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The influences of silane coupling agents on the heat and moisture resistance of basalt fibre-reinforced composites

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High Voltage 2023年第1期8卷 38-47页

作者： Yunpeng Liu Mingjia Zhang Hechen Liu Yu Sun Wanxian Wang Jie Liu Hebei Provincial Key Laboratory of power Transmission Equipment Security Defence North China Electric Power UniversityBaodingChina State Key Laboratory of Alternate electrical power System with Renewable Energy Sources North China Electric Power UniversityBaodingChina State Grid Hebei electric power Company electric power research institute ShijiazhuangChina

Basalt fibre composite materials have shown good application prospects in electrical equipment,but their reliability can be affected by damp-heat *** this work,the interface,mechanical,and electrical properties of basalt fibre composites treated with three coupling agents via damp-heat ageing were *** simulations were conducted to reveal the damp-heat ageing mechanism of the *** results show thatγ-aminopropyl triethoxy silane(KH-550)andγ-glycidoxy propyl trimethoxy silane(KH-560)perform better as coupling agents as they form bonds with the matrix resin,compared withγ-methacryloxy propyl trimethoxy silane(KH-570).After the dampheat ageing treatment,the hydrolysis of the defects of the amino groups in the interface of the KH-550-treated sample can weaken its mechanical properties and insulation properties *** interface layer of the KH-560-treated sample is mostly composed of carbon–oxygen single bonds and methylene groups with its interface structure more stable,which endows the sample with better stability of its mechanical and insulating ***,KH-560 is a more suitable coupling agent for processing basalt fibres to be used in electrical equipment.

关键词： composites coupling fibre

Future evolution of automated demand response system in smart grid for low-carbon economy

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Journal of Modern power Systems and Clean Energy 2015年第1期3卷 72-81页

作者： Huaguang YAN Bin LI Songsong CHEN Ming ZHONG Dezhi LI Limin JIANG Guixiong HE china electric power research institute Beijing 100192China School of electric and Electronic Engineering North China Electric Power UniversityBeijing 102206China

Smart grid construction is an important carrier and an effective way to promote the development of lowcarbon *** response(DR)is commonly regarded as an important core technology in smart grid field,and it reflects the flexible and interactive features of the core business in smart *** is the developing direction of automated demand response(ADR)technology,and its main features are the standardization of information exchange,together with the intelligence of decision-making and the automation of *** technology can improve the efficiency of the whole power system and enhance the ability to accept new energy *** paper analyzes the role of demand response in improving efficiency and low-carbon energy saving power *** automated demand response system architecture is investigated,and the ADR roadmap of commercial/industrial and residential customer is *** key technologies for ADR system are analyzed,including demand response strategy,information exchanging model,measurement and verification techniques,and multi-agent scheduling *** ensure the interoperability between the grid side and the user side,the ADR business in smart grid user interface standards is concluded to support further demand side management project.

关键词： Demand response Information model System architecture Load shifting

Wear Analysis of Disc Cutters of Full Face Rock Tunnel Boring Machine

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Chinese Journal of Mechanical Engineering 2014年第6期27卷 1294-1300页

作者： ZHANG Zhaohuang MENG Liang SUN Fei School of Energy Power and Mechanical Engineering North China Electric Power University Foreign Languages School North China Electric Power University

Wear is a major factor of disc cutters’ failure. No current theory offers a standard for the prediction of disc cutter wear yet. In the field the wear prediction method commonly used is based on the excavation length of tunnel boring machine（TBM） to predict the disc cutter wear and its wear law, considering the location number of each disc cutter on the cutterhead（radius for installation）; in theory, there is a prediction method of using arc wear coefficient. However, the preceding two methods have their own errors, with their accuracy being 40% or so and largely relying on the technicians’ experience. Therefore, radial wear coefficient, axial wear coefficient and trajectory wear coefficient are defined on the basis of the operating characteristics of TBM. With reference to the installation and characteristics of disc cutters, those coefficients are modified according to penetration, which gives rise to the presentation of comprehensive axial wear coefficient, comprehensive radial wear coefficient and comprehensive trajectory wear coefficient. Calculation and determination of wear coefficients are made with consideration of data from a segment of TBM project（excavation length 173 m）. The resulting wear coefficient values, after modification, are adopted to predict the disc cutter wear in the follow-up segment of the TBM project（excavation length of 5621 m）. The prediction results show that the disc cutter wear predicted with comprehensive radial wear coefficient and comprehensive trajectory wear coefficient are not only accurate（accuracy 16.12%） but also highly congruous, whereas there is a larger deviation in the prediction with comprehensive axial wear coefficient（accuracy 41%, which is in agreement with the prediction of disc cutters’ life in the field）. This paper puts forth a new method concerning prediction of life span and wear of TBM disc cutters as well as timing for replacing disc cutters.

