Spectroscopy(XPS) and molecular simulation software.Kraft paper in vegetable oil had larger activation energy.Due to the larger interaction force between water and natural ester molecules,water molecules were easily bonded with natural ester,weakening the hydrolysis process of cellulose.Cellulose was chemically modified by natural ester during the thermal aging process,and the reactive-OH(hydroxyl) groups on the cellulose became esterified with fatty acid esters.Water molecules were firmly bounded to the ester groups on glucose produced by esterification.The long-chain fatty acid esterified to cellulose was parallel with cellulose chains and acted as a "water barrier" to further weaken the hydrolysis process.

关键词：局部放电射频信号放电量高电压技术

Inhibiting Ice Accumulation on Conductors by Using Sheath Treated with Super-hydrophobic Surfaces

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高电压技术 2013年第10期39卷 2500-2505页

作者： LI Jian GONG Yiyu LI Yong HU Jianlin sun caixin XIAO Daibo State Key Laboratory of Power Equipment & System Security and New Technology Chongqing University Chongqing 400030 China Chongqing Electric Power Research Institute State Grid Chongqing Electric Power Company Chongqing 401123 China Suizhou Electric Power Supply Company Suizhou 441300 China

Ice accumulation on transmission lines often leads to great damage to power systems.Super-hydrophobic surfaces are proposed to inhibit ice accumulation on electrical power equipment.A novel anti-icing method was presented for conductors with super-hydrophobic sleeves.The super-hydrophobic sleeves were prepared by applying polydimethylsiloxane(PDMS) and nano-silica hybrid coating on the outer surface of polyethylen terephthalate(PET) sleeves.Hydrophobicity and ice adhesion strength of the super-hydrophobic surface were investigated.Ice accumulation experiments were carried out on ordinary conductors,super-hydrophobic coated conductors,PET sleeve-covered conductors,and super-hydrophobic PET sleeve-covered conductors.Ice accumulation morphology,accumulated ice weight,and the icicle length of these four types of conductors were studied and analyzed.At the end of the 3 h ice accumulation experiment,the ice weight and icicle length on the conductor with super-hydrophobic PET sleeve was only approximately one tenth and one seventh of that on the untreated conductor respectively.Furthermore,the water contact angles of super-hydrophobic coated aluminum surface and super-hydrophobic coated PET sleeve were about 163o in average.The results indicate that the super-hydrophobic coating is effective in inhibiting ice accumulation on conductors.However,the use of a super-hydrophobic PET sleeve is a significantly more effective method,comparing with the application of a super-hydrophobic coating directly on the conductor.

关键词：疏水表面积冰超疏水性表面导线涂层导体聚二甲基硅氧烷治疗护套

Comparative Studyon DC Flashover Characteristics of Iced Insulators with Various Test Methods

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高电压技术 2012年第8期38卷 2051-2058页

作者： HU Jianlin LUO Mingwu JIANG Xingliang sun caixin ZHANG Zhijin SHU Lichun State Key Laboratory of Power Transmission Equipment ~ System Security and New Technology College of Electrical Engineering Chongqing University Chongqing 400030 China Hubei Suizhou Electric Power Supply Company Suizhou 441300 China

In this paper,the DC flashover characteristics of iced insulator strings were explored in the multi-functional artificial climate chamber by four methods,namely,the average flashover voltage method,the minimum flashover voltage method(U-curve method),the maximum withstand method and the 50% withstand method.Typical DC porcelain insulator strings and composite insulators were used as specimens.The results indicate that the average flashover voltage and the minimum flashover voltage obtained by the average flashover voltage method and the minimum flashover voltage method,respectively,obey a normal distribution.The 50% flashover voltage could be gained by the two methods with a minimal test number of nine and were about 8.0%~9.8% and 3.8%~5.9% respectively higher than that gained by the 50% withstand method.This justified the feasibility of employing the Ucurve method and the average flashover voltage method to study the flashover characteristics of iced insulators and their affecting factors.

