|
A novel phase-shifted and overlapping three-level inverter with high power and high frequency output
ZHENG Ying-nan, WANG Liang，ZHANG Xia
(Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province, Yanshan University, Qinhuangdao 066004, China)
Abstract：This paper proposes a kind of inverter topology and control method with a capability of high-frequency, high-power sinusoidal output. Switching devices with operating frequency equal to that of the output voltage can be used in this kind of inverter. Moreover, it has a good quality of sinusoidal waveform. It is suitable for many applications such as ultrasonic precision machining, cleaning, high-power electrochemical industry, ultrasonic pollution control and so on. By experiments, the parameters about output quality and efficiency are acquired, which demonstrate that the three-level inverter scheme is practicable. 8 Refs. In Chinese.
Key words: three-level inverter; high-frequency sine wave; phase-shifted overlapping; THD
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 1—3.
Research on arc erosion of AgNi alloy contact materials at 50Hz and 400Hz
LI Jing1，2，MA Zhi-ying1, HUANG Shao-ping2，LI Jian-ming2
(1. School of Electrical Engineering，Xi’an Jiaotong University, Xi’an 710049，China;
2. School of Electrical Information，Hunan Institute of Engineering, Xiangtan 411101，China)
Abstract: Using a developed ASTM contact material experimental system of small-capacity and variable frequency, the arc erosion characteristics of the Ag-based contact material at 400Hz were investigated by means of SEM and EDAX during the electric contact current make-and-break test under low voltage, pure resistive load and small current. The values of contact material arcing characteristics of AgNi, AgC and AgW, the changes of AgNi contacts materials surface profile and micro-area constituent were measured and analysed. The surface morphologies and micro-area compositions of AgNi contact material were also analysed, and the reasons of arc erosion of AgNi alloy contact material at AC 50Hz and 400Hz were discussed. 12 Refs. In Chinese.
Key words: 50Hz；400Hz；low voltage；small current；AgNi alloy；contact materials；arc erosion
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 4—7.
Some improvements for surface charge method in calculation of potential and field tensor
ZHANG Yi-fei, ZHANG Zhi-quan
(Department of Control Engineering, Institute of armored Force Engineering, Beijing 100072, China)
Abstract: Some improvements are made on traditional three-dimension surface charge method in view of the traditional one’s low operation efficiency and great memory requirements in calculation of potential and field tensor, which is caused by planar element plot on all kinds of electrode surface and constant approximation for charge density. That is, curved triangular element is introduced to approximate curved surface electrode and expressed by quadratic polynomial, linear or quadratic approximation is adopted to reflect linear or no-linear distribution of charge and tangent plane method is used to solve singularity of fundamental solution of Green function. At the same time, complete implementation of these improvements is provided. At last, two typical examples of the concentric sphere and double cylinder system are calculated, and the results indicate that higher precision and higher efficiency can be achieved with these improvements. So the improved method is correct and feasible.
Key words: surface charge method; calculation on potential and field tensor; leaner or quadratic approximation; tangent plane method
A new kind of three phase alternating magnetohydrodynamic propeller
with double spiral channel
JING Yan，MA Xiu-juan，XU Cheng-bin
(School of Information Science and Engineering, Harbin Institute of Technology at Weihai, Weihai 264209, China)
Abstract: A new kind of three phase alternating magnetohydrodynamic propeller structure with double spiral channel is put forward in the paper, and magnetic shielding and anti-magnetic shielding are introduced in the external spiral channel. Under the different shielding ways, the magnetic field distribution of external spiral channel is analyzed. Finally, the relation is deduced between the electromagnetism force and all kinds of parameters.
Key words: magnetohydrodynamic; propeller; three phase alternating; double spiral channel
Drive strategy of BLDC’s sensorless operation based on high frequency signal injection
ZHONG Li-ping1, XU Hui-gang1，WANG Chang-song2, ZHOU Xiao-min2
(1. Automation Department, Changshu Institute of Technology, Changshu 215500, China;
2. Mechanical Engineering School, University of Science and Technology Beijing, Beijing 100083, China)
Abstract: The method of high frequency signal injection can estimate BLDC’s rotor position in a very wide speed range and thus becomes the first priority to construct a sensorless control system of BLDC. But there still had a trouble to be resolved: for the high frequency signal must be injected by PWM, BLDC couldn’t be driven through power tube’s logical switching. Against this question, a new drive strategy is presented: by controlling the modulating voltage according to the real-time detected rotor position, and the main voltage is also controlled to make sure that it meets the demand of BLDC’s operation, thus the BLDC’s sensorless rotating can be realized. The related experiments are made and the results show that the method is practicable. 11 Refs. In Chinese.
