Abstracts of Vol.24, Issue 3, 2005

AC servo system with multi-mode coordinated controllers
based on intelligent integral
WANG Rui-ming, JIANG Jing-ping, ZENG Yu-jin
(College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China）
Abstract: In order to satisfy the requirements of higher accuracy and faster response of AC servo system, an AC servo system with multi-mode controllers based on intelligent integral is designed in this paper. The effectiveness of the system was analyzed. The analysis and proposed methods were verified by simulation and experimentation. The results of simulations and experimentation show that the result of this method has a good control effect on both regulating and set-point following. For AC system in practice, it has a quite good disturbance resistance and a strong robustness. Both dynamic and steady performance are improved evidently and the results are satisfactory.
Key words: fuzzy controller; AC servo system; intelligent integral; multi-mode coordinated control

Study on coupling characteristics of contactless power supply system
for moving apparatus
WU Ying, YAN Lu-guang, XU Shan-gang
(Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100080, China)
Abstract: New contactless power supply system implements contactless power transmission by the combination of electromagnetic inductive coupling and power electronic technology. For moving apparatus air coil structures have some potential advantages over the iron core structures, such as, lightweight, good coupling stability with horizontal displacement etc. This paper does the calculations of self-inductance for coils with different shape and mutual inductances between coils with displacement by the magnetic flux method and Neumann’s formula. Further study has been given on the effect that the coil shape and dimensions have on the coupling change characteristics. Finally the results acquired have been validated by the experimental research. The experimental and calculated results show that the rectangular coil is more effective for stabilizing the coupling in the contactless power supply system for moving apparatus, which is mainly determined by the coil width and the length ratio between the primary and the secondary. The smaller the width and the larger the length ratio, the better the coupling characteristic with displacement.
Key words: moving apparatus; contactless power supply; air coil; coupling characteristics

Optimal design of intelligent AC contactors based on ant colony algorithm
XU Zhi-hong, ZHANG Pei-ming 
(College of Electrical Engineering & Automation, Fuzhou University, Fuzhou 350002, china)
Abstract: Ant colony system is a novel simulated evolutionary algorithm, which provides a new solution for complicated combinatorial optimization problem. In this paper, the algorithm is used for the optimized design in electromagnetic device of intelligent AC contactor. The magnetic properties and the control parameters of the contactor are studied. The contactors will have more suitable electromagnetic device and action characteristics. The contactor will have better performance. The operation dependability of contactor is improved greatly, and saving-material (especially silver) and saving-energy are realized.
Key words: ant colony algorithm; intelligent AC contactor; optimal design

Improved genetic algorithm and neural network’s application
in the recognition of power quality disturbances
OUYANG Sen
(College of Electric Power, South China University of Technology, Guangzhou 510640, China)
Abstract: A new Improved Genetic Algorithm (IGA) was proposed in this paper. In the IGA, the effective selection and cross strategy was adopted, and the new adaptive probability algorithm of crossover depending on the number generations, and a new adaptive probability algorithm of mutation depending on the fitness value were designed. Moreover, a crossover strategy for preventing inbreeding is also proposed. All these methods can help to enhance the capability of the genetic algorithm. IGA is also used in the recognition system based on the BP neural network, to improve its stability and convergence capability. Finally, the validity of the proposed method is verified by the results of the simulation.
Key words: genetic algorithm; crossover probability; neural network; power quality

Study on the compensation delay and its countermeasure of active power filter
LI Hong-yu, WU Long-hui, ZHUO Fang, WANG Zhao-an
(Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: The effect of compensation delay, which is caused by compensation reference calculation and current control, on the performance of active power filter（APF）is analyzed. It can be seen that the compensation of high order harmonics is degraded seriously by even small time delay. The reason causing time delay is analyzed in case of digital control and digital-analog hybrid control. Then the current control method without compensation error is figured out. On this basis, a simple and effective phase compensation method is presented to compensate the time delay caused by compensation reference calculation and current control. Moreover, a simple predictor is implemented to improve the dynamic performance of APF, which essentially does not increase the complexity of calculation. Finally, testing results on an experimental shunt APF are presented to validate the proposed method.
Key words: active power filter; compensation delay; predictor

