Abstracts of Vol.23, Issue 1, 2004

Suggestion for scientific comparison and selection
of the Beijing-Shanghai high-speed line option
YAN Lu-guang
(Institute of Electrical Engineering, Academic Sinica, Beijing 100080, China)
Abstract: Following the important opinion of the central government leader: “Concerning the construction of the Beijing-Shanghai high-speed railway, it is necessary to hear widely different opinions, conduct fully discussion and scientific comparison and selection, and provide suggestion”, we took part recently in related discussions organized by National Development and Reform Committee and China International Engineering Consultation Company, the present paper summarized our suggestion to conduct scientific comparison and selection work in the near future.
Key words: Beijing-Shanghai high-speed line; scientific comparison; option selection

Study of the bypass switching strategy and phase lock loop technique
for fully digital-controlled UPS
DUAN Shan-xu, XIONG Jian, KANG Yong, CHEN Jian
(College of Electrical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China)
Abstract：Uninterruptible Power Supply (UPS) has been applied in many fields. The designing purpose of UPS is introduced in this paper. Based on the analysis of some pivotal techniques for UPS, a novel scheme of fully digitized control system based on DSP (TMS320F240) is proposed. The principle and performance of phase lock loop are especially analyzed and the method used for fast voltage detection is presented for the digital-controlled UPS, which are used for supplying the load uninterruptedly. These methods are very simple and practical. The experimental results demonstrated that the practical system could achieve good dynamic and state performances.
Key words：UPS；phase lock loop；voltage fast detection；bypass-switching control

A novel space vector PWM method for six-phase induction machines
HOU Li-jun1,  SU Yan-min1,  CHEN Lin2
(1. Xi’an Jiaotong University, Xi’an 710049, China；
 2. Wuhan University of Science and Technology, Wuhan 430074, China)
Abstract: Based on the classical space vector theory and unified voltage modulation technique of three-phase drives, a novel space vector PWM scheme of six-phase induction machine drives is described in this paper. This modulation strategy not only effectively suppresses the large stator harmonic current in a six-phase induction machine fed by voltage source inverter and improves utilization of the dc-bus voltage, but also is realized easily and implemented quickly. In addition, the method developed in this paper be easily generalized the control of an induction machine with an arbitrary number of three-phase winding sets. As well as giving a detailed explanation of the presented algorithm, the paper performs a complete analysis and a comparative study between the proposed strategy and the conventional method such as the SVPWM and sinusoidal PWM for six-phase induction machine drives. Finally, simulation results and experimental tests have been carried out to validate the proposed strategy which gives satisfactory results in terms of current harmonic minimization and low implement complexity. In particular, it has great practical prospect on the implement of multiphase PWM schemes.
Key words: six-phase induction machine; voltage source inverter; space vector PWM; unified voltage modulation

Research on H∞ non-fragile robust decoupling and control
for a gasifier control system of a IGCC power plant
HENG Qing-hai
( Beijing Information Technology Institute，Beijing 100101，China )
Abstract：A gasifier in a IGCC power plant contains model uncertainties as time-delay, parameters, etc. The realizations of controllers (include actuators) can’t be quite accuracy. The design concepts of the non-fragile robust performance of the system with the perturbations of the controlled members and the controllers are presented. It can be used to solve the non-fragile robustness problems of the gasifier control system, which can’t be done by the conventional (including normal robust performance) designs. Because the steam hardly influences head value and the disturbance concept of robust control is employed, the concept of robust decoupling is presented. It is also suggested that the design of the non-fragile robust performance can be formulated as a H∞ mixed sensitivity problem about two SISO systems to the gasifier as a MIMO system if the uncertainty weighting function and the performance weighting function are revised appropriately. The selections of the weighting functions are studied and the H∞ non-fragile robust PI controllers are solved. The simulation results show that the proposed method is valid.
Key words：gasifier control system；perturbed controller；non-fragile robust performance；robust decoupling；H∞ control

