Measurement and Suppression of Common-mode and Differential-mode EMI in PWM Converter System
XUE Wen-yan1, YUAN Qi-long2, MA Xi-kui1
(1. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China;
2. Xi'an University of Technology, Xi’an 710048, China)
Abstract：This paper discusses how to reduce conducted electromagnetic interference (EMI) in an AC/DC converter system to accord with EN class A. Herein some passive methods of suppressing conducted EMI noise, such as mixed-mode (MM) EMI filters, snubbing circuits, are used. Based on measurement, the sources of noise are detected with characteristics analyzed in detail. The MM EMI filter is valuable means with which the conducted EMI noise can be effectively reduced. A simple method of designing EMI filter, combining theoretical calculation with practical modification, is presented. It is easily implemented with only the amplitude of noise and sink impedances required. The experiment results prove that the methods adopted are viable and effective.
Key words：power electronics; AC/DC converter; conducted EMI; EMI reduction; EMI filter
Accurate calculation for random faults of double circuit line on loop net
LIN Jun
(College of Electric Engineering, Fuzhou University, Fuzhou 350002, China)
Abstract: On loop power net, it is hard to obtain the system impedances at both sides of double circuit line that makes fault calculation difficult. An accurate calculation method for random faults of double circuit line on loop net is introduced. By a precise model of distributed parameters and eigenanalysis method, considering the effects of power line transposing and distributed capacitance, the calculation method can precisely get random fault (including crossing lines faults and complex faults) results of double power lines on the same tower. With an example of two lines short and grounding fault，and one side of breaker of grounding fault line being cut off, the paper illustrates the principle of this calculation method.
Key words: double circuit line; accurate calculation for random faults; model of distributed parameter; eigenanalysis; loop net
Multi-agent based operation instructing system in substation
JIANG Hui-lan , LIU Jie , LIANG Zhao-jun , YUE Ya-lin
(1. Tianjin University, Tianjin 300072, China;
2. High Voltage Power Supplied Company, Tianjin 300250, China)
Abstract: The operation instructing system in substation of power systems is an important guarantee for secure and reliable operation in substation, so it is more significant to making up correct switch operation-order-sheet for the operation and maintenance management of substation. This paper proposes to apply multi-agent theory of distributed artificial intelligent technique in operating-order-sheet automatic generating system and build a distributed MAS system to accomplish the operation instructing system in substation. This system consists of devices’ operating sequence’s generating Agent, checking Agent, misoperation prevention Agent and coordination control Agent. For every sub-Agents of devices’ operating sequence’s generating Agent which plays kernel function in whole system, RBFNN is adopted to accomplish hidden inference to gain device operating sequences by using the performance of strong associative memory and high fault-tolerance of RBFNN, so that some of the disadvantages of expert system technique can be avoided. Study shows that this system has the characteristics of simple realization processing, convenient maintenance management, and high intelligence, plays intelligent assistant function for field operation and management.
Key words: substation; multi-agent; operation sequence; RBFNN
Neural network based design model for intelligent AC contactor
in breaking course
XU Zhi-hong, ZHANG Pei-ming
(College of Elec. Eng. & Automation, Fuzhou University, Fuzhou 350002, China)
Abstract：Dynamic calculation is very important for intelligent AC contactor to realize the zero-current-break control in breaking course. The paper sets up a neural network based design model for intelligent AC contactor in breaking course. The new method is proposed for dynamic calculation and analysis of intelligent AC contactor in breaking course. The principle for studying the products and virtual optimization design is established.
Key words：intelligent AC contactor; breaking course; neural network; predict; model
3-phase current-source-rectifier based on DSP and CPLD
WANG Fu-sheng, LIU Xiao-ning, PAN Sheng-ming
(Institute of Plasma Physics, Academia Sinica, Hefei 230031, China)
Abstract: A novel 3-phase, Current-Source-Rectifier circuit strategy is presented in this paper. Based on dynamic trilogic-PWM and a simple feedback control strategy, the proposed topology and control strategy guarantee that the current of DC side traces precisely the given value. In addition, the power system can achieve unity-power-factor and harmonic free. The main circuit, control strategy and control system based on DSP and CPLD are described in detail in this paper. A 1.0KW experimental model has been established to verify control strategy and the experiment results are well consistent with the theoretical results.