Application of reactive power compensation on islanding detection
of grid-connected PV system
YU Hua-jun, PAN Jun-min
(Department of Electric Engineering, Shanghai Jiaotong University, Shanghai 200030, China)
Abstract: A new method for islanding detection is presented, and the status of the islanding can be detected by the change of the frequency of the load voltage. The optimal detection performance is achieved when the appropriate RPC (reactive power compensation) strategy is used, which is in accord with the characteristics of the loads. The theory of the islanding detection using the variable reactive power generation from the inverter is investigated primarily. The simulation results validate the feasibility of the RPC method to detect the islanding. At last, the effects of the matching degree of the active power and reactive power between the power resource and the local loads on the frequency of the load voltage are analyzed by the simulation results.
Key words: islanding; grid-connected; reactive power compensation; power matching

Research on dynamic contact resistance measurement and failure prediction
of relay contacts
CHEN Peng, LU Jian-guo, YAO Fang, LI Xin
(Hebei University of Technology, Tianjin 300130, China)
Abstract：The contacts voltage of counterpart contacts in the close course of electromagnetic relay is observed and recorded in its failure tests using dynamic contact resistance measurement system. It is found that the voltage varies with time and its wave takes on complicated variation and attenuation. Also, the contact experiences dynamic bouncing, tiny vibration and static state with time. The analysis on test data shows that the contact failure of relay, to a certain extent, is related to the bouncing time and the maximum value of contact resistance in the close course. Therefore, the curve of variation of bouncing time to operating times and maximum value of contact resistance can be considered synthetically for forecasting contact invalidation of relay.
Key words：electromagnetic relay; contacts; failure prediction

Non-linear modeling and simulation of induction motor
LU Hai-feng, QU Wen-long, ZHANG Lei, FAN Yang
(The State Key Lab of Safe Control and Simulation of Power System and Generating Equipment,
Tsinghua University, Beijing 100084, China）
Abstract: A new simplified and practical nonlinear model of induction machine in stationary reference frame is presented in this paper. It has satisfactory accuracy and possesses concise equivalent circuit form. In this proposed model, both the fictitious flux and nonlinear saturation factor are introduced for considering the effect on motor magnetic circuit saturation, and the eddy and hysteresis losses are also taken into account through a parallel resistance in the equivalent circuit. In the absence of detailed motor design information, the parameters in the model can be easily determined by the conventional no-load and lock-rotor tests. An improved method of simulation with the model is described, which is suitable to program with C/C++ or S-Function of Simulink. Both the experiment and simulation results have verified the practicality and effectiveness of the model.
Key words: induction motor; nonlinear modeling; simulation; fictitious flux; saturation factor

Loop type conversion and regulation of line flow violation based on loop analysis
 WANG Cheng-min1, JIANG Chuan-wen1, HUANG Rui2
(1. Dept. of Elec. Eng., Shanghai Jiaotong University, Shanghai 200030, China;
2. Guangxi Qinzhou Power Bureau, Qinzhou 530021, China)
Abstract: Node voltage and loop current functions of electric power network are established on the base of equivalent  -model network, with loads equivalent to a voltage source and impedance branches to the link branches and grounding branches to the tree branches, in order to expand the power flow equations as node voltage formulas with loop current formulas and to express the Jacob matrix as function with node voltage and loop current variables; in addition, the loop type and Q  node type are defined. The loop and node types are transformed so as to regulate the injected nodal active powers and to control the line flow which limit is violated. The case study is made at IEEE-30 system and the better effect is proved.
Key words: node voltage; loop current; power flow calculation