关键词： full face rock tunnel boring machine disc cutter radial wear coefficient axial wear coefficient trajectory wear coefficient

Multi‐type defect detection and location based on non‐destructive impedance spectrum measurement for underground power cables

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High Voltage 2023年第5期8卷 977-985页

作者： Jingang Su Liqiang Wei Peng Zhang Yan Li Yunpeng Liu electric power research institute of State Grid Hebei electric power Supply Co.Ltd. ShijiazhuangChina School of electrical and Electronic Engineering North China Electric Power UniversityBaodingChina

power cable defect detection and location is a crucial aspect in power asset *** spectrum measurement can be used as a non‐destructive tool for cable *** from overheating and moisture ingress are investigated by the authors,and it is shown that multi‐type cable defects can be detected and located by this *** both electromagnetic analysis and experimental investigation,the relation between impedance variation and the dielectric permittivity is studied to reveal the method's *** approach to implement such impedance measurement online is proposed and its perspectives in terms of sensitivity is investigated by field scale *** is shown that 2%impedance variation due to defect should be *** scale tests show perspectives for online application with signal coupling through a highfrequency current transformer with focus on the differences in waveforms obtained from the impedance measurements.

关键词： power impedance defect

Rock deformation equations and application to the study on slantingly installed disc cutter

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Acta Mechanica Sinica 2014年第4期30卷 540-546页

作者： Zhao-Huang Zhang Liang Meng Fei Sun School of Energy Power and Mechanical EngineeringNorth China Electric Power University School of Foreign Languages North China Electric Power University

At present the mechanical model of the interac- tion between a disc cutter and rock mainly concerns indentation experiment, linear cutting experiment and tunnel boring machine （TBM） on-site data. This is not in line with the actual rock-breaking movement of the disc cutter and impedes to some extent the research on the rock-breaking mechanism, wear mechanism and design theory. Therefore, our study focuses on the interaction between the slantingly installed disc cutter and rock, developing a model in accordance with the actual rock-breaking movement. Displacement equations are established through an analysis of the velocity vector at the rock-breaking point of the disc cutter blade; the func- tional relationship between the displacement parameters at the rock-breaking point and its rectangular coordinates is established through an analysis of micro-displacement vectors at the rock-breaking point, thus leading to the geometric equations of rock deformation caused by the slantingly installed disc cutter. Considering the basically linear relationship between the cutting force of disc cutters and the rock deformation before and after the leap break of rock, we express the constitutive relations of rock deformation as generalized Hooke＇s law and analyze the effect of the slanting installa- tion angle of disc cutters on the rock-breaking force. This will, as we hope, make groundbreaking contributions to the development of the design theory and installation practice of TBM.

关键词： TBM Disc cutter· Geometric equation Slant-ingly installed Rock-breaking

The feasibility of continuous basalt fibre-reinforced polymer application to composite cross-arms

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High Voltage 2023年第3期8卷 590-598页

作者： Yunpeng Liu Mingjia Zhang Hechen Liu Yunfan Ma Wanxian Wang Xiaohan Dai Jie Liu Hebei Provincial Key Laboratory of power Transmission Equipment Security Defence North China Electric Power UniversityBaodingChina State Key Laboratory of Alternate electrical power System with Renewable Energy Sources North China Electric Power UniversityBaodingChina State Grid Hebei electric power Company electric power research institute ShijiazhuangChina

Composite cross-arms have the advantages of high lightning resistance but impose onerous requirements on mechanical and insulation *** glass fibre composites fail to meet the needs of practical *** fibre exhibits better mechanical properties and stability than glass fibre and has potential application *** study aims to evaluate the feasibility of its application to composite *** mechanical,electrical,and physical properties of basalt fibre-reinforced polymer(BFRP)were investigated and compared with glass fibre-reinforced polymer(GFRP).The results indicate that BFRP has better thermal stability and mechanical properties than *** them,the temperature at the maximum weight loss rate of BFRP is 14℃ higher than that of GFRP,and the tensile and flexural modulus of BFRP is 43%and 29%higher than those of ***,the dielectric losses of BFRP and GFRP at 50 Hz are 2%,and the breakdown field strength is 22 kV/mm,both of which have the same insulation *** meets the requirements of composite cross-arm for quality and reliability to ensure the safety and stability of transmission ***,the interlaminar shear test and SEM show weak interfacial bonding strength between basalt fibre and ***,micro-computed tomography scanning of BFRP and GFRP and 3D construction of their internal microstructures indicate that the pore defect content of BFRP reaches 0.034%,which far exceeds that of *** findings show that the wettability and adhesion between basalt fibre and resin must be *** special sizing agents for basalt fibre is necessary further to improve the mechanical and electrical properties of BFRP.