Key words: brushless DC motor; high frequency signal injection; motor start; comutation
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 16—19.
Research on single Li-ion battery charger based on current-doubler-synchronous-rectifier
XIA Hui, JIANG Jiu-chun, LI Jing-xin
(School of Electrical Engineering of Beijing Jiaotong University, Beijing 100044, China)
Abstract: A type of high efficiency single Li-ion battery charger which adopts an advanced technology based on current-doubler-synchronous-rectifier is introduced. A detail operational analysis of this topology is given in this paper. Moreover, a proposal of charge-controlling scheme is provided and the parameters of the whole module are designed in the paper. A designed Li-ion battery charger was realized to verify the feasibility of the proposed module. The experimental results indicate that the module exists lots of advantage, such as small output current ripple, fast dynamic response and the little loss in output inductance filter. 6 Refs. In Chinese.
Key words: Li-ion battery charger; current-doubler-synchronous-rectifier; charge; DC/DC
converter; formation equipment
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 20—24.
Evolutive model of small-world power grid and its power flow analysis
LU Ming-fu, MEI Sheng-wei
(State Key Lab of Power Systems, Dept. of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: Small-world network is a significant network model in complex network theory. The small-world character is found in many huge power grids in the world. Evolutive model of small-world power grid is established based on Complex Network theory, which considered power plant and substation constructed in the process of power grid evolution, including where to build and ascertaining the capability of the power plant and substation, and how to link to system. Topological character is studied during the power grid evolution. Based on the basic idea that network structure decides network function, the power flow of the power grid is analyzed based on DC power flow model. The result shows that small-world power grid gains much more excellent power flow and robustness to the variety of power load demand and different operation modes of power grid. 9 Refs. In Chinese.
Key words: small-world network; power grid evolution; DC power flow; complex network
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 25—29.
Development of a 100kVA three-phase four-leg shunt active power filter
HU Kai1, PAN Meng-chun1, YU Jing-rong2
(1. National University of Defence Technology, Changsha 410073, China;
2. R&D Department of Wasion Energy Industry Technology Co.Ltd, Changsha 410013, China)
Abstract: Three-phase four-wire distribution electrical system with power quality problems such as harmonic, negative sequence, neutral current, occupied a majority proportion in the grid. Three-phase four-leg shunt active power filter (SAPF) provides a perfect solution for power quality problems in three-phase four-wire electrical system. Authors of this paper investigate the FBD theory and propose a reference current detectiong arithmetic by improving FBD method for three-phase four-leg SAPF. The arithmetic is able to divide the load current to fundmental current of different sequences and harmonic current of different frequencies before compensating individual current component. A SAPF rating at 150A output current capacity is designed and implemented employing the proposed arithmetic and four-leg main circuit. The experimental results to compensate different current components are provided. The results show that the equipment can dramatically improve the source current shape by compensating the negative, positive and zero sequence of load current. 14 Refs. In Chinese.
Key words: three-phase four-wire; shunt active power filter; FBD method; four-leg main circuit
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 30—34.
A simple algorithm of trigger angle for step wave modulated cascade inverters
CHEN Yuan-di1,2, LIU Di-chen1, SONG Qing-guo2, ZHU Zhong-ni2
(1. Electrical Engineering Institute of Wuhan University, Wuhan 430072, China;
2. Department of Information Countermeasures of Air Force Radar Academy, Wuhan 430019, China)
Abstract: Besides effectively reducing the voltage stress of switches, the cascaded multilevel inverter could also improve the quality of the output waveforms by addition of waveforms. The step waveform modulation ways can reduce the switching frequency, raise the transition efficiency and reduce the EMI. It is an usual method for the cascaded inverter, but the usual introduced calculating methods of the cascaded inverters trigger angles based on step waveform modulation are not only complex, but also are suitable for cascaded inverters with the same voltage step only. In the light of this situation, the calculating method for the trigger angles of the step waveform modulation cascaded inverters with the different voltage step is proposed in this paper. The method is very suitable for the applications of solar battery cascaded inverters and fuel battery cascaded inverters.
The method follows the equal area principle, and the online calculation is realized by some constraint conditions. Finally, the correctness of the method is validated by simulation results. 18 Refs. In Chinese.
Key words: cascaded inverter; step waveform modulation; trigger angles calculation; different voltage step; multilevel inverter
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 35—40.
