Status of Xinjiang coal on energy development in China
YAN Lu-guang¹, ZHOU Feng-qi², HUANG Chang-gang¹
(1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
2. Energy Research Institute, National Development and Reform Commission, Beijing 100038, China)
Abstract: Sustainable energy development is a main task. Based on the recent studies, it is required that to change the primary energy structure with significant reduction of the fossil energy percentage and enhance the percentage of renewable, to establish the energy sustainable development system. Xinjiang is a region abundant in renewable energy and fossil energy. It’s status on Chinese energy development is very important. In this paper basic reserves, production and consumption of coal were described. The coal development in Xinjiang has to be changed from satisfying self-requirement to satisfying whole country requirement, and to be an important and integrated energy base progressively. Related suggestions were presented. 7 Refs. In Chinese.
Key words: coal; Xinjiang; energy; status
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 1—10.

Modeling of power transformer in wide frequency range and analysis of the impedance characteristic
YANG Yu, WANG Zan-ji, SHAO Chong
(State key Lab. of Power System, Dept. of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: In order to precise predict VFTO distributions in the windings during transformer design stage, the modeling of the power transformer winding in the wide frequency range is necessary. Applying multi-transmission line (MTL) theory to establish equivalent of the transformer winding and calculating its driving point impedance and voltage transfer functions, the natural frequencies and transient response can be obtained. The validity of the equivalent circuit can be verified by comparison of the calculated and measured impedance of a model winding. In this paper, the consistence of two MTL models developed on the systems of the circular cylindrical coordinates and the rectangular coordinates respectively for the core type transformer winding is firstly analyzed. Then the phase-modal transformation for MTL equations and the parameters of the  type equivalent circuit for MTL are developed. Finally, the driving-point impedance and the voltage transfer functions of the circuit are solved using node analysis. The measured impedance of a model winding verified that the equivalent circuit is valid for modeling of the transformer windings in the frequency range below 20 MHz. 10 Refs. In Chinese.
Key words: VFTO; power transformer; modeling; multi-transmission line; driving-point impedance
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 11—15.

Near field effect analysis and common mode conducted EMI model of a switched mode power supply
HE Jun-ping, ZHENG Bao-tang, WANG Yi
（Shenzhen Graduate School of Harbin Institute of Technology, Shenzhen 518055, China）
Abstract: In this paper, the electromagnetic near field coupling effects among a PFC power supply, an EMI filter and input power cord are studied by experiments and theoretical analysis in detail. Near field coupling nature and its influence positions are analyzed firstly. Then a Saber conducted EMI circuit simulation model of this power converter is built up and verified, which includes the electric coupling effect. After ignoring some small parameters in common mode EMI paths of this power supply, a simplified common mode EMI model is gotten and electric coupling influence is analyzed based on model. Critical sensitivity coupling distance concept is then proposed and applied between this PFC and EMI filter. Its value can be obtained by approximated calculation or measurement and it is helpful for power supply EMC optimizing design in early stage. Finally, some novel coupling EMI control methods, such as relative angle arrangement, are proposed and verified. 14 Refs. In Chinese.
Key words：switched-mode power supply; electric coupling; critical sensitivity coupling distance; common mode conducted EMI model
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 16—20.

Study on compound control strategy of hybrid active power filter with single injection branch
LUO An, SHU Shi, SUN Xian-da, SHUAI Zhi-kang
 (Hunan University, Changsha 410082, China)
Abstract: In this paper an electrical model of the shunt hybrid active power filter with injection branch (SIBAPF) was built. Two control strategies for hybrid active power filter are compared according to this model, and then a novel control strategy based on the detection of harmonic voltage and harmonic current of the grid was proposed. Meanwhile, the performance of harmonic current compensation and its influence on suppressing variation of frequency and impendence of the system when the proposed strategy is adopted is analyzed. In order to improve the dynamic performance of the system and realize no error control, a complex controller based on recursive integral PI control is proposed. And the parameters of the controller are on-line tuned by fuzzy inference to enhance self-adaptive ability of the system. Simulation and experimental results show that the SIBAPF can reach an ideal filter effect when the proposed novel control strategy is adopted. 10 Refs. In Chinese.
Key words: harmonic elimination; active power filter; complex control; recursive integral control
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 21—24.

