DOU Zhen-lan, WANG Han, LING Zhi-bin, CAI Xu

 (Wind Power Research Center & State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China)

Abstract: In the laboratory without the condition of actual wind farm or wind turbine, building an experiment platform of wind turbine output characteristic emulation is very important to the research of the wind energy generation system. The model of wind turbine torque is built by the blade element theory and the assignment of weight coefficient for blade element, considering the influence of vortex. The characteristic of the wind turbine is emulated by controlling the torque of DC motor according to the similarity between wind turbine and DC motor. And the experiment platform of variable speed constant frequency WEGS is built. The experiment not only confirmed the correctness and real time performance of the wind turbine model, and reflected the rapid tracking performance of the emulated torque according to the variable wind speed, but also verified the correctness of the control strategy of variable speed constant frequency WEGS, and provided the effective solutions for the WEGS research. 9 Refs. In Chinese.

Key words: wind turbine; wind turbine torque; modeling; blade element theory; weight coefficient assignment; DC motor; wind turbine emulator

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 1—5.

 

CHEN Liang-liang, YIN Hong-xu，ZHOU Bin，ZHANG Hao, DING Zhi-gang

(State Grid Electric Power Research Institute, Nanjing 210061, China)

Abstract: Series resonant DC/DC converter based on variable-frequency control has such advantages as simple topology structure, ZVS for switching MOSFETs in all input voltage and full load range, ZCS for output rectifier diodes and high efficiency, thus this converter is currently one of the research hotspots in switching power converters in the world. The principle of series resonant DC/DC converter is analyzed firstly, and the converter’s characteristics under three kinds of working frequencies are also described in this paper, and the relationship between such parameters as input voltage, output voltage, switching frequency and resonant inductor of this converter under different conditions is also quantitatively provided. Experimental results on a 1.5KW prototype verified that a 96.3% conversion efficiency can be achieved, all switching MOSFETs realized ZVS, and the relationship between such parameters as input voltage and output voltage is consistent with theoretical analysis. In addition, the experimental waveforms are also consistent with simulation waveforms in this paper. 7 Refs. In Chinese.

Key words: variable-frequency control; series resonant; DC/DC converter; ZVS

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 6—9.

 

SU Yu-xiang, LIU Guo-ping, SHEN Xiao-qun, YE Ji-ying

(Mechanical and Electrical Engineering Institute, Zhejiang Ocean University, Zhoushan 316000, China)

Abstract: Improved Hilbert-Huang Transform (HHT) is introduced for detection and analysis of power quality in marine power system for the first time in this paper. Mode mixing is happened when using EMD directly for harmonic analysis, and all harmonic components cannot be effectively separated. The HHT method based on Fourier transform is used to solve the problem in this paper. Firstly, signal is filtered according to Fourier spectral. Then, the output of signal after band filter is decomposed by EMD, and accurate IMF components are obtained. Lastly, Hilbert transform is used for the IMF components, and amplitude and frequency of corresponding time can be detected accurately and quantitatively. The HHT method based on Fourier transform can separately detect harmonic components and obtain the time-amplitude and time-frequency of harmonics. Simulation results show that this method has better performance in analyzing Harmonics to Wavelet packet in marine power system. 17 Refs. In Chinese.

Key words: Hilbert-Huang transform; Fourier transform; marine power system; harmonics

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 10—14.

 

BAO Guang-hai, ZHANG Pei-ming

(College of Electrical Engineering & Automation, Fuzhou University, Fuzhou 350108, China）

Abstract: ANSYS software is used to simulate the dynamic characteristics of flat surface AC contactor and the dynamic characteristics is tested by high-speed cameras to verify the correctness of the simulation results. The magnetic force characteristics of inclined surface AC contactor in different angles are calculated and the static characteristics with the flat surface AC contactor are compared. Finally, artificial fish swarm optimization algorithm is used based on genetic algorithm to optimize the design of the dynamic characteristics of inclined surface AC contactor. The optimization results show that the coil and core volume of inclined surface decrease greatly than that of the flat surface, and its dynamic characteristics is better than flat surface AC contactor.

