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A proposal for strengthening energy work of The Chinese Academy of Sciences and improving its position in country’s energy development
YAN Lu-guang
(Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: Ensuring the energy supply is one of the most important conditions for human being subsistence and development. To establish a new energy sustainable development system in China, adjustment of energy structure in China is in progress. The Chinese Academy of Sciences has made important contribution to energy development in China. But it seems that its work in energy field proceeds rather slowly recently. To improve its position on Chinese energy development, several proposals were put forward. 0 Refs. In Chinese.
Key words: The Chinese Academy of Sciences; energy; status; proposal
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 1—6.
A proposal for planning and constructing a national integrated energy base combined with large-scale photo-voltaic power and hydropower in Qinghai province
YAN Lu-guang, ZHOU Xiao-xin, ZHANG Chu-han, et al.
(Chinese Academy of Sciences, Beijing 100864, China)
Key Words: Qinghai province; photo-voltaic power; hydropower; national integrative
Energy Base
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 7.
A power quality event data compression based on combined wavelet packets
ZHENG Wei-yan, WU Wei-lin
(College of Electrical Engineering, Zhejiang University, Hangzhou 310027, China)
Abstract: As the time-frequency characteristic of single wavelet base cannot match with complex signal feature, the compression effect could hardly be improved further in wavelet compression method, so this paper proposed combined wavelet packets based on wavelet packets algorithm for power quality signal compression. For different kinds of power quality data we using genetic algorithm search for the optimal combined wavelet packets base assemblage by using wavelet entropy function as cost function. The simulation results show that new algorithm gets better results when compare to the traditional wavelet and wavelet packet method at the same conditions. 14 Refs. In Chinese.
Key words: power quality; combined wavelet packets; entropy function; genetic algorithm
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 8—11.
Novel tapped-inductor bi-directional DC-DC converter and optimum design
XU Yu-zhen, GUO Xiao-jun, LIN Wei-ming
(College of Engineering and Automation, Fuzhou University, Fuzhou 350108, China)
Abstract: A novel tapped-inductor bi-directional (TI-B) DC-DC converters is analyzed in this paper, which can overcome the shortage of non-isolated bi-directional DC-DC (BDC) that its transfer ratio is restricted in a small range. This paper analyzes the principle and characteristics of TI-B-BUCK/BOOST in detail. Then, a power loss model of the new topology is established and the turn ratio of tapped-inductor is optimized. Simulation based on MATHCAD and the experiment on demo board testify that TI-B-BUCK/BOOST widely extends the transfer ratio of non-isolated BDC and its efficiency is much higher than conventional bi-directional BUCK/BOOST. 12 Refs. In Chinese.
Key words: bi-directional DC-DC converters; dissipation model; efficiency improvement; turn ratio optimization
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 12—15.
Research of a novel type electric power tower made in FRP
TANG Bo, WEN Yuan-fang, DENG Jian-gang
(1.College of Elec. & Electronic Eng., Huazhong University of Science and Technology, Wuhan 430074, China; 2.Wuhan High Voltage Research Institute of State Grid Electric Power Research Institute, Wuhan 430074, China)
Abstract: The electric power tower made of Fiber Reinforced Polymer (FRP) is researched in order to avoid many problems from current power tower. The present research status at home and abroad of FRP application used in power construction is introduced, and the FRP tower used in 110kV power transmission line is designed. According to the arrangement of conductors, FRP tower can be classified into two categories: inverted F type and ∏ type. Taking inverted F type tower as an example, the construction and dimension of FRP tower are designed, and the mechanical properties are analyzed to research the security intensity of possible failure modes. According to the theory of field decomposition, the unlimited three-dimensional field is divided into limited sub-fields, and the three-dimensional simulation models of usual tower and FRP tower are constructed to analyze the field strength on 1m-to-ground and the maximum field strength on the conductor surface. The result shows that the field strength of FRP is smaller than that of steel tower. Alternating the dimension of FPR tower, the mechanical properties and electric properties are analyzed, therefore, the minimum section width of tower is 37.6cm, the minimum pipe thickness is 3.06cm, and it suggested that the nominal height is 11m, the width of bottom cross arm is 4m.
