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IEEE PES Asia-Pacific Power and Energy engineering Conference (APPEEC)

作者： Fengwei Tian Ming Li Xiangning Lin Pengyu Yang Peiwen Zheng State Key Laboratory of Advanced Electromagnetic Engineering Huazhong University of Science and Technology Wuhan China Electric Power Research Institute of China Southern Power Grid Guangzhou China

ISBN: (纸本)9781479975389

This paper makes a brief introduction to the protection logic of the last circuit breaker of arrester type. Afterwards, two novel protection strategies for the last circuit breaker of arrester type are proposed aiming at solving the problem that the protection of the arrester type last circuit breaker at the inverter side of the high-end converter cannot function properly when it's out of operation. Based on the simulation model of the ±800 kV Yunnan-Guangdong UHV AC-DC hybrid systems, a simulation verification is carried out on the PSCAD / EMTDC platform, and the result indicates the correctness of the proposed two novel protection strategies for the arrester type last circuit breaker.

关键词： Arresters Circuit breakers Integrated circuit modeling Inverters Voltage control Analytical models Leakage currents

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The establishment of wind farm dynamic Co-simulation platform and influence analysis of wind conditions

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Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2014年 29卷 356-364页

作者： Zhuo, Yixin Xu, Lüyang Lin, Xiangning State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan430074 China

With the development and utilization of wind power, wind turbine trip-off and damage accidents has occurred frequently because of the severe wind conditions, having adverse impacts on the stability and safety operation of power grid. Therefore, it is necessary to establish an appropriate model for wind farm operation analysis considering various wind conditions. Through combining on Digsilent and Matlab, this paper established a dynamic wind farm simulation platform with three parts of wind condition, wind turbine and fatigue respectively. Based on this platform, a variety of standard wind conditions with wake effects can be formulated, and their electric influence and fatigue damage on wind turbines can be analyzed in detail. The simulation platform is validated through a demo wind farm, and the influence of wind conditions is evaluated. ©, 2014, Diangong Jishu Xuebao/Transactions of China Electrotechnical Society. All right reserved.

关键词： Wind turbines

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Beam tail effect of a performance-enhanced EC-ITC RF gun

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中国物理C（英文版） 2013年第12期37卷 119-124页

作者： HU Tong-Ning PEI Yuan-Ji QIN Bin CHEN Qu-Shan State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan 430074 China National Synchrotron Radiation Laboratory University of Science and Technology of China Hefei 230029 China

The beam tail effect of multi-bunches will influence the electron beam performance in a high intensity thermionic RF gun. Beam dynamic calculations that illustrate the working states of single beam tail and multi-pulse feed-in of a performance-enhanced EC-ITC (external cathode independent tunable cavity) RF gun for an FEL (free electron laser) injector are performed to estimate the extracted bunch properties. By using both Parmela and homemade MATLAB codes, the effects of a single beam tail as well as interactions of multi-pulses are analyzed, where a ring-based electron algorithm is adopted to calculated RF fields and the space-charge field. Furthermore, the procedure of unexpected deviated-energy particles mixed with an effective bunch head is described by the MATLAB code as well. As a result, the performance-enhanced EC-ITC RF gun is proved to have the capability to extract continual stable bunches suitable for a high requirement THz-FEL.

关键词： EC-ITC thermionic RF gun beam tail effect multi-pulses FEL injector beam dynamics

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A novel inertial control strategy for full-capacity wind turbine with PLL by optimizing internal potential response

A novel inertial control strategy for full-capacity wind tur...

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International Conference on Electrical Machines and Systems (ICEMS)

作者： Shuai Li Jiabing Hu Shuo Wang Hongjie He Lin Wang Gang Liu State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Jiangsu Electric Power Company Nanjing China Xuji Corporation State Grid Corporation of China Xuchang China

ISBN: (纸本)9781479951635

This paper proposes a new inertial control strategy for full-capacity wind turbine (FCWT) synchronized with grid via phase locked loop (PLL) technique. It is worth noting that there is no need to measure the grid frequency and obtain the frequency differential as the fairly common practice does. The control strategy is essentially realized by optimizing the response characteristic of the internal potential, which is actually the rotating space vector of the FCWT's output voltage produced by the grid-side converter. In order to obtain the expected response characteristic of the internal potential, control bandwidths of both PLL and DC-link voltage loop are optimized. It is exactly based on that the FCWT can fast response and participate in stabilizing the grid frequency firstly relying on the stored energy in DC-link capacitor when disturbance occurs in grid. In the meantime, the variation of DC-link voltage during the response process is used to fine-tune the speed reference value to obtain the large kinetic energy in the mechanical system. Simulation model was built in MATLAB/Simulink and simulated results demonstrate the feasibility and correctness of the presented control strategy.

