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IEEE Energy Conversion Congress and Exposition

作者： Yuting Gao Ronghai Qu Dawei Li Jian Li Yongsheng Huo State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9781509007387

In this paper, a novel flux reversal machine (FRM) is proposed to achieve a larger torque density and a smoother torque waveform than the conventional FRM. The proposed FRM have the same combinations of stator and rotor slots, winding pole pair and PM usage, but different PM arrangement with the conventional FRM, i.e. in the conventional FRM, a pair of PMs is mounted on the surface of each stator teeth, while the PMs of the proposed FRM are uniformly attached to the entire inner surface of the stator. First, the origination from the conventional FRM to the proposed FRM is introduced. Then, the effects of the rotor slot number, split ratio, stator/rotor slot opening ratio, PM thickness and pole arc on average torque and cogging torque are investigated and analyzed, which give a reasonable prediction for maximum achievable power density and minimum possible cogging torque of the proposed FRM. Moreover, the proposed FRM is compared to a conventional FRM in terms of back-EMF, cogging torque, rated torque, torque ripple and overload capabilities. Finally, a 12-stator-slot/17-rotor-slot FRM prototype is built to verify the theoretical analyses.

关键词： permanent magnet Cogging torque flux reversal machine (FRM) torque density

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advanced high torque density non-overlapping winding PM vernier machines

Advanced high torque density non-overlapping winding PM vern...

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IEEE Energy Conversion Congress and Exposition

作者： Tianjie Zou Dawei Li Ronghai Qu Jian Li Dong Jiang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical & Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9781509007387

In recent years, permanent magnet (PM) vernier machines have gained more and more attentions due to their high torque density and simple mechanical structure. However, vernier PM machines with lap windings always suffer from long end winding length, and regular non-overlapping winding may result in torque reduction for PM vernier (PMV) machines. In this paper, an advanced PM vernier (APMV) machine topology with multi working permeance harmonics is proposed. This topology is equipped with non-overlapping winding, i.e. short end winding length, and could achieve ～20% higher torque density than that of regular non-overlapping winding PMV machine, with the same magnet usage. Furthermore, both the theoretical analysis and finite element algorithm (FEA) are used to study the performances of this topology, such as back EMF, output torque as well as structure parameter effect. Finally, analysis results are verified by experimental test on a 21Nm prototype, which is designed to have similar volume and weight with a 14Nm regular commercial PM machine.

关键词： torque density Vernier PM machine non-overlapping winding permeance harmonic

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Harmonic components based protection strategy for inverter-interfaced AC microgrid

Harmonic components based protection strategy for inverter-i...

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IEEE Energy Conversion Congress and Exposition

作者： Zhi Chen Xuejun Pei Li Peng State Key Laboratory of Advanced Electromagnetic Engineering and Technology (AEET) Huazhong University of Science and Technology (HUST) Wuhan Hubei China

ISBN: (纸本)9781509007387

In the inverter-interfaced AC microgrid (IIAM), when a short-circuit fault occurs at the distribution line, the output fault current of inverter is commonly limited to two times over its rated current due to the limited overcurrent capacity of power electronic device. Therefore, the conventional overcurrent protection principle cannot be applied to IIAM. Aiming at addressing this issue, a new protection method based on the low harmonics components is proposed in this paper. Through injecting a certain proportion of fifth harmonics to the fault current, the protection device can detect the fault according to the low harmonics components extracted by the digital relay (DR). This scheme does not rely on the large fault current. Therefore, some limitations of the traditional overcurrent protection are avoided. The corresponding experiments were carried out with two 10kVA parallel-connected inverters supply system, and the results proved the feasibility of this approach.

关键词： harmonic components Inverter-interface microgrid short-circuit fault overcurrent protection

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On the positive upward leader in response to downward stepped leader in a 10m rod-to-rod long air gap

On the positive upward leader in response to downward steppe...