Application of CB operating mechanism simulation model in fault diagnosis
AN Tao1, WANG Qing-feng1, TANG Jian-zhong1, YAO Ming2
(1. State Key Laboratory of Fluid Power Transmission and Control, Zhejiang University, Hangzhou 310027, China; 2. Shanghai Municipal Electric Power Company, Shanghai 200025, China)
Abstract: A circuit breakers (CB) operating mechanism dynamic model is established to study the influence of friction force on CB performance for CB mechanical faults diagnosis and prognosis. Simulation and experimanetal results have been obtained to validate the effectiveness of the proposed model. Based on this model, the effect of the changes of friction force on main shaft, trip shaft etc. on CB performance is analyzed, and the results show that the increase of friction force on key shafts could cause some serious faults on CB such as resisting closing, resisting opening which could be prognosticated by observing the features constructed from the proposed model. This study provides a significant criterion for research and development of fault prognosis for CB operating mechanism.
Key words: circuit breaker; operating mechanism; simulation models; friction force; faults diagnosis
Cancellation of parasitic inductance for filtering capacitor with planar windings
CUI Yong-sheng，WANG Shi-shan，ZHOU Xiao-lin，XIE Shao-jun
(Nanjing University of Aeronautics and Astronautic，Nanjing 210016，China)
Abstract: The capacitors of filters are important components to suppress interference, and the high-frequency performance of it suffers from the parasitic parameters. A new type of eliminator using PCB windings is designed to effectively eliminate the parasitic inductance of capacitors in this paper. As will be shown, the secondary parasitic capacitance is effectively reduced because of the windings interlaced without affecting the size or cost of the filter. The principle of cancellation and problems of secondary capacitance are analyzed, and the eliminator using PCB windings interlaced is introduced. The 3D finite element model is presented and the comparison of the calculated and measured mutual inductance validates the modeling method. Finally, such planar eliminators for parasitic inductance cancellations are applied to capacitors, and applicable design rules are established and experimentally validated. 11 Refs. In Chinese.
Key words: capacitor; parasitic inductance; secondary parasitic capacitance; planar eliminator; finite element model
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 45—48.
Study of applications based on superconducting power technology in smart grid
CHEN Zhong1, XIAO Li-ye2, WANG Hai-feng1
(1. Southeast University, Nanjing 210096, China; 2. Inst. of Elec. Eng., Chinese Academy of Sciences, Beijing 100080, China)
Abstract: The applications based on superconducting power technology in smart grid are studied in the paper. Smart grid will be an important development direction of the electric power industry in China and the superconducting power technology will be the feasible solutions to the development of smart grid. Based on current power system features in China, the prospective applications of superconducting power technology in the smart grid are discussed in the paper from the view point of power system. The superconducting magnetic energy storage technology, superconducting cable technology, the superconducting current limiting superconducting device technology and other new technologies are focused on especially from the application prospect of major research and development directions. 16 Refs. In Chinese.
Key words: superconducting technology; smart grid; superconducting energy storage; renewable energy
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 49—53.
Study of piezoelectric cantilever for power generation
GONG Li-jiao1,2, SHEN Xing2
(1. Machinery and Electricity Engineering College, Shihezi University, Shihezi 832003, China；
2. Aeronautics Science Key Laboratory for Smart Materials and Structures, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China)
Abstract: The mechanism of electric charge appearance is described when the PZT-metal composite cantilever is under the force action. Then the piezoelectric device for power generation was designed and fabricated. The experimental system was setup. And experimental study was made to analyze the effect of energy conversion of bending vibration and power generation output. In the experiments of single frequency stable state sine wave vibration, the shaker was connected to an amplifier with sine wave function generator. When the shaker vibrated, the piezoelectric device would vibrate and bend at a certain frequency and amplitude. The results show that under given conditions, the device can be used to convert the bending vibration energy into useful electrical power and a power of 88.8 μW is available. The experimental results prove that the PZT-metal composite cantilever can be likely used for the micro energy conversion in the low frequency environment.
Key words: PZT-metal composite cantilever; power generation; vibrations; micro power
A resistance divider for measurement of high voltage pulse with fast rise time
MA Lian-ying, ZENG Zheng-zhong
(Northwest Institute of Nuclear Technology, Xi’an 710024, China)
Abstract: The effect of inductance and capacitance of resistance divider on its responding characteristic is analyzed. Based on the result of the analysis, according to the rise time of the pulse which needs to be measured, the maximum inductance and capacitance of resistance divider are figured out, and a coaxial and compact resistance divider is developed to measure high voltage pulse with about 2ns rise time and 10kV amplitude and its calibration is also carried out. The divider has been applied to experimental measurement, and the experimental results show that the coaxial resistance divider can satisfy the measurement requirements and can be used in the measurement of short pulses with maximum amplitude of about 10kV and rise time of ns level. The divider has superior performance and is easy to use.