Key words: AC contactor; inclined surface; dynamic characteristics; genetic algorithm; AFSA;

optimization design

 

ZHANG Min, CAI Chuang-wen, LIU Wei, ZHOU Shao-wu

(School of Information and Elec. Eng., Hunan University of Science and Technology, Xiangtan 411201, China)

Abstract: A class of hybrid uncertain system is put forward in respect to nonlinearity and uncertainty of power systems with SVG (static VAR generator). The design method of robust H∞ controller for the system is given and applied to multi-machine power system with SVG. The controller for SVG and excitation of generators is designed. The simulation results verify effectiveness of the controller. 14 Refs. In Chinese.

Key words: multi-machine system; SVG, robust H∞ control; direct feedback linearization; Ricatti equation

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 19—23.

 

SUN Jing-feng，YANG Qing-xin，ZHANG Chuang，LI Yong-jian

(The Province-Ministry Joint Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability,

Hebei University of Technology, Tianjin 300130, China)

Abstract: Under alternating or rotating magnetic excitation, a magnetic material’s reluctivity becomes a full three-dimensional tensor. In some applications, this tensor is simplified as a scalar or a vector, and the result is accurate enough. However, the consideration of the off-diagonal terms in a reluctivity tensor is necessary when high calculation accuracy is demanded. In this paper, a finite element formulation is developed from Maxwell’s equations and 6-node triangular prism element shape function. In the formulation the off-diagonal terms of reluctivity tensor are fully considered. Based on this formulation, a finite element analysis program is compiled, using Femap to create a model and to display the magnetic flux distribution. Several simulations of a current-carrying air-core square coil between two iron plates are performed based on different reluctivity tensor. The results are compared and it could be found that different forms of reluctivity tensor will lead to different distributions of magnetic flux and each off-diagonal term of reluctivity tensor play a unique role.

Key words：reluctivity tensor, three-dimensional magnetic field, finite element analysis

 

LI Man-hua¹, LU Hua-cai², SUN Si-zhou²

(1. Modern Education Center of Anhui Polytechnic University, Wuhu 241000, China;

2. College of Electrical Engineering of Anhui Polytechnic University, Wuhu 241000, China)

Abstract: In view of the large model uncertainties and disturbances of permanent magnet synchronous linear motor (PMSLM) feeding system for high-speed NC machine tool, a SISO frequency domain model for the feeding system is set up firstly, then a robust PID controller is designed using H∞ closed-loop gain shaping control techniques. Simulations and experiments show that the tracking error and the speeding response of the designed robust controller is much superior to those of the traditional PI controller, the designed nonlinear controller is robust to model uncertainties and disturbances, and has strong robustness to model uncertainties and external disturbance.

Key words: permanent magnet linear motor; feeding system; robust control

 

HUANG Yu-qi¹，DONG Qin¹，ZHU Jia-hui²

(1. Fuzhou Power Supply Bureau, Fuzhou 350009, China；

2. China Electric Power Research Institute, Beijing 100192, China)

Abstract: Due to the disadvantages of poor electrical characteristics and poor maintainability, the energy storage battery could not meet the demand of the intelligent microgrid in the future. The flywheel and diesel generators combined energy storage system is proposed to be applied in the microgrid. The flywheel, owing to the ability of high power and unlimited full power cycle, is used to stabilize the power fluctuations of micro sources and the load. Diesel generators, which are low cost, can provide uninterrupted backup power supply. When the fault occurs in the grid, the power shortage in the microgrid is temporarily provided by the flywheel and the most of the load is normally working waiting for the reclosing of the main grid. If the fault is permanent, the electrical controller starts diesel generators. Theoretical analysis and simulation show that the flywheel and diesel generators combined energy storage system applied in the microgrid is feasible and efficient, and can improve the anti-accident ability of the microgrid. 21 Refs. In Chinese.

Key words: micro-grid; flywheel energy storage system; diesel generator; anti-accident; power supply reliability

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 32—37.