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International Conference on Lightning Protection (ICLP)

作者： Hengxin He Junjia He Xiangen Zhao Weijiang Chen Franco'D Alessandro State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan Hubei CN State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Grid Corporation of China Beijing China PhysElec Solutions Hobart Australia

ISBN: (纸本)9781509048434

Long negative sparks have been widely used to investigate the lightning attachment process of grounded structures. The rod-to-rod air gap is one of the most common configurations used in laboratory experiments to investigate the characteristics of the positive upward leader in response to the negative descending leader steps. In the research presented in this paper, experimental observations have been carried out in a 10 m rod-to-rod air gap. Many discharge parameters were recorded using a high speed camera, wideband current measurement devices and Pockels electric field sensors. It was found that the average linear charge density of a negative leader is about 142μC/m, which is close to the charge density of a natural lightning downward leader delivering a stroke current of about 7kA. The maximum upward streamer and leader lengths are 2.24 m and 0.64 m, respectively. The space E-field En in negative long sparks consists of a series of electric field steps. Although the dEn/dt is relatively high during the formation of each negative leader step, the dEn/dt decreases significantly and the upward leader stops elongation during the time interval of two negative leader steps. As a consequence, the velocity and length of the upward leader initiation by negative long sparks might only be close to the initiation stage under natural lightning conditions.

关键词： Partial discharges TV Decision support systems Discharges (electric) Electric fields Lightning protection Air gaps

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Torque ripple reduction techniques for stator DC winding excited vernier reluctance machines

Torque ripple reduction techniques for stator DC winding exc...

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IEEE Energy Conversion Congress and Exposition

作者： Mengxuan Lin Ronghai Qu Jian Li Shaofeng Jia Yang Lu State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9781509007387

Stator DC winding Excited Vernier Reluctance Machines (DC-VRMs) are a kind of novel machines, which are investigated more and more owing to absence of expensive permanent magnet material. However, DC-VRMs are found to have large torque ripple if they are not carefully designed. There are a lot of existing methods to reduce the cogging torque in permanent magnet (PM) machines, but the design techniques for DC-VRMs have only been mentioned recently in few papers. In this paper, some new methods are proposed including shifted rotor tooth, stepped rotor skewing with multiple modules, T-shape rotor tooth, various rotor tooth arc, rotor tooth-chamfering, different length of air gap, and these methods are based on the techniques for PM machines to reduce torque ripple. The influence of the proposed methods on torque ripple is examined by using Finite Element Analysis (FEA) and it is found that the torque ripple can be reduced significantly.

关键词： various rotor tooth arc Cogging torque DC-VRMs FEA rotor tooth torque ripple vernier machine doubly salient structure stator and rotor tooth combinations T-shape rotor tooth shifted rotor tooth

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Hybrid excited vernier PM machines with novel DC-biased sinusoidal armature current

Hybrid excited vernier PM machines with novel DC-biased sinu...

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IEEE Energy Conversion Congress and Exposition

作者： Shaofeng Jia Ronghai Qu Jian Li Dawei Li Haiyang Fang State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

ISBN: (纸本)9781509007387

In this paper, a novel class of hybrid excitation, stator vernier permanent magnet (VPM) machines (HE-VPM) are proposed. The proposed machines are with salient rotor structure, stator located PMs, and concentrated armature windings. Therefore, the superiority of the proposed machine is robust rotor structure, short and non-overlapping end-winding, and easy heat dissipation. Besides, a novel DC-biased sinusoidal current, which contains an alternating current (AC) component and a direct current (DC) component, is applied, with this novel current, a novel hybrid excited VPM machines without additional field windings are obtained. The simulation results shows that the proposed machines exhibit higher torque density, power factor, and efficiency, Also, the constant power operation range is broadened, as the injected DC biased current can weaken or enhance the exciting fields at high/low speed. Finally, a prototype has been designed and under built, and the corresponding experiments will be added later.

关键词： vernier PM machines Fractional slot concentrated winding hybrid excited stator PM machines sinusoidal current with DC-biased

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Improved direct torque control based modified torque controller for surface-mounted permanent magnet synchronous machines

Improved direct torque control based modified torque control...