Study on accurate calculation for non-complete phases condition
of double circuit line and its single-pole reclosing
LIN Jun, TANG Qi
 (College of Electric Engineering, Fuzhou University, Fuzhou 350002, China)
Abstract: By precise model of distributed parameters, running condition of a 500kV double circuit line with the non-complete phases is calculated, with or without parallel reactors. The phase relationship of voltages between fault line and no-fault lines is analyzed both under permanent fault condition and instantaneous fault condition. The integrating criterion for distinguishing permanent or instantaneous fault condition is put forward using voltage amplitude of fault-phase, phase relationship of voltages between fault line and no-fault lines, and harmonic of fault phases voltage. By this method, the single-pole reclosing under selected condition can be completed and the impact on the power system and equipments through reclosing on the permanent fault line could be avoided.
Key words: double circuits; fault calculation; non-complete phases condition; single-pole reclosing; non-complete phases condition

Analysis of nonlinear modal interactions
in HVDC/AC power system using modal series method
ZHENG Yun-hai, LI Xing-yuan
(Sichuan University, Chengdu 610065, China)
Abstract: In this paper a new method of studying the nonlinear dynamic behavior is introduced and extended to HVDC/AC power systems. Based on Taylor series expansion and nonlinear transformation of the state space, the method makes it possible to obtain a closed form solution, which includes the frequency-domain information and nonlinear modal interaction indices. Using modal series method the nonlinear behavior of the power system can be analyzed. In this paper the modal series method is applied to a three-generator HVDC/AC power system and analysis is made to show the effect of modal interactions.
Key words: modal series; HVDC/AC; nonlinearity; modal interaction

Output direct feedback of flyback switching power supply based on UC3842
XIE Ye-yuan1, QIAN Zhao-ming1, PENG Fang-zheng1, 2
(1. Zhejiang University, Hangzhou 310027, China;
2. Michigan State University, East Lansing, MI 48824, USA)
Abstract: This paper presents a novel method to control the flyback switching power supply through analyzing the small-signal model of flyback circuit. A new application of UC3842 in a flyback switching power supply has been put forward to perform feedback from output directly. By means of the two methods, the small-signal model of CPM flyback switching power supply is established and the trans-function of each circuit is introduced. The simulation result using Matlab is in excellent agreement with the analysis of trans-function. Compared with the traditional control strategy, it has many advantages, such as, faster dynamic performance, higher close-loop gain, better stability, lower output voltage ripple, lower load regulation and lower input voltage regulation, etc. In addition, the new control strategy discards the design of PI network, which leads to choose circuit parameter easily and easier to be stabilized. The experimental results verify the analysis.
Key words: transfer function; flyback; CMP; switching power supply; pulse width modulation

Treating Dyeing Wastewater by Combination of DC Electrocoagulation
and Biochemical Method
Yue Bo, Tao Yuan, Ma Minhua, Wang Liming
(Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055)
Abstract: Printing and dyeing industry is one of largest water consumption industries. High colourity, large COD and PH are the main characteristics of dyeing wastewater, which color varies frequently during the production. Conventional biochemical treatment has reached its technical limit and is hard to improve its treatment effectiveness. Firstly, treatment of real dyeing wastewater by electrocoagulation with iron or aluminium electrode was studied in a dying factory in the paper. The improvement of COD and colority, change of PH, and power and electrode consumption were analyzed and the relative parameters are selected in the paper. Secondly, the simulation experiment by combination of DC electrocoagulation and biochemical method was make in a factory and has been continued for six months. The experimental result shows that the combination method can supply each other and combine the advantages of two methods. It can decrease COD and colourity efficiently with wide PH arrange, simple technics, convenient operation and low cost.
Key words: Dyeing wastewater; electrocoagulation; biochemical Method