 

HAO Zheng-hang^1,2, CHEN Zhuo²

( 1. College of Electrical and Automation Engineering, Tianjin University, Tianjin 300072, China;

2. College of Electrical Engineering, Guizhou University, Guiyang 550003, China)

Abstract: Based on the small signal stability region defined on power injection space, a calculation method of applied boundary for multi-power systems is presented. Firstly, in the two-machine power system, the characteristic of the small signal stability region is studied, and it is found that its boundary has a regular shape in the 2-dimension plane. Secondly, using the technology of groups division and system equivalent of two-machine, the search of Hopf bifurcation set in multi-machines systems is implemented. In the paper, it is showed that all the Hopf bifurcation set based on the subspace of equivalent of two-machine can be mapped with the Hopf bifurcation set of the original systems. Therefore, the Hopf bifurcation set of equivalent simplification system can be regarded as an applied small signal stability boundary of the original power systems. Finally, through calculating the original boundary and the applied boundary for a four-machine power systems, it is proved that the applied boundary approximates to the original boundary.

Key words: power system; small signal stability region; Hopf bifurcation; applied boundary

 

WANG Jie, ZHANG Xiao-qing, WANG Tao, CHEN Hao, SHENG Cai-wang, LIU Feng

(School of Electrical Engineering, Beijing Jiao Tong University, Beijing 100044, China)

Abstract: This paper is mainly aimed at discussing the calculation method of human-earth induced voltage which is generated by AC high-voltage overhead power lines, as well as touch-current of human body. At the beginning of this paper, the human body is simply equivalent to a cylinder, and the calculation model of human-earth induced voltage generated by single phase high-voltage overhead power line is derived by Equivalent Charge Method. On basis of it, this model and calculation method are further extended to the three-phase high-voltage overhead power lines situation. Secondly, this paper applies the derived model and calculation method to calculate the current through the human body when the human body touches the conductor under overhead power lines. It has the advantages of simple calculation procedure, small calculation burden, and convenient to engineering application. 9 Refs. In Chinese.

Key word: high-voltage overhead power lines; power-frequency electric fields; equivalent charge method; induced voltage; touch-current

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 43—46.

 

YANG Dong, SHEN Zhi, LIU Zhen-xiang, YANG Li-jia, JIANG Ya-qin, OUYANG Jian-ming

（National University of Defense Technology, Changsha 410073, China）

Abstract: The radial magnetic field distribution of the helical coil electromagnetic launcher’s driving coil is investigated by numerical simulation, from which a “D” shaped cross section armature is proposed and its best location is determined. The results show that, with the same size, the acceleration of the “D” shaped armature is bigger than the rectangular armature, i.e., with the same length of the launcher, the muzzle velocity of the “D” shaped armature is bigger than the rectangular armature. Taking the “D” shaped armature as an example, the axial and radial force distribution of the armature coil and the driving coil is investigated. The results show that the radial forces on the armature coil and the driving coil are mainly swelling forces, and the structure surround the coils should be reinforced in the launcher design.

Key words: electromagnetic launching; coilgun; HCEL; radial force

 

ZHAO Quan-bin, FU Qi, HE Jun-ping

(Shenzhen graduate School, Harbin Institute of Technology, Shenzhen 518055, China)

Abstract: Electromagnetic radiation emission from a switched mode power supply is easily exceeding EMC standard limits and this phenomenon is difficult to debug for many switched mode power supply designers. It is very necessary to study electromagnetic radiation mechanism, characteristics and prediction method for industrial community and academia. After analyzing and modeling of some active and reactive components, such as capacitor, transformer, diode, MOSFET, PCB traces, input/output cords, a FDTD model of a flyback SMPS is set up. The distribution pattern and magnitude characteristics of far-field electromagnetic radiation are simulated and analyzed based on X-FDTD software. Using simulation tool, it is found that input and output cables have a significant influence on the far-field electromagnetic radiation distribution of the flyback power supply in 30MHz-300MHz. The capability of a common mode EMI choke to inhibit radiation is verified by using simulation. This paper is useful for SMPS engineers to design and decrease far-field electromagnetic radiation. 10 Refs. In Chinese.