Key words: power transmission line; FRP; mechanical strength; electrical strength; simulation; structure parameters
Improved power flow calculation of distribution network based on injection current imbalance
ZHU Hong-bo1, LIU Xin-wei1, SHAO Meng-meng1, JIA Jian-fu2, YANG Yan-liang1
(1. Northeast Dian Li University, Jilin 132012, China；
2. Training Center in Jilin Province Power Company, Changchun 130022, China）
Abstract: Based on the power flow calculation of distribution network of the node current-injection model, the injection current imbalance is adopted to improve and simplify the algorithm, to make Jacobian matrix a fixed matrix, and computation is greatly reduced and the computing speed is improved. An optimal factor is introduced to ensure the convergence of the computing process, and the sensitivity of the initial value about power flow calculation and some ill-conditioned systems problems are also resolved effectively. Using the distribution network of 30-node，141-node and several typical examples of ill-conditioned systems verify the effectiveness and feasibility of the method. 11 Refs. In Chinese.
Key words: distribution network; power flow calculation; notimal factor; ill-conditioned
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 22—25.
Virtual synchronous generator based inverter in microgrid
SU Jian-hui, WANG Chang-liang
(Research Center for Photovoltaic System Engineering Ministry of Education,
Hefei University of Technology, Hefei 230009, China)
Abstract: A new inverter based on the model of synchronous generator (which is called virtual synchronous generator) is presented. The inverter has the fuction of controlling power and modulating frequency and voltage, which meets the need of microgrid. It can modulate the output reasonably to meet the stability requirements of the power system. This scheme has been proved with MATLAB/Simulink in the end. 13 Refs. In Chinese.
Key words: microgrid; inverter; virtual synchronous generator
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 26—29.
Study of fault diagnosis system in rectifier units based on wavelet packet and fuzzy diagnosis
KUANG Yong-hong1, OUYANG Bo2, ZHOU Peng2
(1. Applied Technical College of Hunan Institute of Engineering, Xiangtan 411101, China;
2. School of Information Science and Engineering, Central South University, Changsha 410075, China）
Abstract: According to the cophase counter parallel connection rectifier units widespreadly used in the fields of power and chemical industry, the paper presents a wavelet packet - fuzzy recognition method with the three-phase current at rectifier transformer side as the diagnosis signal to realize fault diagnosis. Firstly, the fault eigenvalues are extracted with wavelet packet analysis to form a sample database, then the fuzzy recognition of sample status are identified by using J dispersion and maximum subjection principle. The method is verified by experiments, and the accuracy is excellent.
Key words: cophase counter parallel connection; fault diagnosis; wavelet packet analysis; fuzzy reasoning
An approach to improve efficiency of EV charger under light load
LI Jing-xin，NIU Li-yong，WANG Jian-qiang，JIANG Jiu-chun
(School of Electrical Engineering, Beijing Jiaotong University, Beijing 100044, China)
Abstract: This paper presented an approach to improve efficiency of EV batteries charger under light load. On the basis of analysis on the original charger built upon capacitor-diode-diode clamp circuit, a modified capacitor-diode-switching clamp circuit was designed to replace the original one in the full-bridge phase-shifted zero-voltage and zero-current-switching PWM DC/DC converter. Operating principle was introduced, and the critical condition to judge whether under light load was derived. Circuit simulation and experiment on the prototype were performed under different load. Both results show that besides the advantages of the original topology, higher efficiency and less stress on switches are achieved under light load. 6 Refs. In Chinese.
Key words: DC/DC converter; ZVZCS; full-bridge phase-shifted; circuit simulation
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 35—38.
Propagation stage characteristics of electrical tree in 110kV XLPE cable insulation at 50Hz power frequency voltage
CHEN Xiang-rong, XU Yang, XU Jie, SHI Wen, YANG Wen-hu, LIU Ying, CAO Xiao-long, LI Jin-fei
(State Key Laboratory of Power Equipment and Elec. Insulation, Xi’an Jiaotong University, Xi’an 710049, China)
Abstract: Based on the combined experimental methods of real-time microscope digital imaging technology and partial discharge continuous measurement, the structure properties and propagation characteristics of electrical tree in 110kV XLPE cable insulation were studied at different 50Hz power frequency applied voltage. Combined with a number of experimental results, it was found that under the effect of different applied voltages, the electrical tree structures displayed the features of diversity, the propagation process and partial discharge showed apparent stage characteristics, and also there were different propagation mechanisms in each stage.