关键词： Phase locked loops Electric potential Voltage control Wind turbines Vectors Bandwidth Capacitors

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Transient overvoltage control for a wind farm based on goal representation adaptive dynamic programming

Transient overvoltage control for a wind farm based on goal ...

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International Conference on Power System technology (POWERCON)

作者： Yu Su Ju Liu Shiwu Liao Yu-fei Tang Jiakmi Fang Jinyu Wen Haibo He State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China University of Rhode Island Kingston RI USA Aalborg University Aalborg Denmark Huazhong University of Science and Technology Wuhan Hubei CN

With increasing intermittent and fluctuant wind power integrated into the power system, the high penetration of wind generation has brought a series of challenges including voltage stability for the safe operation of power system. Static VAR Compensator (SVC) has been widely used to control the voltage on the point of common coupling (PCC) of wind farm. When severe fault occurs and leads to serious voltage drop in the system, SVC controlled by the conventional control method may cause voltage overshoot after the fault clearance due to its response time lag. And this voltage overshoot of PCC may lead to the failure of high voltage ride through. In order to solve such a problem and improve the system voltage stability under severe fault conditions, a goal representation adaptive dynamic programming (GrADP) based SVC controller is proposed in this paper. The proposed control method can precisely control reactive output of SVC through its self-learning function to approximate the optimal control policy. Thus the voltage on the PCC is effectively controlled. An IEEE four-machine two-area system is used to verify the effectiveness of the proposed approach. Detailed simulation analysis and comparative studies with particle swarm optimization (PSO) optimized SVC controller are carried out to demonstrate the performance of the new method. Simulation results indicate that the proposed control strategy is effective in mitigating the voltage overshoot with good adaptability under various operating conditions.

关键词： Static VAr compensators Voltage control Voltage measurement Power system stability Wind farms Wind turbines Reactive power

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Participation of large-scale wind power generation in power system frequency regulation

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Chinese Science Bulletin 2013年第36期58卷 4557-4565页

作者： SUN HaiShun LIU Ju WEN JinYu CHENG ShiJie LUO Cheng YAO LiangZhong State Key Laboratory of Advanced Electromagnetic Engineering and Technology School of Electrical and Electronic EngineeringHuazhong University of Science and Technology Midwest Independent Transmission System Operator Inc. China Electric Power Research Institute

The initiative participation of wind power generators in power system frequency regulation is an inevitable demand to ensure power system safe operation with large-scale wind power ***,it is principally difficult for conventional wind turbines to participate in power system frequency *** this reason,solution to this problem is becoming a hot topic in the current *** paper systematically reviews the relevant research progresses in the control strategies and the capability assessment of using wind power generators in the power system frequency regulation,including the comparing among the emulating inertia control,the droop control,the rotor speed control,the pitch angle control and the coordinated ***,future research in this area is pointed out in the paper.

关键词：风力发电机电力系统频率调节控制策略风力涡轮机安全运行惯性控制转速控制

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Study on polarization and depolarization current detection device for XLPE cable

Study on polarization and depolarization current detection d...

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IEEE Symposium Power Modulator

作者： Gang Ye Hua Li Fuchang Lin Jin Tong Qin Zhang Xiaogang Wu Zeqi Huang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Humzhong University of Science and Technology Wuhan P. R. China Electrooic and Information School Yangtze University Jingzhou P. R. China

The polarization/depolarization current (PDC) detection device was designed to measure the broad range current from μA to pA level, which was suitable for 10kV XLPE cables ageing test. To achieve wide range of measurement, the ultra-low bias current amplifier and feedback resistances which had different values were used in the I/V conversion circuits. Teflon material was taken to prevent leakage current in the circuit board. Some effective methods (e.g. ultra-high value resistance, electromagnetic shielding, multiple filters, and high precision A/D conversion) were used to improve the accuracy and resolution of the measurement. The verification indicates that the device has a current measuring range of ±20μA, and a resolution of 0.1pA. The device was used to measure the PDC of the aged cable sample.