Key words: current-source-rectifier (CSR); trilogic-PWM; control strategy; unity-power-factor; DSP; CPLD; experimental model
Partial discharge of UHF pattern recognition in transformers
using adaptive neuro-fuzzy inference system (ANFIS)
LI Yan-mu 1, YUAN Peng2, MOU Lei2, LI Yan-ming2
（1. Dept. of Mechanical and Electrical, Xi’an University of Architecture and Technology, Xi’an 710055, China; 2. Dept. of Elec. Eng., Xi’an Jiaotong University, Xi’an 710049, China）
Abstract：Features of partial discharge (PD) in transformers is extracted by Ultra-High-Frequency PD monitoring system. Firstly, according to the priorities of features，six of them are selected as the input variables of the adaptive neuro-fuzzy inference system(ANFIS). Next, the ANFIS model of six inputs and one output is presented. Takagi and Sugeno’s fuzzy if-then rules are used. Hybrid learning algorithm combining the gradient method and the least squares estimate (LSE) is adopted to train the ANFIS. Finally, the availability of ANFIS is tested. The results showed that the method based on ANFIS is feasible in PD pattern recognition.
Key words: partial discharge; pattern recognition; ANFIS; transformer
Modeling and electromagnetic optimization
based on combined optimization method for solenoid superconducting magnet
SONG Ming1, Liu Xiu-cheng1, WANG Zan-ji2
(1. Dept. of Elec. Eng. and Applied Electronics, Tsinghua University, Beijing 100084, China;
2. State Key Laboratory of Control and Simulation of Power Systems and Generation Equipment, Beijing 100084, China)
Abstract: Focusing on the design of the solenoid superconducting magnet which is extensively applied in many superconducting systems, this paper proposed a novel optimization method which comprehensively takes the energy, the stray field and the volume of the magnet into consideration. The electromagnetic model of the multi-solenoid superconducting magnet for the optimization is worked out based on the magnetic field calculation for the single solenoid magnet, and the stray field and the maximum fields of the multiple parallel solenoids are calculated with the method of vector superposition. Combining with global search and traditional mathematic programming, the established model is optimized. The results show that the satisfactory electromagnetic optimization design of the solenoid superconducting magnet can be obtained using the proposed method.
Key words: superconducting magnet; magnetic field calculation; optimal design
Modeling and simulation of impact responses of ship used air circuit breaker
KANG Yan1，CHEN De-gui1，ZHANG Jing-shu 1，SHI Jin-wu 2
（1. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China；
2. Shanghai Electrical Apparatus Research Institute, Shanghai 200036, China）
Abstract: ACB (Air Circuit Breaker) impact response characteristic during impact loads is a critical concern for the reliable work of naval ship power system. Instead of impact test method，a new approach is discussed in this paper, which built the mathematics model and created a finite3-D element model of ACB firstly, and then made the dynamics simulation for ACB impact model. According to this, impact responses of ACB, such as displacement, acceleration, strains, and energy, are analyzed respectively under different impact mass values and directions. Finally, the paper presents some useful suggestion for the anti-impact design of ship used ACB．
Key words: air circuit breaker；impact response；simulation of dynamics
Dielectirc wall accelerator
YAN Ping, WANG Jue, ZHANG Shi-chang
(Institute of Electrical Engineering, Academy of Sciences, Beijing 100080, China)
Abstract: In this paper, the new accelerator concept – dielectric wall accelerator (DWA), its developments and key technology are introduced. DWA is brought forward by G.Caporaso and his fellows in the 1990s. The DWA is a new accelerator concept particularly suitable for short pulse (<50 ns) and high currents (>1 kA). The pulsed acceleration field is developed by a series of asymmetric Blumleins incorporated into the high flashover electrical field insulator structure. A conventional induction machine has an accelerating field only in the gap, which occupies a relatively small fraction of the axial length of an accelerating cell. If the DWA technology is adopted, the conducting beam pipe could be replaced by an insulating wall, and accelerating fields characteristic of the gaps might be applied uniformly over the entire length of the accelerator yielding a much higher gradient. The high flashover electrical field insulator, asymmetric Blumleins and high speed switch are key techniques of DWA.