Key words：Flyback power supply; electromagnetic radiation; FDTD; simulation prediction

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 51—54.

 

ZHAO Hui, LI Bin, YUE You-jun

(Tianjin Key Laboratory for Control Theory & Applications in Complicated System

(Tianjin University of Technology), Tianjin 300384, China)

Abstract: Wind power has the characteristics of random and intermittent, so wind turbine output power varies widely. Wind turbines may therefore cause the output power fluctuations and lead to voltage fluctuations, which may cause flicker problems. Based on the features of wind power and characteristics of wind power generators, a mathematical model had been built in this paper and the auto-disturbance rejection control (ADRC) was introduced to the wind turbine control system. The torque spikes signal was treated as uncertain disturbances in the system. ADRC controller was used to estimate and compensated disturbances signal, nonlinear state error feedback (NLSEF) inhibit the fluctuations of rotor current, and suppress torque disturbance. The simulation results show that the new controller ensures very good robustness. In the generator output side, it can effectively restrain the disturbance signal. The improved static and dynamic performance of wind turbine will help to enhance the quality of power supply.

Key words: doubly-fed wind generator; voltage fluctuation and flicker; active disturbance rejection control; MATLAB simulation

 

QI Jun-jian¹, HE Guang-yu¹, MEI Sheng-wei¹, GU Zhi-dong²

(1. State Key Lab of Power Systems, Dept. of Elec. Eng., Tsinghua University, Beijing 100084, China;

2. Power Dispatch and Communication Center, Hainan Electric Power Company, Haikou 570203, China)

Abstract: State estimation is an important part of the energy management system of the power system. As the weighted least squares estimation does not have robustness, robust estimation theory was proposed. This paper introduces the definition, goals, and types of the robust estimation and reviews both classical and newly emerging power system robust state estimation methods. The classical methods mainly include M estimation, GM estimation, and high break-down point estimation. The new methods mainly include innovation graph state estimation, maximum correntropy estimation, minimum information loss state estimation, maximum agreement estimation, maximum constraints satisfaction estimation, maximum good measurement rate state estimation, and maximum normal measurement rate state estimation. The new methods improve the robustness of state estimation by adding useful information and thus promote the development of the study on power system state estimation.Various methods are compared and the advantages and disadvantages of these methods are analyzed. At the end of this paper the prospect of this research area is envisioned. 46 Refs. In Chinese.

Key words: power system; state estimation; robust state estimation

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 59—64.

 

ZHOU Kai¹, WU Ying-xia², TAO San-tao¹, ZHAO Wei¹, LI Xu-tao¹

(1. School of Elec. Eng. and Information, Sichuan University, Chengdu 610065; China;

2. Chongqing Electric Power Dispatch Center, Chongqing 400014, China)

Abstract: Medium voltage cable terminations are widely used for flexible AC transmission (FACTS) and connecting terminations for electric motors driven by inverters. These cable terminations are possibly subjected to high electrical stress because of high frequency voltage components. In this paper, an experimental setup was designed to test cable terminations insulation under high frequency sinusoidal voltage. A signal generator and a power amplifier were used to generate high frequency voltage and larger output power. The voltage was used for the input of high frequency transformer in order to generate high voltage. Also, work frequency high voltage was generated by work frequency transformer. The two kinds of voltages were both applied to specimens at the same time. As a result, a superposition waveform by high frequency and work frequency waveform was formed. Two filters composed of LC components were also needed. Furthermore, to simulate working condition, a current transformer is used to obtain 150A current. Through the analysis of experiment and thermal images, the experimental setup has positive effect on investigating insulation characteristics of cable termination.