关键词： Current measurement Electrical resistance measurement Aging Resistance Cable insulation Switches

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Application analysis of large hydro-generator loss of excitation protection and its improvement

Application analysis of large hydro-generator loss of excita...

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International Conference on Power System technology (POWERCON)

作者： G. Q. Lu M. Long J. H. Li X. F. Tang J. Zou X. G. Yin Z. Zhang State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China Three Gorges Project Cascade Dispatching Communication Centre of China Yangtze Power Co. Ltd Yichang China

Concerned with loss of excitation (LOE) protection for large hydro-generators, several engineering issues with their improvement approaches are investigated. Based on the analysis of the variable excitation voltage criterion on its principle, performance and application, it's indicated that the expected function advantages of the criterion are actually not available, bringing about more potential failure in the rotor circuit instead. As a result, it's recommended LOE protection scheme for large hydro-generators should mainly consists of criteria on the stator side. The setting values of LOE protection and under excitation limit (UEL) control are calculated separately, resulting in the mismatch of each other easily, which impairs the generator's power supply support. Considering the steady state stability impedance criterion commonly used for large hydro-generator LOE protection as principal criterion, the paper presents an algorithm of comparing the operation zone of LOE protection and UEL control, followed by several schemes on their better cooperation.

关键词： Generators Stability criteria Power system stability Impedance Steady-state Stators

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Research of the soft start circuit for the high voltage power supply based on PSM technology

Research of the soft start circuit for the high voltage powe...

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2013 IEEE 25th Symposium on Fusion engineering, SOFE 2013

作者： Xia, L.L. Zhang, M. Ma, S.X. Yu, K.X. State Key Laboratory of Advanced Electromagnetic Engineering and Technology Wuhan China

ISBN: (纸本)9781479901715

The power supply based on pulse step modulation (PSM) technology has been widely used as the high voltage power supply for additional heating systems, such as RF H&CD and NBI in tokamaks. The topology contains numbers of converters and multi-secondary transformers. For the magnetic inrush of the transformer and the charge current of the converters connecting with the secondary windings of transformer, the power up of the power supply system is quite complex. PSM power supply starts up by two steps: the soft start of transformer and the pre-charge of the converters. Resistor branches series with the transformer and each converter are used to limit the inrush current. A lot of resister branches and parallel contactors in the converter modules are required, as a result the dissipation and electromagnetic interference (EMI) are serious. In this paper, the soft start circuit is simplified to only one step for decreasing the dissipation and EMI. The pre-charge circuits of the converters which are connected to the secondary at first are diverted to the primary winding of transformer can also limit the magnetic inrush current. Since the multi-secondary transformer powers up as the same time as converters, the capacitors in all converters will limit the ramp up rate of the transformer voltage, and the magnetic inrush current can be ignored. To analyze the characters of the precharge branches, all converters can be equaled as parallel during the soft start process. The equivalent circuit, a series RLC circuit, is proposed in this paper. A 1.2kV power supply, contains 12 converters, with soft-start has been built up in laboratory. Simulation and experiment results are shown to verify the theoretical analysis. A new soft start circuit of 100kV high voltage power supply system was designed. © 2013 IEEE.

关键词： Electric power systems

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A continuous sliding mode controller for the PMSM speed regulation based on disturbance observer

A continuous sliding mode controller for the PMSM speed regu...

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Annual Conference of Industrial Electronics Society

作者： Chaoxu Mu Wei Xu Xinghuo Yu Changyin Sun School of Automation Southeast University Nanjin China School of Electrical Engineering and Automation Tianjin University Tianjin China State Key Laboratory of Advanced Electromagnetic Engineering and Technology Huazhong University of Science and Technology Wuhan China School of Electrical and Computer Engineering Royal Melbourne Institute of Technology Melbourne Australia

This paper mainly studies the speed control for a permanent magnet synchronous motor system. The relationship between the reference quadrature axis current and the speed output is approximately considered as a second-order model. Based on this second-order model, a composite control strategy is adopted, where a continuous sliding mode controller is designed for the speed regulation without chattering and a disturbance observer is introduced as a compensator to resist disturbances and to reduce control gains. Simulation results have been presented to illustrate that the proposed method has good responses to reference speed signals with torque load disturbances.

关键词： Observers Angular velocity Stators Torque Educational institutions Sliding mode control Couplings

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