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IEEE Electrical Insulation Conference

作者： Fei Lu Lei Jin Siwei Liu Yi Liu Hua Li Fuchang Lin State Grid Key Laboratory of On-site Test Technology on High Voltage Power Apparatus State Grid Hubei Electric Power Research Institute State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science & Technology

ISBN: (纸本)9781467387071

Structural faults detection of power transformers are quite significant, and general diagnosis based on different test and simulation methods is commonly used to detect mechanical and/or electrical faults in power transformers. In this paper, the diagnosis of the transformer winding axial displacement faults based on FEM simulation and on-site experiment is carried out and presented. Based on the FEM simulation, it is necessary to analyze the effect of the axial displacement faults on the change of the electrical parameters. The whole winding's or the single disk's axial displacement are under consideration, and different fault levels are taken into consideration in the simulation analysis to investigate the influence of axial displacement on the electrical parameters. Using the calculated parameters, a distributed model of the power transformer based on ATP/EMTP is present to study the performance of frequency response curve on the axial displacement with different fault levels. The operating states of several 110 kV power transformers are tracked, and a typical transformer after the short-circuit impact is tested. The FRA test results are obtained before and after the short-circuit impact. The simulation results and the on-site test results are compared, and they show a better consistency. It can be concluded that under the typical impact of the axial displacement, the frequency response curve starts an obvious variation from 150 kHz, and the resonances and anti-resonances are shifted to the high frequency direction. The overall fault detection results show that the proposed method can discriminate the winding axial displacement fault with the high hit ratio.

关键词： Power transformer Frequency response analysis Axial displacement Winding deformation Finite element method

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Vernier reluctance dual-stator inner-rotor machines with semi-closed slot

Vernier reluctance dual-stator inner-rotor machines with sem...

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International Conference on Electrical Machines and Systems (ICEMS)

作者： Linyuan Xiao Jian Li Ronghai Qu Dawei Li Yuting Gao State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology China

ISBN: (纸本)9781479988068

This paper proposes vernier reluctance dual-stator machines with semi-closed slot. The structure of vernier reluctance dual-stator machines with semi-closed slot is firstly given, followed by a comprehensive comparison with the conventional structure in aspects of no load flux linkage, cogging torque and torque. The effect of inner stator shift on the performance of vernier reluctance dual-stator machines with semi-closed slot is also analyzed.

关键词： Torque Stators Couplings Forging Decision support systems electromagnetics Reluctance machines

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A novel axial flux switched reluctance motor with grain oriented electrical steel

A novel axial flux switched reluctance motor with grain orie...

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International Conference on Magnetics (INTERMAG)

作者： J. Ma R. Qu J. Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan

Switched reluctance motor (SRM) has been widely used in automobile and aerospace for its fault tolerance and simple construction [1]. According to the direction of magnetization, SRM can be classified as radial flux and axial flux types. Axial flux switched reluctance motor (AFSRM) with its flat shape and high aspect ratio is regarded to be suitable for in-wheel motor applications. An axial flux segmented rotor-switched reluctance motor topology is suggested in [2] to increase active surface area for the output torque within a confined space. However, torque and efficiency of the AFSRM are less than those of PMSM for the same frame size. To solve above problems, grain oriented electrical steel (GOES) could be used for AFSRM to improve the electromagnetic properties because the material has a good magnetic characteristic in the rolling direction. A design of AFSRM for traction application was proposed in [3]GOES has been used in stator to reduce leakage flux, divided segments in c-core structure may be a challenge to the joint strength of the structure.

关键词： Stators Steel Reluctance motors Rotors Torque electromagnetics Topology

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A control method for permanent-magnet synchronous motor with unbalanced cable resistor

A control method for permanent-magnet synchronous motor with...

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International Conference on Power Electronics Systems and Applications (ICPESA)

作者： Zou Xunhao Shenghua Huang Qin Zhuqian Xiaodong Hu Kan Guangqiang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology China

ISBN: (纸本)9781509000647

The three phase cable connecting the inverter and PMSM may be unbalanced in some situation such as the deep drilling platform. This paper presents the mathematical model of PMSM with unbalanced cable resistance. The traditional PI current regulator cannot work well within the situation. The hysteresis band controller can operate well because it's independent of load parameters but the switching frequency may be very high to get good performance, which is not suitable. So a novel proportional integral resonant controller is proposed to eliminate the harmonic current caused by the asymmetry of the stator resistance. From the results of the experiment, the mentioned control strategy proves to be appropriate for PMSM with unbalanced cable resistance.

关键词： Immune system Switches Resistors Analytical models Yttrium Space vector pulse width modulation

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New Current Control Method of DC Power Supply for Magnetic Perturbation Coils on J-TEXT

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Plasma Science and technology 2014年第11期16卷 1074-1078页

作者：曾武兵丁永华易斌许航宇饶波张明刘明海 State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology

In order to advance the research on suppressing tearing modes and driving plasma rotation, a DC power supply （PS） system has been developed for dynamic resonant magnetic perturbation （DRMP） coils and applied in the J-TEXT experiment. To enrich experimental phe- nomena in the J-TEXT tokamak, applying the circulating current four-quadrant operation mode in the DRMP DC PS system is proposed. By using the circulating current four-quadrant oper- ation, DRMP coils can be smoothly controlled without the dead-time when the current polarity reverses. Essential circuit analysis, control optimization and simulation of desired scenarios have been performed for normal current. Relevant simulation and test results are also presented.

