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International Conference on Electrical Machines

作者： Mengxuan Lin Dawei Li Yu Zhao Xiang Ren Ronghai Qu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China

Pole-changing line-start permanent magnet (LSPM) motors eliminate the braking torque during starting process. The pole-changing LSPM motors often starts with pole-decreasing way in order to synchronize successfully, however, the asynchronous torque in starting stage is reduced and winding factor in steady stage is also decreased. In this paper, a pole-increasing-start LSPM motor is studied. The asynchronous torque increases effectively by increasing pole pairs number during starting process but the speed cannot accumulate up to synchronous speed directly in starting stage. So the starting process should be divided into pole-increasing starting stage and steady pole pairs starting stage. The starting torque becomes larger effectively in early process and the synchronization capability even better compared with conventional LSPM motors. Furthermore, the starting performance and steady-state winding factor are compared between pole-increasing and pole-decreasing LSPM motors. Finite element analysis is carried out to show the performance differences of those two kinds of motors.

关键词： Pole-changing Line-start permanent magnet motors Pole-increasing Pole-decreasing Permanent magnet braking torque Finite element analysis Starting performance Steady-state performance

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Radiation synthesis and heavy metal ions removal of cellulose microsphere based adsorbent

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IOP Conference Series: Earth and Environmental Science 2019年第1期344卷

作者： J F Du Z Dong L Zhao School of Nuclear Technology and Chemistry & Biology Hubei University of Science and Technology Xianning 437100 China Referred to contribution equally State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

A novel cellulose-based adsorbent was successfully prepared by radiation induced grafting of glycidyl methacrylate onto the surface of cellulose microspheres, followed by epoxy ring-opening reaction to introduce iminodiacetic acid disodium (IDA). The characterization of the obtained adsorbent was investigated in detail. To evaluate the adsorption performance of the novel adsorbent in comparison with commercial adsorbent D850, batch and column mode adsorption experiments against Cu (II) and Ni (II) were conducted. The equilibrium time for Cu (II) and Ni (II) were 20 and 30 min, which is much shorter than that of commercial adsorbent. The adsorption capacity of the adsorbent for Cu (II) and Ni (II) reached 96.90 and 111.11 mg/g, respectively. Applicability of the novel adsorbent on the actual wastewater generated from electroplating plants was also investigated. It was found that the novel adsorbent possessed a higher adsorption/desorption velocity and broadly similar adsorption capacity with the commercial adsorbent, signifying the effective adsorption performance of the developed grafted adsorbent.

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Genetic-Algorithm-based analytical method of SMPM motors

Genetic-Algorithm-based analytical method of SMPM motors

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2017 IEEE International Electric Machines and Drives Conference, IEMDC 2017

作者： Jing, Libing Qu, Ronghai Kong, Wubin Li, Dawei Huang, Hailin State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan China College of Electrical Engineering and New Energy China Three Gorges University Yichang China

ISBN: (纸本)9781509042814

In this paper, an exact analytical method is developed to computer the air-gap magnetic field of surface-mounted permanent-magnet (SMPM) motors for valuating slotting effects accurately. In order to improve the flux density and reduce cogging torque, the genetic algorithm toolbox of Matlab is used to optimize the motor, in which the actual depth of slot, slot opening, the length of gap and pole-Arc to pole-pitch ratio are taken into account in the computation. Magnetic field distributions, induced back electromotive force (EMF) and optimized cogging torque computed from the proposed analytical method are compared with those issued from two-dimensional finite-element method (FEM), the comparison results are consistent and shows the correctness and effectiveness of the proposed analytical method. © 2017 IEEE.

关键词： Genetic algorithms

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An active capacitor converter for improving robustness of the ZCZ-type grid-connected inverter against grid impedance variation 32

An active capacitor converter for improving robustness of th...