Key words: resistance divider; fast rise time pulse; coaxial structure
Experimental research on temperature control of PV cells of TPV system
TAN Hong, HAN Yu-ge, YANG Tao, XUAN Yi-min
(College of Power engineering, Nanjing University of Science and Technoloyg, Nanjing 210094, China)
Abstract: The temperature of PV cells is one of the factors which decide the efficiency of cells in the thermophotovoltaic (TPV) system. The filter can decrease the temperature of PV cells. In order to control the temperature of PV cells, a gas-cooled system and a water-cooled system are designed, and the experiment results show that the temperature of PV cells decreases gradually with the increase of cool fan power. At the same temperature of radiator, the temperature of cells which using the water coolant is lower than that using the air coolant. The output power of cells increases with the decrease of the temperature of cells. 8 Refs. In Chinese.
Key words: TPV; filter; gas-cooled; water-cooled; efficiency
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(1). 62—66.
Algorithm of generating SSD documents in system description tool based on IEC61850
ZHAO Han1, CHANG Hong1, LIU Xiao-hui1，CHEN De2
(1. Electrical Engineering College，Xi’an Jiaotong University, Xi’an 710049, China;
2. Xi’an University of Posts and Telecommunications, Xi’an 710061, China)
Abstract: In order to reduce workload of the substation developer and improve the development efficiency, this paper designs a new system description tool named Visual SSD after studying in-depth the XML/Schema technology and graphical interactive technology. Visual SSD can generate the SSD file even if the substation workers don’t know the SCL technology. Firstly, the IEC61850 Standards and basic format of the SSD document is analyzed in detail. Then a method which can generate a SSD file automatically is designed, which is based on the LINQ to XML technology. Thanks to a new algorithm put forward in this paper of how to form a SSD document from a graphical wiring diagram, the generation of the SSD file is finally realized with the .net C# and LINQ to XML technology. Now Visual SSD can be used easily to get a very important file SSD in the substation system description based on IEC61850 automatically. Moreover, the algorithm introduced in this paper also can be used in generation of SCD、ICD、CID files.
Key words: system description tool based on IEC61850; SCL; generation algorithm of SSD film
On-line system for monitoring galloping of transmission line based on embedded system
WEN Jun1，HE Wei1，QIAO Xiao-yan2，LI Luo1
（1. State Key Lab. of Power Transmission Equipment & System Security and New Technology (Chongqing University), Chongqing 400044, China; 2. Dazhou Power Supply Bureau, Sichuan Electric Power Company,
Dazhou 635000, China)
Abstract: An on-line system for monitoring galloping of transmission line based on embedded system is presented. It consists of USB camera, embedded computer and GPRS module. In the system embedded system Linux is cut down, customized and ported into the embedded system, for which the monitor software based on Qtopia is also developed. The system is based on the image data of USB camera acquisition, and using embedded computer as baseplate. The system can tele-monitor the transmission lines of power equipment through GPRS.
Key words: galloping of transmission line；embedded computer；USB camera；wireless GPRS
Application of neuron-PID and voltage space vector control technology in DSTATCOM
DAI Ya-pei, LUO An, PENG Chu-wu, WU Chuan-ping
(Hunan University, Changsha 410082, China)
Abstract: In order to satisfy the requirements of reactive power compensation and to improve voltage quality in distribution network, the direct current control strategy based on neuron-PID and the modulation method based on SVPWM for distribution static synchronous compensator (DSTATCOM) are proposed. The current instruction can be easily obtained by simple algebraic operation and this method has certain adaptive learning ability. Distribution static synchronous compensator based on neuron-PID direct current control strategy can compensate system reactive power, improve power factor, and keep the dc side voltage stable effectively. In order to eliminate the negative effect of high switching frequency brought by direct current control, voltage space vectors control method is used. The application principle of voltage space vectors is studied and r1r2r3 coordinate system is introduced which is used to calculate function time and area. Experiments have proved the validity of SVPWM technology and neuron-PID applied to distribution static synchronous compensator (DSTATCOM).
Key words: neuron-PID; direct current control; SVPWM; DSTATCOM
|