Application of rough set to build transformer fault diagnosis model
based on multivariate decision tree
WANG Nan，LU Fang-cheng，LI He-ming
(North China Electric Power University, Baoding 071003, China)
Abstract: Through decision tree to build the model of transformer fault diagnosis, not only fault samples with nonnumerical values can be processed, but also rules can be learned and knowledge can be simplified with better adaptive capability. However, there exists certain limitation to describe complex cause and reason relationships through univariate decision tree, in which any symptom may be detected repeatedly along one path. In this paper, transformer fault diagnosis approach based on multivariate decision tree is presented. To improve analytical efficiency, several symptoms can be detected synchronously in one node of the multivariate decision tree. Based on advantages of rough set, such as knowledge reduction and classification, through discernibility matrix of rough set to select symptoms and construct multivariate decision tree for transformer fault diagnosis, the diagnosis knowledge can be reduced. And the diagnosis model is visual and easy to understand. Results of comparison test verify the effectiveness of the approach.
Key words: transformer; fault diagnosis; multivariate decision tree; rough set

Control system of the multiple large power rate active power filter
LI Hong-yu, ZHUO Fang, LEI Wan-jun, WU Long-hui, WANG Zhao-an
（Xi’an Jiaotong University, Xi’an 710049, China）
Abstract: First, the configuration and operation principle of the large power rate active power filter with multiple PWM converters are introduced and analyzed. Second, according to the control purpose, the digital-analog hybrid control system based on dual DSP is presented, and the configuration of control system and the flow chart of software are introduced. The synchronization of current conference and net voltage is well achieved by adopting the combination of hardware phase lock loop and software phase lock loop. Software is programmed specially in order to solve the problems of applying active power filter，such as adopting different filters according to various compensation purposes and adopting different PI conditioner according to the process of active power filter. Finally, the experimental results of the active power filter adopting the proposed control system are given. It shows that the compensation properties of the active power filter are very good.
Key words: multiple; large power rate active power filter; digital-analog hybrid control system; hardware phase lock loop; software phase lock loop

The Model of electricity demand curve and its applications
Huang Yonghao1, Kang Chongqing1, Li Hui1, Xia Qing1, Wang Gongli2, Hu Zuohao3
(1,3. Tsinghua University, Beijing, 100084, China;
2. Jixi Power Bureau, Jixi, 158100, China)
Abstract: Electricity Demands of consumers are not fixed according to the theory of microeconomics. Electricity price is one of the most important factors affecting electricity demand. From the data of consumer’s price survey, the model of Electricity Demand Curve (EDC) is established in this paper. Least Square Method is adopted as the approach of parameter estimation to calculate the parameters in the model. Based on EDC, the price elasticity of electricity demand is analyzed to show the sensitivity to electricity price. Furthermore, a quantitative analysis is given to the well-known strategy of increasing demand by depreciating. The results show that some strategies based on this idea will be invalidated under certain conditions. This leads to an approach of pricing for different consumers according to their EDCs which is useful for the electrical power enterprise to set reasonable marketing strategy. Numerical case studies show that optimal pricing for different consumers is possible and reasonable.
Key words: electricity demand curve (EDC), marketing, pricing strategy

Iterative generalized integrator algorithm based ternary variable structure control for active power filter
TU Chun-ming, LUO An
(College of Information Science & Engineering, Central South University, Changsha 410083, China)
Abstract: An iterative generalized integrator algorithm is proposed to eliminate steady error in active power filter. With introducing results of the algorithm into sliding-mode variable control law as its equivalent control, a novel ternary variable structure control is founded. Both fast response and satisfying control accuracy are achieved and proved by simulation results.
Key words: active power filter; generalized integrator; variable structure control

Self-excited single phase induction generator
with self-regulation by series capacitor
SUN Yu-ping, LI Guang-you, ZHANG Ji
(Electrical Engineering Institute of Shandong University, Jinan 250061，China)
Abstract: In view of large variation of output voltage of self-excited single phase induction generator, the paper presents an approach of self-regulation of voltage by series capacitor. The operation of self-excited single phase generation of three phase induction generator is analyzed by symmetrical component method, and the fundamental equations and equivalent circuit are derived. Then the formula for calculation of the generator performance and principle of selection of capacitors are given. The experiments of a sample generator verify the validity of the analysis.
Key words: induction generator；single-phase operation；self-excitation by capacitor

