Promoting power generation from large-scale non-hydro renewable energy resources at right direction and firming confidence
YAN Lu-guang
(Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: On the basis of needs to the energy sustainable development system during the first half of 21 century and present development status of power generation from non-hydro renewable energy resources, the magnificent prospect and faced difficulties and problems were analyzed in the paper. Some related cognizances, opinions and suggestions for development of wind power, photovoltaic power, solar thermal power and establishment of integrated energy base in future were advanced. 11 Refs. In Chinese.
Key words: non-hydro renewable energy; wind power; photovoltaic power; solar thermal power
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 1—6.

Vacuum flashover developing across alumina ceramic at pulsed voltage
YU Kai-kun, ZHANG Guan-jun, ZHENG Nan, TIAN Jie, LIU Guo-qing
(State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Flashover phenomenon in vacuum has been an interesting issue in the fields of both electrical and electronic systems for more than half a century. However, this phenomenon is so complicated that up to now the related mechanisms have still not been understood clearly. In this paper the ICCD system was used to grasp the dynamic flashover images across the surface of alumina ceramic in vacuum under pulsed voltage excitation. The oscilloscope waveform shows that the peak value of current and lighting appear simultaneity with a little delay to the voltage truncation time .The results indicated that the flashover develops rapidly in less than 50ns and the electrode edge shows the highest light intensity. The ICCD images show that, before flashover phenomenon appears the lighting channel already occurs on the sample surface, the strongest lighting appears in about tens of nanosecond after flashover phenomenon occurs. While the current reaches its largest value, the strongest lighting intensity appears at the electrode edge. After metal film electrode sputtered on the sample the flashover voltage decreases, the lighting intensity increases, and there is recombination process between electrodes in the material. 16 Refs. In Chinese.
Key words: vacuum; alumina ceramic; surface flashover; ICCD
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 7—11.

Electrical stimulation of nervous system by magnetic induction
ZHANG Guang-hao^1,2, JIANG Ling-tong^1,2, WU Chang-zhe¹, HUO Xiao-lin¹, SONG Tao¹
(1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
2. Graduate University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract: Implantable electrical stimulator is too large for people to move conveniently, whereas magnetic stimulation is not suit for deep nerve stimulation. This paper proposes a new method of electrical stimulation by magnetic induction. A small induction coil, which is connected with nerve stimulating electrodes, is first implanted. When stimulation is applied, a coaxial coil, in which pulsed current flows, is put outside the body. Thus, electrical field, which makes the nerve excited, is formed due to the generation of inductive electromotive force in the induction coil. Through theoretical analysis, finite element simulation and experiment, this paper compares the electric field produced by magnetic stimulation before and after implanting induction coil. Results show that the electric field on the nerve is apparently improved after implanting induction coil. 13 Refs. In Chinese.
Key words: magnetic induction; electrical stimulation; magnetic stimulation
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 12—15.

Experimental research on damage of dielectric materials under high power microwave in vacuum
HAO Xi-wei¹, ZHANG Guan-jun¹, QIU Shi^2,3, HOU Qing ³, HUANG Wen-hua³
(1.State Key Lab of Elec. Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an, 710049, China;
2. School of Electronic Engineering, Xidian University, Xi’an, 710071, China;
3. Northwest Institute of Nuclear Technology, Xi’an 710024, China)
Abstract: Breakdown of dielectric window materials limits the generation and transmission of high power microwave (HPM), which blocks the development of microwave technology. In order to study the physical mechanism of this phenomena, the dielectric breakdown experiments with several kinds of dielectric window materials, i.e., PTFE, LDPE, HDPE and PMMA, are performed under HPM with the power level of 1GW at 9.4 GHz in vacuum, and the model of microwave is TE11. The HPM breakdown characteristics of different materials are obtained, and the influence of different surface treatments for PTFE with notching and polishing on its breakdown characteristics is also studied. Based on the photography analysis of destroyed dielectric samples, it is found that, the breakage phenomena significantly occurred on the face of dielectric window along the direction of microwave electric field, and the damage status is greatly affected by the different surface treatments. By studying the samples with different damage, the development of dielectric breakdown under HPM is proposed, it is considered that the earlier damages present small circular aperture on the surface of material, then develop into perfoliate channels on the surface, and as the further breakdown occurs, the tree-like breakages develop from the surface into the inside of a material. 12 Refs. In Chinese.
Key words: dielectric window; HPM; breakdown; photography analysis
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 16—19.