Research on high-voltage test equipment based on effect of space electric field
TANG Ning-ping¹, ROU Shao-yu², LIAO Fu-wang²
(1.Fuzhou University, Fuzhou 350002, China; 2.Fujian Electric Power Test & Research Institute, Fuzhou 350007, China)
Abstract: On the basis of the calculation and analysis of electric field of a new type of capacitive divider based on the effect of space electric field, some problems are discussed in the paper such as the relation between the capacitive divider hanging site and the distribution capacity to ground, the distribution maps of the electric field for the elliptical and the orbicular high-voltage probe, the minimum radius of the capacitive divider under different voltage. The structure and parameter of the divider are designed. As the application of the capacitive divider, a high-voltage test equipment is made. The experiment results show the equipment has good characteristics such as measurement precision, frequency response and waveform fidelity and can apply to the site-test of high-voltage equipments in power system. 9 Refs. In Chinese.　
Key words: effect of space electric field; capacitive divider; high-voltage test
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 25—28.

Reliability assessment of protective relaying based on operation risk theory
WANG Qing-liang，HOU Yuan-bin，FU Zhou-xing，LI Zhong
(Xi’an University of Science and Technology，Xi’an 710054，China)
Abstract: Based on the risk theory, a new reliability index is proposed considering correct inaction, failure events and the failure probability of protected equipment in protective relays. The economical losses resulted from failure events are taken into consideration in the method. A general 8-state Markov probability model of line protection is set up in which resist-operation failures are divided into extended state and no-extended state. Using the state space method, the reliability indices have been calculated. Studies have been conducted to ascertain the relation between the protection reliability and failure probability of equipment involving the economical loss of incorrect operation. Then, the optimal maintenance interval is derived by taking the minimum of risk assessments as target function for protective relays. The obtained interval is significant to predict the protection maintenance. The general and detailed reliability model with its algorithm was validated with the protective relays test. It proves a new idea and method to improve protection system and they can enhance the security of distribution power supply. 8 Refs. In Chinese.
Key words: protective relay; reliability; failure event; risk assessment; correct inaction; state space method 
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 29—33.

Influence of temperature on partial discharge properties in disc-void of oil/pressboard insulation
LI Jun-hao, SI Wen-rong, YAO Xiu, GUO Zhi-feng, LI Yan-ming
(State Key Lab of Elec. Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Partial discharge based risk assessment method has rapidly developed as an effective diagnose method in oil/pressboard insulation system. The temperature in field power transformer is variable according to loading and the PD properties in insulation also variable in differently temperature. In order to assess the influence of temperature on partial discharge properties in oil/pressboard insulation system, a partial discharge testing system with temperature adjusting function was adopted in this paper. The partial discharge data obtained from the experimental work was presented in phase-resolved PD(PRPD) pattern analysis、pulse sequence analysis(PSA). The single pulse in time domain in differently temperature is also analysis in this paper. 12 Refs. In English.
Key words: partial discharge; oil/pressboard insulation; temperature; pulse sequence analysis
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 34—37.

Influence of damper winding on voltage waveform of loaded salient pole single phase synchronous generators
YANG Jing , WANG Wei-jun , TU Ya-qing , ZUO Yong-gang
(1. Dept. of Barracks’ Management and Environment Engineering; 2. Dept. of Logistical Information Engineering; 3. Dept. of Military Petroleum Supply, Logistic Engineering University, Chongqing 400016, China)
Abstract: The small salient pole single phase synchronous generators (SSPSPSG) are used widely as standby power supply, but they have heavy harmonic distortion in their voltage waveform with load. The damper winding can weaken the negative sequence magnetic field in SSPSPSG with load and decrease the voltage harmonic distortion. In this article, time-stepping finite element method coupling with circuit is programmed and used to compute the output voltage of the SSPSPSG on rated load. The results of computation are consistent with the tests, which show that the computation method and program are both correct. The voltage waveform of SSPSPSG with different connection manners and different materials of damper winding are analyzed in detail. The conclusion can provide theoretical guide for selecting connection manner and material of damper winding and lead to the improvement of voltage waveform.
Key word: salient pole single phase synchronous generator; damper winding; voltage waveform; time-stepping finite element method coupling with circuit