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IEEE International Conference on Industrial technology (ICIT)

作者： Fengxiang Chen Wei Xu Md Rabiul Islam State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology China Department of Electrical and Electrical Engineering Rajshahi University of Engineering and Technology Bangladesh

In this paper, it proposes an improved space vector modulation (SVM) based direct torque control (DTC) algorithm with modified torque controller for surface-mounted permanent magnet synchronous machines (SPMSMs). First, it introduces the conventional SVM-DTC for SPMSM and then analyzes its potential shortcomings to be overcame. Second, an improved SVM-DTC control algorithm with a modified torque controller has been put forward to further enhance the drive performance of SPMSM, such as dynamic response and stable smoothness of torque. Third, with comparison of the conventional SVM-DTC algorithms, the SPMSM torque and flux ripples based on the new strategy are reduced obviously. Comprehensive simulations validate relevant theoretical analysis.

关键词： Torque Mathematical model Stators Permanent magnet machines Voltage control electromagnetics Aerospace electronics

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Optimization scheduling model based on source-load-energy storage coordination in power systems

Optimization scheduling model based on source-load-energy st...

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International Conference on Automation and Computing (ICAC)

作者： Yaowang Li Shihong Miao Xing Luo Jihong Wang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science & Technology China School of Engineering University of Warwick U.K.

To improve the wind power and photovoltaic power accommodation rate and reduce the power system operation costs, this paper considers thermal power units, price-based demand response (DR) and battery energy storage system (BESS) as scheduling resources and establishes an optimization scheduling model based on source, load and energy storage coordination. A two stages optimization method is proposed in order to minimize the system operational costs including thermal power units operation cost, wind power and photovoltaic power curtailment cost and price-based DR scheduling costs. The first stage optimization uses binary particle swarm optimization algorithm (BPSO) to minimize the sum of wind power and photovoltaic power curtailment cost and thermal power units start-up cost. Based on the optimization results at the first stage, the second stage optimization uses double layers' continuous particle swarm optimization (CPSO) algorithm to minimize the sum of price-based DR scheduling cost and fuel consumption cost. The simulation results verify the feasibility and effectiveness of this optimization scheduling model.

关键词： Photovoltaic systems Wind power generation Optimal scheduling Load modeling Power systems

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Radial magnetic field in magnetic confinement device

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Chinese Physics B 2015年第9期24卷 337-342页

作者：熊昊刘明海陈明饶波陈杰陈兆权肖金水胡希伟 State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology School of Electrical and Electric Engineering Huazhong University of Science and Technology College of Electrical and Information Engineering Anhui University of Science and Technology

The intrinsic radial magnetic field（B r） in a tokamak is explored by the solution of the Grad–Shafranov equation in axisymmetric configurations through an expansion of the four terms of the magnetic surfaces. It can be inferred from the simulation results that at the core of the device, the tokamak should possess a three-dimensional magnetic field configuration, which could be reduced to a two-dimensional one when the radial position is greater than 0.6a. The radial magnetic field and the amzimuthal magnetic field have the same order of magnitude at the core of the device. These results can offer a reference for the analysis of the plasma instability, the property of the core plasma, and the magnetic field measurement.

关键词： radial magnetic field minor toroidal coordinate three-dimensional magnetic field configuration

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Real-time Dispatch with Risk Considerations for Wind Power Integrated System Aiming at Security-economy Coordination

Real-time Dispatch with Risk Considerations for Wind Power I...

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2016 International Conference on Electrical engineering and Automation（ICEEA2016）

作者： Jian SHAO Jia-si WU Wei LIU Xin-dong ZHAO Wei DAI Bu-han ZHANG Jiangsu Electric Power Company Research Institute State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology

In order to ensure wind power accommodation with security constraints, the active power real-time dispatch for wind power integrated system need to handle the contradiction between intermittent wind power and power network security, aiming at security-economy ***, the mathematical uncertainty models of wind power and N-1 transmission line faults are constructed, and a risk-based decision-making model for real-time dispatch is proposed based on probability and criticality analysis of stochastic disturbance, which reducing the total risk under different operation conditions in the future period. And the simulation results of 30-bus test system verified the rationality and effectiveness of the proposed method.

关键词： Wind power Real-time dispatch Security-economy coordination Risk

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