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32nd Annual IEEE Applied Power Electronics Conference and Exposition, APEC 2017

作者： Zhou, Qingfeng Wang, Xuehua Ruan, Xinbo Teng, Yu Liu, Fuxin State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Jiangsu Key Laboratory of New Energy Generation and Power Conversion Nanjing University of Aeronautics and Astronautics Nanjing China

ISBN: (纸本)9781509053667

In the grid-connected system, the stability of the grid-connected inverter (GCI) often suffers from the grid impedance, especially when connected to a weak grid. Using an impedance-based stability analysis method, this paper proposes an active capacitor converter (ACC) in parallel at the point of common coupling (PCC) to reshape the grid impedance, making the ratio of the reshaped grid impedance to the output impedance of GCI satisfy the Nyquist stability criterion. The ACC can guarantee the GCI to have high stability-robustness against wide-range grid impedance variation with low additional power losses and high power factor. Experimental results on a 6-kW prototype confirm the validity of the theoretical analysis. © 2017 IEEE.

关键词： Electric inverters

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Finite Element Simulation of a ZnO Varistor Stressed by a 4/10μs Current Impulse

Finite Element Simulation of a ZnO Varistor Stressed by a 4/...

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International Conference on Lightning Protection (ICLP)

作者： Zhiyao Fu Junjia He Jiazheng Lu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China State Key Laboratory of Disaster Prevention & Reduction for Power Grid Transmission and Distribution Equipment State Grid Hunan Electric Power Company Disaster Prevention and Reduction Center Changsha China

When ZnO varistors are stressed by 4/10 μs current impulses, mechanical cracking occasionally occurs. Based on finite element method, an electro-thermal-mechanical simulation of a ZnO varistor exposed to a 4/10 μs current impulse is shown in the present paper focusing on temperature and thermal-induced mechanical stress distribution. The goal is to obtain a better understanding of the failure phenomenon under high current impulse with short duration. Conclusions of varistor design and manufacture are drawn after simulation analysis.

关键词： Varistors Stress Zinc oxide Temperature measurement II-VI semiconductor materials Nonhomogeneous media Temperature

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Simulation of Sensorless Control for the Start-up of Large-Scale Synchronous Condenser Using Static Frequency Converter

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IOP Conference Series: Earth and Environmental Science 2019年第1期223卷

作者： Li Li Hao Zuo Siyuan Guo Jin Wang Jiawei Zhao State Grid Hunan Electric Power Company Limited Research Institute Changsha 410007 China State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan 430074 China

In this paper, the structural characteristics of large synchronous condensers and the working principle of static frequency converter are studied firstly. Intermittent commutation and natural commutation are adopted by the inverter on the machine side in low-speed and high-speed stage respectively. Second, methods of sensorless control in different conditions are proposed. The initial rotor position is estimated through two methods, the terminal voltage method and the rotor-flux-oriented method. And similar methods are used in low-speed stage. Besides, phase-locked loop is used in high-speed. Finally, simulation models are established in PSCAD/EMDTC. The rotor-flux-oriented method used in standstill condition and low-speed stage shows better accuracy. And the phase-locked loop is also effective in high-speed stage. Therefore, the sensorless control methods are feasible.

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Design and Implementation of a Modular Multilevel Converter with Hierarchical Redundancy Ability for Electric Ship MVDC System

Design and Implementation of a Modular Multilevel Converter ...

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作者： Chen, Yu Li, Zuoyu Zhao, Shanshan Wei, Xiaoguang Kang, Yong State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China State Grid Smart Grid Research Institute Beijing102200 China

Modular multilevel converter (MMC) can be considered as a promising candidate for modern electric ship medium-voltage direct current (MVDC) power system due to its high-voltage quality, low switching loss, good expansibility, and good redundancy. As the voltage level in MVDC is much lower than that in high-voltage direct current case, the number of submodules (SMs) of MMC in MVDC system is also much less. Therefore, the SM failure will have more significant effect on the safety operation. Since uninterrupted operation is one of the most important requirements in electric ship application, the special redundancy design for MMC is required. This paper thus proposes an MMC system with hierarchical redundancy ability, aiming to guarantee the ride-through operation under SM failure. The 'hot-reserved' and 'cold-reserved' SMs are prepared in the MMC by compromising the faulty SM number, voltage and current stress of SMs, SM power loss, and so on, and the hierarchical redundancy strategy is divided into several progressive layers to ride through the SM failure in different cases. The pretreatment units are designed to realize the proposed hierarchical redundant strategy smoothly, and without changing the existent modulation and sort-and-selection strategies designed for normal condition. The proposed design is explained in this paper, and verified by a three-phase MMC simulation and a single-phase MMC prototype. © 2013 IEEE.