Research and application on Preisach hysteresis model based on ANN
HUANG Ping-lin^{1, 2}, HU Qian-sheng²
（1. Yichang Testing Technique Research Institute，Yichang 443003, China；
2. Electrical Engineering school of Southeast University, Nanjing 212013, China）
Abstract：Based on the static Preisach hysteresis model, the technology of ANN is applied to calculate the hysteresis loop under alternating magnetization considering the symmetry of the major hysteresis loop. Adopting this method one sample’s hysteresis loop is calculated. For hysteresis loop measurement, a new approach is proposed using the Epstein frame, this approach is suitable for practical engineering applications, and the results of the measure verify the theory.
Key words: ANN; Preisach hysteresis model; hysteresis loop; Epstein frame

Compensation strategy of dynamic voltage restorer with flywheel energy storage
ZHU Jun-xing, JIANG Xin-jian, HUANG Li-pei
(State Key Lab of Security Control and Simulation of Power Systems and Large Scale Generation Equipments,
Department of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: In view of the shortcomings of traditional Dynamic Voltage Restorer (DVR) without energy storage devices, a DVR is developed using flywheel energy storage (FES). The circuit topology and basic principles of the system are described. The compensation strategies are compared based on the characters of the FES, and the synthetic compensation strategy not only considers the maximum voltage injection but also optimizes the energy exchange process between the DVR and the power system, thus the compensating time is increased. Since the computation of the phase angle α is complex and the backward of energy is neglected in the conventional synthetic compensation strategy, a new method for determining α is proposed according to the analysis of the PDVR-α and SDVR-α curves. Simulation results verify the effectiveness of the compensation strategy and the method for determining α.
Key words: dynamic voltage restorer (DVR); flywheel energy storage (FES); voltage sag; synthetic compensation strategy

Simulation study of E-M wave transmission characteristic in straight and L-shaped tanks of GIS structure
YANG Jing-gang, LI Da-jian, LI Jun-hao, SI Wen-rong, LI Yan-ming
(School of Electrical Engineering, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Propagation characteristic of electromagnetic wave which is excited by partial discharge in GIS is simulated based on the method of FDTD. The transmission characteristics of TEM and TE, and reflected wave which is generated by L-shaped tanks are analyzed in the straight and L-shaped tanks of GIS structure, through setting the different directions of electromagnetic, and comparing the time and frequency domain results of electromagnetic wave in different structures and measurement angles. There are some factors that influence E-M Wave Transmission Characteristic, such as directions of electromagnetic, wave velocity dispersion and wave mode transformation.
Key words：partial discharge; E-M wave; FDTD; GIS

Magnetic and loss characteristics of inclined joint iron core based on dual-laminated-core model
ZHANG Xian¹, XING Jin¹, YANG Qing-xin¹, CHEN Hai-yan¹, CHENG Zhi-guang², DU Yong¹, HU Qi-fan², ZHANG Jun-jie², LIU Lan-rong², JIAO Cui-ping² 
(1. Hebei University of Technology, Tianjin 300130, China; 2. R & D Center, BTW Group, Baoding 071056, China)
Abstract: Dual-laminated-core model, i.e. two laminated iron cores have the same joint type and are made of the same material but different length of limbs, is established for simulating the working conditions of power transformers. The exciting power at joints is separated in way of material homogenizing. The magnetic and loss characteristics of the model cores, without stress relief annealing, are measured for comparison with the results by Epstein. Results in this paper have been adopted to [1] and the accuracy satisfies engineering requirement. The way to determinate the average magnetic circuit length is discussed for reducing error, including which type of B-H curves should be chosen for FEM simulation.
Key words: dual core model; over saturation; joints; exciting power; laminated core

Study on the design of emergency-response system of urban power grid and Shenzhen joint exercise plan against large scale of blackout
LI Rui, LIU Dong, CHEN Ying, MEI Sheng-wei
(Department of Electrical Engineering, Tsinghua University, Beijing 100084, China)
 