关键词：局部放电射频信号放电量高电压技术

Chemical oscillation in electrochemical oxidation of methanol on Pt surface

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Science China Chemistry 2008年第4期51卷 322-332页

作者： LI LanLan WEI ZiDong QI XueQiang sun caixin YIN GuangZhi State Key Laboratory of Safety and New Technology for Electric Transmission&Distribution Chongqing UniversityChongqing 400044China School of Chemical Engineering Chongqing UniversityChongqing 400044China School of Material Science and Engineering Chongqing UniversityChongqing 400044China Key Laboratory of Exploitation of Southwestern Resources&the Environmental Disaster Control Engineering Chongqing Univer-sityChongqing 400044China

Based on dual path reaction mechanism, a nonlinear dynamics model reflecting the potential oscilla- tion in electrooxidation of methanol on Pt surface was established. The model involves three variables, the electrode potential (e), the surface coverage of carbon monoxide (x), and adsorbed water (y). The chemical reactions and electrode potential were coupled together through the rate constant ki = exp(ai(e ? ei)). The analysis to the established model discloses the following: there are different kinetics be- haviors in different ranges of current densities. The chemical oscillation in methanol electrooxidation is assigned to two aspects, one from poison mediate CO of methanol electrooxidation, which is the in- duced factor of the chemical oscillation, and the other from the oxygen-containing species, such as H2Oa. The formation and disappearance of H2Oa deeply depend on the electrode potential, and directly cause the chemical oscillation. The established model makes clear that the potential oscillation in methanol electrooxidation is the result of the feedback of electrode potential e on the reactions in- volving poison mediates CO and oxygen-containing species H2Oa. The numerical analysis of the estab- lished model successfully explains why the potential oscillation in methanol galvanostatic oxidation on a Pt electrode only happens in a certain range of current densities but not at any current density.

关键词： methanol electrooxidation electrochemical kinetics dual path reaction mechanism electrochemical oscillation bifurcation

DFT study of difference caused by catalyst supports in Pt and Pd catalysis of oxygen reduction reaction

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Science China Chemistry 2009年第5期52卷 571-578页

作者： LI Li WEI ZiDong ZHANG Yi QI XueQiang XIA MeiRong ZHANG Jie SHAO ZhiGang sun caixin State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400044China School of Material Science and Engineering Chongqing UniversityChongqing 400044China School of Chemistry and Chemical Engineering China West Normal UniversityNanchong 637002China School of Chemistry and Chemical Engineering Chongqing UniversityChongqing 400044China Dalian Institute of Chemical Physics Chinese Academy of SciencesDalian 116023China

Based on an experimental phenomenon that catalytic activity of Pt and Pd for oxygen reduction reaction (ORR) changes with catalyst supports from C to TiO2, density function theory (DFT) was used to elucidate the cause behind the difference in catalysis caused by catalyst supports. First, factors closely associated with the first electron transfer of the ORR were assessed in the light of quantum chemistry. Then intermediate (atomic oxygen, O) adsorption strength on the catalyst surface was calculated. The results show that, in terms of minimum energy difference, the best orbital symmetry match, and the maximum orbital overlap, TiO2 does bring about a very positive effect on catalysts Pd/TiO2 for the first electron transfer of the ORR. Especially, TiO2 remarkably expands the space size of Pd/TiO2 HOMO orbital and improves orbital overlap of Pd/TiO2 HOMO and O2 LUMO. The analysis of deformation density and partial density of state shows that the strong interaction between Pt and Ti leads to a strong adsorption of intermediate O on Pt/TiO2, but the strong interaction between Pd and surface O causes positive net charge of Pd and a weak adsorption of intermediate O on Pd/TiO2. Thus, the ORR can proceed more smoothly on Pd/TiO2 than Pt/TiO2 in every respect of maximum orbital overlap and rate delay by intermediate O. The research also discloses that several factors lead to less activity of TiO2-supported Pt and Pd catalysts than the C-supported ones for the ORR. These factors include the poor dispersion of Pt and Pd particles on TiO2, poor electric conduction of TiO2 carrier itself, and bigger energy difference between HOMO of TiO2-carried metallic catalysts and LUMO of O2 molecule due to electrons deeply embedded in the semiconductor TiO2 carrier.