Optimal design of permanent magnetic actuator
based on dynamic behavior analysis
YOU Yi- min, CHEN De-gui, SUN Zhi-qiang, ZHANG Jing-shu
(School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: A set of software is developed for analyzing the dynamic behavior of permanent magnetic actuator, calculating magnetic field with Finite Element Method and coupling with equations of the mechanical motion and circuit. The dynamic behavior of actuator is simulated and verified by the experimental results. The concept of none-working air gap δis proposed. A research on the effects of δ,capacitor, coil and power supply on the switching current and velocity is carried out. The calculation result of this software is verified by the test result, the divergence of the average closing velocity is 4%. The non-working gap influences not only current of the starting operation of the circuit breaker but also the characteristic of switching speed of circuit breaker. The dimension of non-working gap can be optimized by the calculation of the dynamic characteristic of the permanent magnet mechanism. It can optimize the structure of the permanent magnet actuator and provide guidance for the engineering design. The parameters of the coil are also an important part in the designing of the permanent magnet mechanism, the stroke of the circuit breaker and the current of the coil are influenced by the diameter of the wire, number of turns and the resistance of the coil. From the view of saving power and reducing external dimensions, optimal parameters can be selected.
Key words: permanent magnet actuator; dynamic analysis; optimized design

Research of optical fiber displacement sensor based on data fusion theory

SHI De-gang, LIU Ye, WEI Zhao-bi, ZHANG Guo-lin, HU Guang-hui, WANG Cai-tang
(School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: A new method to solve optical fiber displacement sensor's cross-sensitivity problem introduced by temperature is presented, which is based on the theory of multi-sensor data fusion. To reduce coefficient of cross-sensitivity, in this method, a digital temperature sensor is added, outputs of displacement sensor and temperature sensor are fused, and compensation through software is introduced. The experiment shows that coefficient of temperature sensitivity of the optical fiber displacement sensor is reduced to one third of what it was. In addition, both accuracy of measurement and stability of the system are improved. A new idea for utility design of sensors with cross-sensitivity is proposed.
Key words: optical fiber displacement sensor; multi-sensor data fusion; cross-sensitivity

Study on a novel single-phase parallel hybrid power filter
DUAN Yong, WANG Yue, FU Zhi-ping, YANG Jun, WANG Zhao-an
(Xi’an Jiaotong University, Xi’an 710049, China)
Abstract：A novel single-phase parallel hybrid power filter is presented in this paper, which can eliminate drawbacks of LC passive filter and the conventional voltage source parallel hybrid power filter. The novel power filter consists of the well tuned LC passive filter, the additional inductor and the active power filter（APF）which is controlled as a harmonic current source . According to the theoretic analysis, a formula estimating VA rating of APF and some design principles of the additional inductor are proposed. Simulation and experiment results verify the effectiveness and advantage of the novel power filter.
Key words：hybrid power filter; additional inductor; harmonic current source

Power resonant converter and its development trend
ZHU Jian-hua, LUO Fang-lin
(Nanyang Technological University, Singapore, 639798)
Abstract: This article summarizes latest research progress in the development of power resonant converter. The topologies, characteristics and basic operating principles are given in detail. Three resonant converters, i.e. SRC, PRC and SPRC are discussed as the typical topologies and the relevant applications are also involved. In addition, the operating behavior under leading mode and lagging mode is stated. It is suggested that the converter be preferred to operate in the leading mode since it obtains more advantages over the counterpart. As for the control scheme, the principles of variable-frequency control and phase-shift control are presented. Finally, the development tendency of power resonant converter is also prospected.
Key words: power resonant converter; soft-switching technique