Key words: linear induction accelerator; asymmetric Blumlein; high speed switch; high gradient insulator; dielectric wall accelerator
Discussion on utilization of regenerated energy
LIU Hui-jin1, CHEN Li1, CHEN Ge-huan2
(1. Wuhan University, Wuhan 430072, China;
2. Guangdong Electric Design Institute, Guangzhou 510600, China)
Abstract: At present, cities of our country generally deal with the rubbish by burying. This way has already taken up a lot of land and polluted the environment. Using rubbish to generate electricity is an effective way to solve municipal refuse and realize rubbish reutilization. The garbage power generation has both good social and economic benefits. It is a new form of generating power. It has important meaning to the environmental protection of cities. Its main function is to burn rubbish rather than to generate electricity, so the principles of construction of refuse incineration power plant are different from that of routine power plant. The basic principles of constructing refuse power plant are: to reduce the construction cost of the project and to strengthen the supervision during operation so as to keep the discharge of wastes within the standards.
Key words: garbage power; resources development and utilization; construction; principle
Application of finite difference time domain method in partial discharge detection of GIS
CHEN Wen-hui1, LI Zhong2
(1. School of Electronic and Information Engineering, Northwestern Polytechnical Uiversity, Xi’an 710072, China；2. School of Elec. Eng., Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Finite-difference time-domain (FDTD) method is an efficient method for calculation of electromagnetic field. This paper uses FDTD method to simulate the electromagnetic wave propagation of partial discharge excited in gas insulated switchgear (GIS), analyzes the influence factors, and measures the partial discharge in GIS bus bar in laboratory. The results of simulation and experiment are in agreement. These results demonstrate that using ultra-high frequency (UHF) is efficient and feasible, and this method can be used for partial discharge detection on-site.
Key words: finite-difference time-domain (FDTD) method; gas-insulated switchgear (GIS); partial; discharge (PD); detection; ultra-high frequency (UHF)
Research on static series compensator of distributed flexible AC transmission systems
NING Gai-di，WANG Yue，WANG Zhao-an，LONG Yun，XIAO Guo-chun
(School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract：Distributed Flexible AC Transmission Systems (D-FACTS) is new way of FACTS. It uses a large number of distributed static series compensator (DSSC) modules that can be clipped on to an existing power line to control power flow, relieve congestion, limit loop flows and improve the power transfer capacity. This paper makes descriptions on configuration and basic principles of DSSC. An experimental system of the DSSC based on active variable reactance is designed. The simulation and experimental results are presented, verifying that designed DSSC has good function of power flow control, Configuration of DSSC be fit for D-FACTS.
Key words: flexible AC transmission systems (FACTS); distributed FACTS (D-FACTS)；compensator; power flow control; power transmission lines
A novel high precision phase-locked method for UPS based on DSP
MA Xue-jun1.2, CHEN Xi-kun1, KANG Yong1
(1. Huazhong University of Science & Technology, Wuhan 430074, China;
2. Huangshi Polytechnic Institute, Huangshi 435003, China)
Abstract: In this paper, the principle and realization method of DPLL (Digital Phase- Locked Loop) with high precision by DSP TMS320F240 is presented. The phase error between UPS and electrical network is sensed by Schmitt Trigger corresponding with AC and recorded by CAP interrupt and period interrupt of DSP. A Digital PI controller is applied to supply a compensation value for every carrier period. The control strategy and the flow chart of program are given. The dynamic tracing of inverter output to electrical network is realized by dynamic changing carrier period. The theoretical resolution of phase error is 0.72 degree. A linear model in z domain is built. Simulation result shows phase-lock is completed only after 0.06s.The dynamic performance is good. A prototype with 50Hz/220V/1.4KW is made to verify the method of DPLL. Experimental results prove the scheme is feasible.