Key words: medium voltage cable; insulation of termination; high frequency voltage; large current

 

QIU Qiu-fei^1,2，ZHU Wei³，ZHAO Yun-fei¹,WU Ye-qing¹

(1. Institute of Science and Technology Information of Zhejiang Province, Hangzhou 310006, China; 2.WANXIANG EV CO., Ltd, Hangzhou 311215, China; 3. Zhejiang Public Information Co., Ltd, Hangzhou 310005, China)

Abstract: Regenerative braking is not only a significant characteristic of EV, but also can improve its economic efficiency. The constraints are analyzed in the course of braking energy recovery. Then by designing the vehicle structure and the control strategy of regenerative braking system to resolve or weaken the problem that limits the braking energy recovery, meeting the design’s objective. At last, the test is done on the road, and the result indicates: 25% power can be recovered, and the mileage is prolonged. 8 Refs. In Chinese.

Key words: regenerative braking；SP-HEV；control strategy；drive

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 70—74.

 

NIE Hong-zhan, WANG Bi-yuan

 (School of Electrical Engineering, Northeast Dianli University, Jilin 132012, China)

Abstract: The traditional transmission network planning is confined to a single-level construction, while the actual transmission network planning needs to take into account the time factor, namely how to build the best route to network planning. The difficulty of the multi-stage planning is the transition between stages, with the later stages of the decision-making depending on earlier stages of decision-making. Classic dynamic programming can not solve large-scale transmission network planning program. In this paper, pseudo-dynamic programming deals with the multi-stage problem, whose objective is to reduce the number of iterations. The combination of Chaotic Optimization Algorithm and Artificial Fish School Algorithm is free from blindness and limitations of the hybrid algorithm search. The hybrid algorithm is efficient and quick in computation. The calculation results of the 46-bus system reveal that applying hybrid algorithm into transmission network planning is not only feasible, but also has a very high computational efficiency.

Key words: multi-stage planning; transmission network expansion planning; dynamic programming; chaos optimization algorithm; artificial fish school algorithm

 

TENG Zhi-jun, QU Yin-long, WANG Zhong-bao, YANG Xu

（Dept. of Information Engineering, Northeast Dianli University, Jilin 132012, China）

Abstract：In modern power system, the temperature monitoring of high-voltage live parts has become one of practical problems in the safe operation of electrical equipment. This paper proposes a high-voltage live parts temperature measurement that includes ZigBee wireless sensor networks as the core, Ethernet as the backbone and CC2430 chip as the sensor control core. ZigBee network of the system runs on 2.4GHz free frequency band. When tree topology is used to build system network, the maximum root depth is 5. The network can monitor the high-voltage live parts within 150m radius circular area in real time. The system network is scalable and can support up to 65,535 nodes. The system temperature monitoring range is -55 ℃ ~ +125 with 14 bits resolution. When the range of monitoring temperature is -10℃~+85℃, accuracy can be achieved within ±0.5℃.Through the experiment, the real-time temperature monitoring system of high-voltage live parts not only is stable and reliable but also has high availability and market value. 6 Refs. In Chinese.

Key words: ZigBee; temperature; high-voltage live parts; monitor

// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(3). 80—83.

 

XIA Xiang-yang^1,3, GONG Fen^1,3, ZENG Xiao-yong¹, LUO Shi-wu², XU Lin-ju^1,3

(1.Changsha University of Science and Technology, Changsha 410077, China; 2. Chongqing Power Company Education and Training Center, Chongqing 400053, China; 3. Key Laboratory for Power Technology of Renewable Energy Sources, Hunan Province, Changsha University of Science and Technology, Changsha 410077, China)

Abstract: Considering the characteristics of the randomness and relevance of harmonics currents injected by the non-linear load in each node, in order to ensure the harmonic ratio of voltage and distortion to meet the threshold requirement to a certain level, a method to configure the filter device is put forward, which is based on improved simulated annealing - particle swarm optimization algorithm. The introduction of an adaptive algorithm inertia factor and memory in this optimization algorithm can ensure a good accuracy when the search greatly accelerate s the convergence speed. Simulation results show that the filter device configuration scheme by the algorithm can optimize the installation location and the corresponding parameters of passive filter and active power filter in distribution network, reduce the system losses, keep the voltage, power factor within a prescribed extent, make the system energy cost and the investment cost of filtering devices minimized, achieve a better filtering result and economic benefits, with certain value in engineering applications.

Key words: distribution system; simulated annealing –particle swarm optimization; harmonics; filter device