Abstract: The blackout in a large area can bring big loss to national economy. A scheme of the architecture of emergency-response system for urban power grid is proposed, including the emergency-response management system and the emergency-response support platform. The management system defines the organization, running mechanism and resources. The platform provides automatic and intelligent support according to the management system for personnel involved in emergency-response. The problem that how to test the integrality, the rationality and efficiency of emergency-response system by joint exercise is investigated. The factors that involved in joint exercise planning are analyzed. The goal, style, content and evaluation method of joint exercise are presented. The indices of evaluation of joint exercise include security, integrality, comparability with reality, economy and pertinency. A practial case of Shenzhen city is illustrated to demonstrate the validity of the proposed emergency-response system and the effect of joint exercise againt large scale of blackout. 19 Refs. In Chinese.
Key words: urban power grid；large area blackout；the construction of emergency-response system；joint exercise
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 61—65.

Experimental research of AC breakdown voltage of evaporative coolant
under boiled two-phase-flow condition
NIU Wen-hao¹,  ZHANG  Guo-qiang¹,  WANG  Xin¹，XU Zi-hong²，SHANGGUAN Yuan-ding3
(1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;  2. China Elec. Equipment Group, Nanjing 211100, China; 3. Jiangxi Transformer Science&Technology Co.,Ltd,  Nanchang 330114, China)
Abstract: As some fluorocarbons have the nonflammability and high electrical strength, they could be used not only as coolant, but also as insulating materials in evaporative cooling transformers and other electrical apparatuses, which will make transformers be nonflammable and non-explosive, safe and reliable, economical and efficient, environmental friendly. In order to obtain the AC breakdown voltage of evaporative coolant under boiled two-phase-flow condition, where the fluorocarbons in application are used as insulating materials, a special experimental equipment was designed and fabricated according to the related national standards. Using a plane-plane electrode with a gap length of 3 mm, the test was carried out in conditions under different pressures. The statistical analysis of the data demonstrated that both of the Weibull and Normal distribution match the result quite well, and provided probability distributions of the breakdown voltage under corresponding pressures. The result also offered plotted relation curve of the breakdown voltage with working pressure of boiled two-phase-flow condition, which is important reference to the insulation structural design of the evaporative cooling transformer.
Key words: fluorocarbon; evaporative cooling; two-phase-flow; transformer; breakdown voltage; Weibull distribution; normal distribution

A novel design for fuel cell inverter system
ZHANG Yi, CHEN Guo-cheng, WU Chun-hua, CHEN Wei-min, CUI Kai-yong, ZHU Yi-bo
(Shanghai Key Lab of Power Station Automation Technology (Shanghai University), Shanghai 200072, China)
Abstract: The paper proposed a standalone inverter used for single-phase emergency power supply, which achieved the whole processes of the inverter on the same equipment. The inverter includes the FC launching, rated operation, system detection and error protection, etc. The proposed Fuel Cell inverter consists of start circuit of Fuel Cell, the front-end dc-dc converter, the dc-ac inverter and the Buck converter. Finally, the practical system testing indicates the inverter operation stably and has good performance. 13 Refs. In Chinese.
Key words: fuel cell; single-phase power supply system; inverter
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 71—75.

Research on improved modulation strategy of cells cascaded multi-level converter
LONG Qing-wen, OUYANG Hong-lin, ZHU Si-guo, DING Wei
(College of Electrical & Information Engineering, Hunan University, ChangSha 410082, China)
Abstract: The topologies and work principle of carrier phase shift control of cells cascaded multi-level converter are introduced simply in this paper. According to its advantages and disadvantages, a new improved PWM modulation strategy is presented, which is suitable for cascade multilevel converters. Then, the paper presents its principle and gives the method of system realization. The building of system module and simulating of this method were done by MATLAB software. The simulation results show that this strategy has the better control effect compared to the carrier phase shift control. Based on cells cascaded high-voltage converter, numeric control of the system was realized using TMS320F2812, FPGA and PLC. The experimental results demonstrate the feasibility of this new method. 9 Refs. In Chinese.
Key words：carrier phase shift control; modulation strategy; system realizatio
 // Adv. Tech. of Elec. Eng. & Energy, 2009, 28(1). 76—80.