关键词： DRMP power supply （PS） J-TEXT four-quadrant operation

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Pole ratio effect on performance of stator DC excited vernier reluctance machines

Pole ratio effect on performance of stator DC excited vernie...

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International Conference on Magnetics (INTERMAG)

作者： S. Jia R. Qu J. Li State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan

The novel vernier reluctance machines with DC field winding in stator (DC-VRMs) have the advantages of wide speed range due to the flexible exciting field by DC winding, robust rotor structure thanks to no PMs or windings on rotor similar to doubly salient machines. In this digest, the effect of ratio of rotor poles to stator armature winding poles on the electromagnetic performance, such as back-EMF, torque and torque ripple and so on are researched based on six machines, which stator/rotor slot number are 12/7, 12/10, 12/11, 12/14, 12/16, 12/17, respectively and the corresponding pole ratio are 7/1, 10/4, 11/5, 14/4, 16/2 and 17/1, respectively . It is found that, the average torque is mainly determined by the ratio of rotor poles to stator armature winding poles in a certain region . For torque ripple, it is mainly affected by the least common multiple (LCM) of the number of stator and rotor slots . For example, 12/17 exhibits the lowest (1 .4%) while the 12/16 is largest (80%) .

关键词： Windings Stator windings Rotors Torque Reluctance machines

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A novel initial rotor position detection method for PM synchronous motors

A novel initial rotor position detection method for PM synch...

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International Conference on Power Electronics Systems and Applications (ICPESA)

This paper presents a novel initial rotor position estimation method for PM synchronous motors in EV application based on high frequency voltage injection. Mathematical model of PMSM are presented. Instantaneous current value rather than the amplitude of the corresponding current is utilized to calculate the rotor position. The filter to get the amplitude of the current is not needed and the accuracy of the result is irrelevant with the amplitude and frequency of the injected voltage. From the results of the experiment, the mentioned technique proves to be appropriate for initial rotor position detection of PMSM.

关键词： Synchronous motors Rotors Saturation magnetization Biographies Generators

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Plasma Response to Supersonic Molecular Beam Injection in J-TEXT

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Plasma Science and technology 2014年第1期16卷 17-20页

作者：肖金水杨州军庄革胡启明冯先德刘明海 State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology

Recently, hydrogen fueling experiments with supersonic molecular beam injection （SMBI） system have been performed in the J-TEXT tokamak. To evaluate the effects of the in- jection amount of SMBI on plasma behaviors, moderate and intensive SMBs have been separately injected and compared with each other in Ohmic discharges. With moderate SMBs, electron den- sity increases about twice as before, the size of magnetic island slightly decreases, and the edge toroidal rotation speed in a counter-current direction, measured by a high resolution spectrometer （Carbon V ion, 227.09 nm, r/a-= 0.7-0.8）, is accelerated from 8 km/s to 12 km/s. The state of higher electron density with moderate SMBI can be maintained for a long period, which indicates that plasma confinement is improved. However, with intensive SMBs, the accompanied magne- tohydrodynamic （MHD） activities are triggered, and the electron density increases moderately. The edge toroidal velocity is decreased, in certain cases even reversed in the co-current direction. The statistical result of experimental data for moderate and intensive SMBs suggests a preferred fueling amount （less than 3.2 ~ 1019） to improve the SMBI fueling efficiency in experiments.

关键词： SMBI fuelling plasma responses J-TEXT

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Evaluation of the calculation method for stray losses in structural parts of HVDC converter transformers

Evaluation of the calculation method for stray losses in str...

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International Conference on Electric Utility Deregulation and Restructuring and Power Technologies (DRPT)

作者： Yaqing Liu Dandan Zhang Zhenbiao Li Qinqing Huang Menghu Li Bin Li Jian Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781467371070

Stray losses in structural parts are calculated separately during determining load losses of HVDC converter transformers, but the calculation method proposed by IEC 61378-2 standard shows significant difference from the experimental results. The nonlinearity, hysteresis losses, and frequency characteristic are thought as the sources of errors in this paper, and then an electromagnetic-circuit coupling FEM analysis is performed to investigate them. It is shown that the frequency characteristic of the stray losses is the major factor that causes the errors, and the material characteristic should be considered. The magnetic and nonmagnetic materials are suggested to be calculated separately.

关键词： Magnetic hysteresis Decision support systems IEC Standards Finite element analysis Analytical models Power industry HVDC transmission

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The risk-based assessment of static voltage stability issues with consideration of load and wind power uncertainties

The risk-based assessment of static voltage stability issues...

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Clemson University Power Systems Conference (PSC)

作者： Weisi Deng Buhan Zhang Hongfa Ding State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

ISBN: (纸本)9781479919529

The risk-based assessment is a new approach to the voltage stability assessment in power system. Under several uncertainties, the security risk of static voltage stability with considerable of wind power can be evaluated. In this paper, the Quasi-Monte Carlo (QMC) simulation is used to speed up Monte Carlo by improving the technical of sample generation. Besides, a new voltage stability index is defined, which reveal critical characteristics of static voltage stability. The local voltage stability margin (LVSM) considering the security risk at a forecasted operating point can be calculated to evaluate the voltage stability. Testing on a modified IEEE New England 39-bus system, results from the proposed method are compared agains the result from the conventional method. The proposed method's effectiveness and advantaged are demonstrated with the test results.

关键词： Power system stability Stability criteria Circuit stability Wind power generation Uncertainty Load flow

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