Interoperability analyses and system implement to IEC61850
semantic information model
CHANG Hong1, RU Feng2, XUE Jun-yi1
(1. School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China;
2. Jiangsu Provincial Electric Power Research Institute, Nanjing 210036, china)
Abstract: IEC61850 ─ international standard for substation automation system is absorbing many experts concerns. Many researches are focusing on how to develop IEC61850 networks system. It is seldom to discuss the interoperability, the important aim of IEC61850, through theoretical method that could be use to direct the networks realization. In this article, the interoperability of semantic information modeling of IEC61850 is investigated from formal semantic theory. Such conclusions are deduced: 1) the semantic information modeling specified in IEC61850 is the basis for application of various techniques; 2) All techniques which used in substation automation communication system should be isomorphic based on the semantic model complete set in order to reach real interoperability. Based on these important conclusions, the general architecture of the substation automation communication network of IEC61850 is put forward and the functions of semantic manager are described.
Key words: semantic information model；formal semantic；interoperability；IEC61850

Research of three phase inverter bridge supply SRM
HUANG Hai-hong, WUANG Hai-xin
(Hefei University of Technology, Hefei 230009, China) 
Abstract：A star type connection is adopted on a three phase SRM (Switched Reluctance Motor), supplied with a three phase inverter bridge. It could not get good result with traditional control methods. According to the principle of SRM’s electromagnetic torque, this paper analyzed its self-inductance and mutual-inductance’s effect on electromagnetic torque. With the rule of their variation, this paper used special symmetric and uneven excitation mode with 720°electric angle a cycle, and good result was obtained. It can solve the problem of excessive connecting lines between SRM and power supply. Based on the sample motor, this paper analyzed the excitation mode theoretically, and the result was validated with experiment.
Key words：switched reluctance motor; dissymmetry half bridge; star type conjunction; symmetry and uneven excitation mode

Application of FB-ZVS-PWM converter in inductive hot-water heaters
LIU Quan-hai1, WEI Li2, ZHANG Xiao-jie1
(1. Shaanxi Polytechnic Institute, Xianyang 712000, China;
2. Xi’an University of Science and Technology, Xi’an 710054, China)
Abstract: In this paper the electric-hot-water exchange process, load characteristic of inductive hot-water heaters and the working state of IGBT-FB-ZVS-PWM resonance converter were analyzed. According to the wave of the sample and the result of comparing the performance with hard-switch converter, the basic design principle for IGBT-FB-ZVS-PWM resonance converter was proposed which ensure the large-scale inductive hot-water heaters to run at supersonic frequency, low noise and low consumption.
Key words: inductive hot-water heaters；resonance converter；phase-shifted control；noise

Study on communication system for combined vacuum magnetic switchgear
in 3.3kV underground distribution networks based on multi-CPU control
ZHENG Li-jun1, SHI Wang-jie2, SUN Yi-qi1, WANG Xin-ye1, SONG Jian-cheng1
(1. College of Electrical and Dynamical Engineering, Taiyuan University of Technology, Taiyuan 030024, China; 2. Sihe Colliery, Jincheng Coal-mining Group, Jincheng 048000, China)
Abstract: The significance of communication among several CPUs and between CPU and intelligent display for combined vacuum magnetic switchgear is analyzed in this paper. And then, the theory of multi-CPU communication is introduced and the communication protocol is formulated. The practical scheme of communication system between PLC and microcontroller, PLC and PLC, touch panel and PLC is designed. Meanwhile, the method of implementation by use of hardware and software is proposed and the novel strategy to control multi-motors coordinately by means of real-time communication between single chip computer and PLC is developed. It has been proved by the field tests that the multi-CPU communication system is feasible in the scheme, exact in the data processing and quick in the data transmitting.
Key words: microcontroller; programmable logic controller; touch panel; communication system; vacuum magnetic switchgear

Analysis and implementation of zero-current breaking adaptive control
in intelligent AC contactor
ZHENG Xin, XU Zhi-hong, ZHANG Pei-ming
(College of Elec. Eng. & Automation of Fuzhou University, Fuzhou 350002, China)
Abstract：On the basis of research about intelligent AC contactor, this paper analyses the operational principle and difficult problems of zero-current breaking control technology to put forward a new scheme of adaptive control. The contactor realizes zero-current breaking control completely. The performance and the operating reliability of the intelligent AC contactor have been improved greatly. 
Key words: intelligent AC contactor; zero-current breaking control; adaptive control