Numerical simulation of arc plasma temperature based on ANSYS
HU Hui¹, YANG Qi¹, BAO Bin¹, HE Junjia², LI Jin²
(1.College of Environmental Science and Eng., Huazhong University of Science and Technology, Wuhan 430074, China; 2.College of Elec. & Electronic Eng., Huazhong University of Science and Technology, Wuhan 430074, China)
Abstract: Inhaled NO has good curative effect, non-traumatic and high selectivity, and is gradually widely used in clinical treatment of neonatal with acute lung injury and persistent pulmonary hypertension. Arc discharge is a new method of producing NO. So research on control of plasma parameters is of great significance in the clinical application of NO generated by arc discharge. Based on the theory of magnetic fluid dynamics, this paper established an axial symmetry mathematical model of pulsed arc plasma, and simulated the plasma temperature distribution and current density of arc-discharge by using ANSYS. The results show that, when the current increases, temperature near the anode and anode current density increase; when the arc length increases, temperature near the anode and anode current density increase, and cathode current density decreases slightly. The increase on temperature is beneficial to the formation of NO but goes against the generation of NO2.
Key words: arc discharge; plasma; temperature; simulation
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 20—23.

Pulse shortening phenomena in RBWO filled with neutral gas
GE Xing-jun, QIAN Bao-liang, ZHONG Hui-huang, LIU Jin-liang, XU Qi-fu, ZHANG Jun
(College of Opto-electric Science and Eng., National University of Defense Technology, Changsha 410073, China)
Abstract: Pulse shortening is a common phenomenon in high-power microwave tubes, which hinders the improvement of microwave output energy. So far, it is also an unresolved problem in the field of high-power microwave devices. In this paper, a gigawatt compact relativistic backward wave oscillator (RBWO) with coaxial extractor is investigated using the KARAT 2.5 D particle simulation code. Detail physical interaction pictures and the pulse shortening phenomena of the oscillator filled with neutral gas are presented. Typical simulation results reveal the production process of the plasma due to the collision of the relativistic electron beam with the neutral gas injected previously into the BWO tube and verify that the collision-produced plasma may efficiently neutralize the space-charge effect of the relativistic electron beam and enhance the production rate of the high power microwave. The simulation results show that, with over-high density plasma, there would be serious pulse shortening of microwave pulses, even the device can not work normally. Therefore, in order to improve the performance of RBWO, a suitable plasma density should be selected. 17 Refs. In Chinese.
Key words: pulse shortening; plasma; filled with neutral gas; RBWO; collision-ionization
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 24—28.

Study on properties of electrohydrodynamic (EHD) plasma actuator
LIU Yong, LI Qing-quan
(School of Electrical Engineering, Shandong University, Jinan250061, China)
Abstract: The atmospheric plasma generated by electrohydrodynamic (EHD) plasma actuator could convert electric energy into the kinetic energy of the surrounding gas and propel the layer flow to accelerate as a result. However, the physical explanation of this process has not been given yet and the problem of surface tracking has limited the further improvement of plasma actuator’s performance. In this paper, the electrical and electrohydrodynamic properties of symmetric plasma actuator in air and nitrogen are measured and the energy transfer process is analysed. Experiment results show that symmetric plasma actuator could work in “Push” mode and the negative ions appear to play a positive role in the energy transfer process. Furthermore, we found out that sealing the plasma actuators proves to be considerably effective in suppressing surface tracking and lay firm foundation for the future application of EHD plasma actuator. 12 Refs. In Chinese.
Key words: electrohydrodynamic; plasma actuator; energy transfer; surface tracking
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 29—32.

Influence of surface roughness on flashover characteristics of insulating materials in vacuum
ZHENG Nan, YU Kai-kun, LIU Guo-qing, ZHANG Guan-jun
(School of Elec. Eng., State Key Lab of Elec. Insulation & Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Under the high electric field, discharge sometimes occurs along the surface of solid in vacuum, gas or liquid dielectrics, and it is called the surface flashover. The voltage of discharge is known as flashover voltage. When surface flashover occurs, the voltage is usually far below the breakdown voltage of the solid itself or the atmosphere, especially in vacuum. The surface flashover phenomena across insulating materials always lead to the failure of system insulation and may cause serious accidents. The flashover along the surface of the insulating material is interesting to many researchers. The flashover phenomena along PTFE and machinable ceramics are investigated under impulse voltage in vacuum. This paper finds that changing the surface roughness of the insulating materials has obvious influence on their flashover characteristics. These phenomena can be reasonably explained.
Key words: impulse voltage; surface flashover; insulator; charge transport; secondary electron emission
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 33—36.