关键词： fibre basalt composite

Design Theory of Full Face Rock Tunnel Boring Machine Transition Cutter Edge Angle and Its Application

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Chinese Journal of Mechanical Engineering 2013年第3期26卷 541-546页

作者： ZHANG Zhaohuang MENG Liang SUN Fei School of Energy Power and Mechanical Engineering North China Electric Power University School of Foreign Languages North China Electric Power University

At present, the inner cutters of a full face rock tunnel boring machine (TBM) and transition cutter edge angles are designed on the basis of indentation test or linear grooving test. The inner and outer edge angles of disc cutters are characterized as symmetric to each other with respect to the cutter edge plane. This design has some practical defects, such as severe eccentric wear and tipping, etc. In this paper, the current design theory of disc cutter edge angle is analyzed, and the characteristics of the rock-breaking movement of disc cutters are studied. The researching results show that the rotational motion of disc cutters with the cutterhead gives rise to the difference between the interactions of inner rock and outer rock with the contact area of disc cutters, with shearing and extrusion on the inner rock and attrition on the outer rock. The wear of disc cutters at the contact area is unbalanced, among which the wear in the largest normal stress area is most apparent. Therefore, a three-dimensional model theory of rock breaking and an edge angle design theory of transition disc cutter are proposed to overcome the flaws of the currently used TBM cutter heads, such as short life span, camber wearing, tipping. And a corresponding equation is established. With reference to a specific construction case, the edge angle of the transition disc cutter has been designed based on the theory. The application of TBM in some practical project proves that the theory has obvious advantages in enhancing disc cutter life, decreasing replacement frequency, and making economic benefits. The proposed research provides a theoretical basis for the design of TBM three-dimensional disc cutters whose rock-breaking operation time can be effectively increased.

关键词： disc cutter three-dimensional mode edge angle full face rock tunnel boring machine (TBM) flat-face cutterhead

The comparative analysis of rocks' resistance to forward-slanting disc cutters and traditionally installed disc cutters

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Acta Mechanica Sinica 2016年第4期32卷 690-695页

作者： Zhao-Huang Zhang Sun Fei Meng Liang School of Energy Power and Mechanical EngineeringNorth China Electric Power University School of Foreign Languages North China Electric Power University

At present, disc cutters of a full face rock tunnel boring machine are mostly mounted in the traditional way. Practical use in engineering projects reveals that this installation method not only heavily affects the operation life of disc cutters, but also increases the energy consumption of a full face rock tunnel boring machine. To straighten out this issue, therefore, a rock-breaking model is developed for disc cutters＇ movement after the research on the rock breaking of forward-slanting disc cutters. Equations of its displacement are established based on the analysis of velocity vector of a disc cutter＇s rock-breaking point. The functional relations then are brought forward between the displacement parameters of a rock-breaking point and its coordinate through the analysis of micro displacement of a rock-breaking point. Thus, the geometric equations of rock deformation are derived for the forward-slanting installation of disc cutters. With a linear relationship remaining between the acting force and its deformation either before or after the leap breaking, the constitutive relation of rock deformation can be expressed in the form of generalized Hooke law, hence the comparative analysis of the variation in the resistance of rock to the disc cutters mounted in the forward-slanting way with that in the traditional way. It is discovered that with the same penetration, strain of the rock in contact with forwardslanting disc cutters is apparently on the decline, in otherwords, the resistance of rock to disc cutters is reduced. Thus wear of disc cutters resulted from friction is lowered and energy consumption is correspondingly decreased. It will be useful for the development of installation and design theory of disc cutters, and significant for the breakthrough in the design of full face rock tunnel boring machine.

关键词： installed breaking installation rock apparently tunnel traditionally decline remaining brought

Adaptive resource allocation for multi-user multi-server power-line communication OFDM systems

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Journal of Central South university 2011年第2期18卷 479-489页

作者：徐志强翟明岳崔翔赵宇明 Hunan electric power Test and research institute Department of electric and Electron Engineering North China Electric Power University Technology research Center of china Southern power Grid

The bits and power allocation model of adaptive power-rate mixture for multi-user multi-server power-line communication systems was analyzed with the restrictions of maximal total power,fixed rate for each real time (RT) user,minimal rate for each non-real time (NRT) user,maximal bits and power for each subcarrier in each orthogonal frequency division multiplexing (OFDM) symbol. An algorithm of resource dynamic allocation in the first OFDM symbol of each frame and resource optimal adjustment in the latter OFDM symbol of each frame was proposed. In the first OFDM symbol of every frame,resource is firstly assigned for RT users so as to minimize their total used power until satisfying their fixed rates; secondly the remainder resource of power and subcarriers are assigned for NRT users so as to minimize their total used power until satisfying their minimal rates also; lastly the remainder resource is again assigned for NRT users according to the proportional fairness strategy so as to maximize their total assigning rate. In the latter OFDM symbol of each frame,bits are swapped and power is adjusted for every user based on the resource allocation results of anterior OFDM symbol. The algorithm is tested in the typical power-line channel scenarios and the simulation results indicate that the proposed algorithm has better performances than the classical multi-user resource allocation algorithms and it realizes the multiple aims of multi-user multi-server resource allocation for power-line communication systems.

关键词： power-line communications adaptive orthogonal frequency division multiplexing resource allocation user priority swapadjustment