Key words: UPS；DPLL；high precision; DSP interrupt
Study and implementation of magnetic stereotaxis system
YANG Ming1,2, BAI Ye1,2, WANG Qiu-liang1, YU Yun-jia1
(1. Institute of Electric Engineering, Chinese Academic of Science, Beijing 100080, China;
2. Graduate School of the Chinese Academy of Sciences, Beijing 100039, China）
Abstract: In order to detect the target space position at the prophase of the Magnetic Stereotaxis System, we use double-camera computer vision to detect the position of small permanent pellet. The implementations of the experimentation are described in this paper in detail. For the space position, the algorithm of computer vision mainly includes: camera calibration, pre-process of image and feature distill, feature matching, three-dimensional size measurement and space reconstruction. In order to meet the requirements of space position for the MSS, an on-line measuring system of double matrix CCD in VC++6.0 was developed. The target movement route is shown on the monitor. And then the space position is transferred to the next control system which controls the target to move in a certain route. A lot of experiments have been done based on the software MSSLocater1.0, the experiment results show that our space position system is acceptable for present MSS.
Key words: MSS; space position detect; computer vision; small permanent pellet
Development of automatic detection system of motor commutating segment
based on image recognition technology
ZHANG Jian-hui, SONG Ping-gang
(School of Electrical and Electronic Engineering, East China Jiaotong University, Nanchang 330013, China)
Abstract: The paper proposes a new automatic detection system of motor commutating segment, introduces the principle and the frame of hardware of the system, and presents an image processing method that is suitable in this system. Afterwards, this paper accomplished the software programme and the design of system interface with VC++6.0. During the experiment, the commutating segment of ZQDR-410 motor was detected, and the orientation signal of digital machine tool was obtained. The experimental results show that the system works well in both precision and real time performance, so it is valuable for practical application.
Key words: CCD camera；image recognizing；calibration；commutating segment
Research on optical fiber communication system of medium-voltage inverters
CUI Zhi-liang，ZHAO Zheng-ming，YUAN Li-qiang，LIU Jian-zheng，ZHANG Hai-tao
(Dept. of Electrical Engineering, State Key Laboratory of Control and Simulation of Power System and Generation Equipment，Tsinghua University, Beijing 100084, China)
Abstract: With the application of novel IGCT devices and optical fiber, almost all the system signals can be transferred by optical fiber in Medium Voltage (MV) inverters. To have the Electro Magnetic Capability (EMC) of system signals, and to improve the speed and accuracy of triggering, protecting and communicating signals, which are involved in MV inverters, have become a hot spot recently. Based on the advantages of optical fiber communication and improvement of the interface circuit, the communication system of MV inverters is analyzed in detail, and the performance of the communication system is presented and verified by experiments.
Key words: MV inverters; GCT; optical fiber communication; electro magnetic interference
Design and calibration of measuring probes on 0.1 TW pulsed power source
YUAN Jian-qiang, ZOU Xiao-bing, ZENG Nai-gong, LIU Rui, LI Peng,
WANG Xin-xin, HAN Min, ZHANG Gui-xin
(Department of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: Based on the coaxial cylindrical structure of pulse transmission line (PTL) of a 0.1 TW pulsed power source, a capacitive voltage divider was designed and inserted in between the inner tube and the outer tube of the PTL. A stainless steel film connecting the outer tube of the PTL and load was designed as pulsed current monitor. The capacitive voltage divider and the current monitor were calibrated on line. The voltage ratio of the capacitive voltage divider was determined to be 418.5 with an accuracy of 4.6 % and the resistance of the stainless steel film 1.43 with an accuracy of 5.1 %. The results show that the capacitive voltage divider and the current monitor are ideal probes for measuring high pulsed voltage and current.
Key words: calibration; capacitive voltage divider; current monitor