关键词： density function theory (DFT) catalyst-support interaction electrocatalysis oxygen reduction reaction (ORR) carbon TiO2

Wavelet packet decomposition entropy threshold method for discrete spectrum interferences rejection of on-line partial discharge monitoring

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Journal of Chongqing University 2003年第1期2卷 9-12页

作者：唐炬 sun caixin SONG Shengli LI Jian The Key Laboratory of High Voltage Engineering and Electrical New Technology Under the Ministry of Education Chongqing UniversityChongqing 400044P.R.China

The frequency domain division theory of dyadic wavelet decomposition and wavelet packet decomposition (WPD) with orthogonal wavelet base frame are presented. The WPD coefficients of signals are treated as the outputs of equivalent bandwidth filters with different center frequency. The corresponding WPD entropy values of coefficients increase sharply when the discrete spectrum interferences (DSIs), frequency spectrum of which is centered at several frequency points existing in some frequency region. Based on WPD, an entropy threshold method (ETM) is put forward, in which entropy is used to determine whether partial discharge (PD) signals are interfered by DSIs. Simulation and real data processing demonstrate that ETM works with good efficiency, without pre-knowing DSI information. ETM extracts the phase of PD pulses accurately and can calibrate the quantity of single type discharge.

关键词： partial discharge(PD) discrete spectrum interference(DSI) wavelet packet decomposition(WPD) entropy

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火工品压药压力的控制新方法

机械工程学报 2008年第6期44卷 219-223页

作者：郑连清孙才新重庆大学输配电装备及系统安全与新技术国家重点实验室重庆400044

有效而精确地控制压药压力是保证火工品质量的重要工艺手段。针对火工品药剂对象压力控制是典型的非线性控制,传统的控制方法无法满足要求的问题,采用仿人智能控制理论解决火工品药剂对象压力的控制,提出基于误差信息空间(e,(?))相平面... 详细信息

有效而精确地控制压药压力是保证火工品质量的重要工艺手段。针对火工品药剂对象压力控制是典型的非线性控制,传统的控制方法无法满足要求的问题,采用仿人智能控制理论解决火工品药剂对象压力的控制,提出基于误差信息空间(e,(?))相平面设计仿人智能控制器的思想,建立并设计基于仿人智能的火工品药剂压药控制模型。该系统模型的突出特点为:在线适应和实时控制能力强,具有学习、记忆和推理的能力。进行实际产品生产试验,结果表明该方法能解决火工品药剂对象压药压力的高精度无超调控制的关键问题,产品一致性好。

关键词：火工品药剂压药压力控制误差相平面仿人智能控制

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海上风电机组国产化研究与实践

发电技术 2023年第5期44卷 696-702页

作者：孙财新张波唐巍周昳鸣付明志秦猛郭小江中国华能集团清洁能源技术研究院有限公司北京市昌平区102218

统计并分析了海上风电机组叶片、主轴、电气系统、控制系统等关键部件和系统的技术现状及国产化状态,针对目前海上风电机组部件与系统中存在的国产化弱项,采用理论分析、材料/部件选型、部件研制、测试验证、整体组装的思路,进行叶片、... 详细信息

统计并分析了海上风电机组叶片、主轴、电气系统、控制系统等关键部件和系统的技术现状及国产化状态,针对目前海上风电机组部件与系统中存在的国产化弱项,采用理论分析、材料/部件选型、部件研制、测试验证、整体组装的思路,进行叶片、主轴承、变流器、可编程逻辑控制器(programmable logic controller,PLC)等部件和系统的国产化研制,并采用研制的国产化部件和系统进行5 MW国产化海上风电机组装配,该机组的国产化率达到95%以上。结果表明:海上风电机组的大部分部件与系统具备国产化条件,部分设计(如叶片设计等)所用工业软件仍依赖进口,少部分核心元器件国内仍然缺失。

关键词：海上风电国产化风电机组叶片主轴承可编程逻辑控制器(PLC)控制系统