关键词： Redundancy

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Inductance-Emulating Control for DFIG-Based Wind Turbine to Ride-Through Grid Faults

Inductance-Emulating Control for DFIG-Based Wind Turbine to ...

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作者： Zhu, Donghai Zou, Xudong Deng, Lu Huang, Qingjun Zhou, Shiying Kang, Yong StateKey Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhan430074 China Wuhan NARI Limited Liability Company of State Grid Electric Power Research Institute Wuhan430074 China State Key Lab. of Disaster Prev. and Reduction for Pwr. Grid Transmission and Distribution Equipment Changsha410129 China

For doubly fed induction generator (DFIG)-based wind turbines, the rotor side of DFIG is prone to suffering from overcurrent during grid faults, due to large electromotive force (EMF) induced in the rotor circuit. To solve this problem, this paper proposes an inductance-emulating control strategy for DFIG-based wind turbine to suppress the postfault rotor current, thereby enhancing its low-voltage ride through capability. Under the proposed control strategy, once the grid fault is detected, the rotor side converter (RSC) is controlled to emulate an inductance. Furthermore, with proper inductance value, both the required rotor voltage and postfault rotor current can be reduced within the permissible ranges of RSC, thus the controllability of control system can be maintained during transient process. Moreover, the oscillation of electromagnetic torque can be effectively suppressed during transient state of both grid fault and fault recovery. Finally, the simulation and experimental results are presented to demonstrate the effectiveness of the proposed method. © 1986-2012 IEEE.

关键词： Wind turbines

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Analysis and design of power hardware-in-the-loop testing for 400-Hz inverters 12

Analysis and design of power hardware-in-the-loop testing fo...

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12th IEEE Conference on Industrial Electronics and Applications, ICIEA 2017

作者： Zhao, Yingying Dong, Wen Zou, Xudong Tong, Li Zhu, Guorong State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic Engineering Huazhong University of Science and Technology Wuhang China Zhejiang Electric Power Corporation Research Institute Hangzhou China Wuhan University of Technology Wuhan China

ISBN: (纸本)9781538621035

For the testing of 400-Hz inverters, a power hardware-in-the-loop (PHIL) platform is presented. However, the selections of power interface circuit parameters, such as filter of hardware interface (HI) and operating DC bus voltage of power amplifier (PA), remarkably affect the performance of the PHIL system. To solve this problem, an analytical and quantitative design method for power interface of PHIL is proposed. With the proposed design method, the relationships of the power interface circuit parameters and the PHIL system performances can be sufficiently taken into account and intuitively illustrated on a graph. Hence, the choices and optimizations of these parameters can be convenient and explicit. Moreover, a PHIL setup is built for testing a 400-Hz inverter to verify the effectiveness of the design method. Simulation and experimental results indicate that the setup achieves good performance. © 2017 IEEE.

关键词： Timing circuits

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Look-up table approaches for TCSC impedance control considering thyristor conduction characteristic

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The Journal of engineering 2018年第13期2017卷 1408-1412页

作者： Yi Yang Xiaojun Zhu Lei Gao Yubo Yuan Wei Yao State Grid Jiangsu Electric Power Research Institute Nanjing People's Republic of China Foshan Electric Power Company Foshan People's Republic of China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Hubei Sheng People's Republic of China

Thyristor-controlled series capacitor (TCSC) characteristic curves of fundamental frequency impedance change with line current considering thyristor conduction characteristic, which results in experimental deviation when using the open-loop impedance control. To end this, this study derives the TCSC fundamental frequency impedance mathematic model to reveal the theoretical mechanism that fundamental frequency impedance changes with line currents. This study proposes two new look-up table approaches to mitigate deviation of the least square look-up table approach using the three-point quadratic interpolation and linear interpolation algorithms. The proposed methods have been validated via TCSC physical simulation experiments.

关键词： thyristor applications least squares approximations interpolation linear interpolation algorithms three-point quadratic interpolation least square look-up table approach TCSC fundamental frequency impedance mathematic model thyristor-controlled series capacitor thyristor conduction characteristic TCSC impedance control look-up table approaches

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