Application of computer graphics to detection of transformer winding deformation with FR data
XU Yuan, LIU You-wei, BI Jian-gang
(High Voltage Department, China Electric Power Research Institute, Beijing 100192, China)
Abstract: To improve the effect in detection of the transformer winding deformation with FRA, based on the feature of FRA, mathematical morphology is used. The FR data are expressed with image. The key block is got after treatment with mathematical morphology method. Frequency band and morphology parameters of key block are defined. The difference between FR data can be expressed by them. The criterion of the method is given. The state of the transformer winding can be detected using the numbers and the morphology parameters of the key block. An example is given in the paper. For testing the effect of the method, the correlation coefficient method is compared with some cases. The method provides a new way to analyze the transformer winding deformation with FRA.
Key words: transformer winding deformation; FRA; mathematical morphology; key block
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 37—40.

A novel control strategy for the PWM rectifier in cascaded multilevel converter
WANG Jian, LI Yong-dong
(Tsinghua University, Beijing 100084, China)
Abstract: In power cells of the four-quadrant cascaded multilevel converters, the output power of H-bridge inverters is pulsating, which influences the control of the PWM rectifier, especially on the DC-link voltage. A novel control strategy for the PWM rectifier is proposed in this paper. The outer loop controller is made up of the CD-link feedback controller and the load power feedforward controller. The inner loop current controller is a proportional-integral-resonant (PIR) regulator. Experimental results show that the CD-link voltage is well-controlled even with a very small CD-link capacitor, which confirms the effectiveness of proposed control strategy. 13 Refs. In Chinese.
Key words: cascaded multilevel converter; PWM rectifier; load power feedforward; PIR regulator
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 41—45.

Study of array integration inductance in four-phase voltage regulator module
CHEN Chao, LI Hong-zhu，Fu Xing-wu
(Dept. of Electrical and Control Engineering, Liaoning Technical University, Huludao 125105, China)
Abstract: In order to increase the dynamic response performance and decrease the steady current ripple of VRM, an array magnetic core structure was formed by multiple separation magnetic core’s combination. Making use of the array magnetic core an array integration inductance is put forwarded which is applied to the four-phase VRM. Without considering the effect of leakage magnetic flux, the effect of the array integration inductance’s parameters for VRM’s performance is analyzed, and the equivalent circuit of the array integration inductance is established. Based on the equivalent circuit and making use of circuit simulation software, the performance of four-phase array integration inductance VRM is analyzed. At the same time, making use of circuit simulation software the performances between the four-phase array integration inductance VRM and the four-phase discrete inductance VRM are compared. The simulation results showed the correctness of the analysis. And the experimental results showed that the array integration inductance VRM has predominance dynamic response performance. 4 Refs. In Chinese.
Key words: voltage regulator module; array integration inductance; ripple current; equivalent inductance; dynamic response
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 46—49.

Augmented rail gun inductance gradient and its affecting factors
LIU Shou-bao, RUAN Jiang-jun, ZHANG Ya-dong, SU Yi
(School of Electrical Engineering, Wuhan University, Wuhan 430072, China)
Abstract: Inductance gradient directly relates to the magnetic force applied on armature and has great influence on the performance of a rail gun. Comparing with analytic method and experimental measurement method, numerical method has great advantage in obtaining inductance gradient. In order to realize the numerical computation of inductance gradient of augmented rail gun, this paper deduced the armature’s force formulation, illustrated the inductance gradient’s physical meaning, explained the simplified treatment of real model in simulation, built a rail gun’s 2D finite element method and a typical structure augmented rail gun’s inductance gradient was calculated accurately. The influence of loading current’s frequency and outer rail’s dimensions on inductance gradient were discussed; distribution of eddy current field in rail and spatial magnetic lines of force under varied influencing factors and outer rail dimensions was displayed and the cause of change in inductance gradient was explained. According to the analysis results, optimal design of augmented rail gun is suggested.
Key words: augmented rail gun; inductance gradient; virtual work principle; finite element; skin effect; eddy current
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 50—53.

Effect of impulse voltage on the turn to turn insulation of motor
HAN Dong¹, FU Xiang-bo¹, SONG Dun-fang²
（1. Chengdu Electric Power Bureau, Chengdu 610021, China;
2. Sichuan Electric Power Corporation, Chengdu 610021, China）
Abstract: Stator insulation of inverter-fed motors is experiencing continuous impulses with significant harmonics and transients. There are many differences in insulation aging mechanism between under continuous impulses and sine waves. The effects of the overvoltage due to switching, rate of rise and switching frequencies on the performance of insulation are not clear. In the work presented here, the effects of some critical factors which characterize the power inverters (voltage, frequency, rate of rise, duty cycle, etc.) are investigated to help to understand the failure mechanism of wire insulations under such conditions. The mechanism of insulation failure under these conditions can be either localized pinhole-type or massive destruction depending on the voltage and frequency applied. The fast rate of rise combined with high repetitive frequency accelerates wire insulation degradation.
Key words: impulse voltage; inter-turn insulation; aging
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 54—57.