Fuzzy logic based high voltage transmission line fault type recognition
JIANG Hui-lan , LIANG Zhao-jun , YANG Wei , Xu Jian-qiang
(1. Tianjin University, Tianjin 300072, China;
2. Daqing Oil Field Management Board, Daqing 163000, China)
Abstract: On the basis of analyzing the high-voltage transmission line fault type recognition principles and implementation methods, this paper taking advantage of the superiority that fuzzy set theory is suitable for solving the problem with uncertainty information or uncertainty linear division relations, presents a new method of identifying high voltage transmission line fault type with hierarchical structure characteristic. The simulation results have shown that the proposed method can recognize fault types correctly and is suitable to the non-linear divisible case appeared possibly in fault pattern space, and to any kind of the transmission line system model structure as well, and therefore its generality and practicability can be ensured.
Key words: transmission line; fault type; fuzzy logic; artificial intelligent

Calculation of synchronous reactance for rare earth permanent magnetic motor
using electromotive_force method
LIN Rong-wen, JIANG Hui
(Fuzhou University, Fuzhou 350002, China)
Abstract: The paper analyses the distribution of magnetic field in the permanent magnet synchronous motor with rated power of 800W. On the basis of the traditional approach to calculating armature reactance, we put forward a new method which is based on the calculation of the electromotive_ force equation, and name it after “electromotive _force method”. Moreover, we determine the reactances of the experimental motor by the way of direct _load method, and verify the validity of “electromotive_ force method ”.
Key words: permanent magnet motor; finite element electromotive_force method

Calculation of reactance characteristic of dry-type half-iron-core reactors
ZHAO Yan-zhen, MA Xi-kui
(School of Electrical Engineering, Xi'an Jiaotong University, Xi’an 710049, China)
Abstract: In this paper the reactance characteristic of a new kind of reactor-dry type half-iron-core reactor is calculated with electromagnetic field numerical method. First, the time-stepped finite element numerical calculation model of the 3D time-varying electromagnetic field of the reactor is set up using field-circuit coupling method, by solving the model, the non-sinusoidal periodic current through the reactor is obtained under the sinusoidal voltage source. Then, with Fourier Transform the current is decomposed to different frequency components. Last, the V-A and harmonic characteristic of the reactor is obtained. The method proposed is applied to actual analysis and calculation. By comparing the results of the calculations with the experimental results, the method is proved to be correct and effective.
Key words: field-circuit coupling; half-iron-core reactor; reactance characteristic

A digital relay software platform based on µC/OS-Ⅱ
WANG Jing, YAO Jian-jun, WANG Jian-hua
(Dept. of Elec. Eng , Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: The vast use of multifunction digital relays with incompatibility; their fast speed of refurbishment and the ever-higher requirements of power system protection lead to the implementation of the general-purpose digital relay software platform of power system protection based on RTOS. According to the function analysis of the power system protection, the task assignment and the task schedule strategy of the software platform are determined based on the chosen RTOS, µC/OS-Ⅱ, which is capable of achieving the desired reliability and fulfilling the critical time requirement because of its constant and deterministic execution time. A power line protection device is developed with the help of the software platform. Because it is general-purpose, easily portable and extendable, the digital relay software platform based on µC/OS-Ⅱ has paved the way for the realization of configurable digital relays.
Key words: digital relay; software platform; embedded system; RTOS

Study and design of control system
of negative high-voltage pulse power supply for ECRH
DU Shao-wu1, ZHANG Chong-wei1, DING Tong-hai2, XU Ning1, LIU Bao-hua2
（1.School of Elec. and Automatic Eng.，Hefei University of Technology, Hefei 230009, China; 2.Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, China）
Abstract: High-voltage power supply (HVPS) is one of the most important components in ECRH (Electron Cyclotron Resonance Heating). It is the power supply of the gyrotron, which generate microwave to heat the plasma in TOKAMAK. The composing and principle of high-voltage power supply is analyzed in this paper. The circuit of every links of the system, include the main circuit, grid drive circuit, pulse gate circuit et al, and a new PI adjuster with forward feed-in are designed. Parameters of adjuster are fixed based on MATLAB simulation. The experiment based on the parameters shows better characteristics.
Key words: ECRH; high-voltage power supply; tetrode; grid drive