Study on DC-link voltage rise in injection shunt hybrid active power filter 
LEI Zhen, LUO An, ZHAO Wei
(College of Electrical and Information Engineering, Hunan University, Changsha 410082, China)
Abstract: A novel high capacity hybrid power filter based on injection circuit is analyzed which can also compensate reactive power. The novel APF suits high power system for the fundamental resonance in the injection circuit. Considering the rise of DC-link voltage may influence the performance of the whole system greatly, this paper discusses the reasons of the rise on DC-link voltage and analyses the dynamic process of the voltage rise particularly. Based on the above analysis, some methods are put forward to restrain the rise of DC-link voltage, such as reducing dead time, the use of hysteretic control method, fore-feed control of reflowing current or direct control on DC-link voltage without a rectifier to supply. Application results have shown the validity of the proposed methods.
Key words: active power filter; rise of dc-link voltage; hysteresis comparison; PWM rectification
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 58—62.

A rotor position detection method for sensorless brushless DC motors used in electric bicycles 
YANG Xu, QU Wen-long
(State Key Lab of Power Systems, Dept. of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: A novel rotor position detection method was presented in this paper for sensorless brushless DC motor used in electric bicycles drive. In high speed, the back electromotive force zero-crossing point can be directly extracted by detecting the voltage difference between the virtual mid point and the mid point in the DC link. In low speed, the true back electromotive force zero-crossing point can be extracted by detecting the voltage difference between the virtual mid point and the low point of the DC link. The commutation signal can be obtained by delaying the back EMF zero-crossing point 30o electric degrees. This method can extend motor’s speed range. The proposed method is not sensitive to switching noise, so no filtering is required. The principle of the detection method is described in detail, and some experimental results are shown to verify the feasibility of the method.
Key words: sensorless brushless DC motor；virtual mid point voltage；back EMF zero-crossing detection
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 63—67.

Study of AC-DC-AC matrix converter based on AC chopper inverter
YUE Zhou, ZHU Jian-lin, YANG Ling
（1. Dept. of Communication and Eng., Hunan University of Humanities and Science & Technology, Loudi 417001, China; 2.College of Information Eng., Xiangtan University, Xiangtan 411105, China）
Abstract: Three types of new AC-DC-AC matrix converter topology based on matrix converter and AC chopper inverter are proposed, which are referred as AC chopper matrix converters. First, the basic configuration of these new topologies and the fundamental principle are introduced. Then, the validity and feasibility of the new topologies are tested by digital simulation and prototype experiments. The results indicate that the output voltage transfer ratio can be larger than 1.0, the output voltage waveform is very close to standard sine wave, and the harmonic contents increase slightly, overcoming the drawbacks of conventional MCs that maximum voltage transfer ratio is 0.866. This study may provide inspiration for further engineering applications.
Key words: AC chopper inverter; matrix converter; voltage transfer ratio; simulation; prototype
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 68—72.

Operation ticket expert system based on on-line network topology analysis 
LI Ling, LUO An, ZHAO Wei
(College of Electrical and Information Engineering, Hunan University, Changsha 410082, China)
Abstract: An operation ticket expert system based on on-line network topology analysis is proposed in this paper. In the system, a production method and a tree-net method are used to express expert knowledge database, and adjacency list is used to describe network topology relations. The components needed to operate are obtained via Hash arithmetic and on-line SCACD real time data. Then the actual operation lists are gained after the forward reasoning. The application results indicate that the system is feasible, intelligent and reliable.
Key words: operation ticket; expert system; tree-net; network topology; adjacency list; Hash arithmetic
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 73—77.

Progress of Journal ‘Advanced Technology of Electrical Engineering and Energy’
QIN Jie, LIN Liang-zhen, QI Zhi-ping, MA Yu-huan, SHEN Guo-liao, JING Bo-hong
(Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: The paper has introduced the Journal ‘Advanced Technology of Electrical Engineering and Energy’, presented its main journal evaluation indexes. The result indicates that the journal has made great progress in recent years. It gives much info. about the journal to authors. 13 Refs. In English.
Key words: journal ‘Advanced Technology of Electrical Engineering and Energy’; progress; journal evaluation index
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(2). 78—80.