Key words: power frequency 50Hz applied voltage; XLPE power cable insulation; electrical tree; stage characteristics; structure properties; partial discharge
Study of nonlinear model of three-winding autotransformer in ultra high voltage AC transmission system
YUE Hao, XU Yong-hai, LIU Ying-ying, ZHU Yong-qiang, XIAO Xiang-ning
(School of Electrical and Electronic Engineering, North China Electric Power University, Beijing 102206, China)
Abstract: Modeling of accurate nonlinear three-winding autotransformer is the basis of harmonic analysis of 1000kV AC transmission system. Based on the electromagnetic relations of single-phase three-winding autotransformer and the effect of excitation impedance, a new model of single-phase three-winding autotransformer used for harmonic analysis and computer simulation is presented. The nonlinear impedance is caculated by the and curves based on the magnetization curve and the no-load losses at rated frequency. The result of simulation in PSCAD/EMTDC using the parameters of transformers in China's Ultra High Voltage(UHV) AC Pilot Project have proved that this model accurately reflects the saturation characteristics of autotransformer, which is the prerequisite to complete the simulation model of UHV AC transmission system and to analyze the harmonic characteristic of the system. 9 Refs. In Chinese.
Key words: three-winding autotransformer; nonlinear model; ultra high voltage (UHV); harmonic characteristic
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 44—48.
Magnetic shielding of the gas-insulated transmission lines (GIL)
LUO Yao1, CHEN Bai-chao1, DING Jiang-feng2
(School of Electrical Engineering, Wuhan University, Wuhan 430072, China; School of Stomatology, Wuhan University, Wuhan 430079, China)
Abstract: The basic structure of the gas-insulated transmission lines (GIL) is introduced and their principles of magnetic shielding is analyzed. The analytical method is provided for all calculations, focusing on the explanation of the GIL shielding capability. The electromagnetic shielding of the cylindrical enclosure is analyzed by the Maxwell equations and shows the inability of its magnetic field shielding on internal conductor. Then, concerning the magnetic coupling of the GIL’s shell loop, its shielding mechanism is discussed. By these calculations, the principle of the enclosure induced current is explained, and the GIL’s superior characteristics of the electromagnetic environment is clearly shown.
Key words: GIL; eddy current density; magnetic field shielding; enclosure loop; magnetic coupling
Fault diagnosis technology based on Wigner-Ville distribution in power electronics circuit
WANG Rong-jie1,2, ZHAN Yi-ju3, GUO Ke-wei1, LIN Shi-xian1
(1.Marine Eng. Inst., Jimei University, Xiamen 361021, China; 2.School of Information Science and Tech., Sun Yat-sen University, Guangzhou 510006, China; 3.School of Eng., SunYat-sen University, Guangzhou 510006, China)
Abstract: A method of fault diagnosis for power electronics circuit was proposed based on Wigner-Ville distribution. At first, the standard module time-frequency matrices of Wigner-Ville distribution for all fault signals were constructed, then the similarity of fault signal’s module time-frequency matrices to standard module time-frequency matrices were calculated, and according to the principle of maximum similarity the faults were diagnosed. The simulation result of fault diagnosis of thyristor in three-phase full-bridge controlled rectifier shows that the method can accurately diagnose fault and locate fault element for power electronics circuit, and it has excellent performance on noise robust and calculation complexity, thus it is valuable for practical engineering in the solution to fault problem for power electronics circuit.
Key words: Wigner-Ville distribution; similarity; fault diagnosis; power electronics circuit
A power consumption rewards method considering electricity forecasting and competition factor
WU Fang-ci, LUO An, ZHAO Wei, JIANG Zhong-hua, MENG Jin-ling
(Hunan University, Changsha 410082, China)
Abstract：A power consumption rewards method for corporation, considering electricity forecasting and competition factor, is proposed in this paper. In this method, a grey dynamic model is used to accurately forecast the electricity consumption of corporation departments, then the results of the model are compared with real electricity consumption of each department. On the basis of the different energy-saving status, rewards coefficient is introduced to establish classification of rewards system. Besides, competition factor is introduced in order to give additional reward to the departments which make higher energy-saving benefits, resulting a competition mechanism among departments. Considering two aspects of comparison results, the final reward value is confirmed eventually. So that an advanced, effective and general corporation power consumption rewards model is built and the operation cost of corporation is decreased. The effect of application in a refinery proves the advantage and validity of this power consumption rewards method. Hence, it achieves the goal of reward foundation that providing energy saving and improving production efficiency for corporation.
Key words: power consumption rewards; grey forecasting; classification rewards; competition factor
Research progress of degradation mechanism of ZnO varistors
LIU Jun, HE Jin-liang, HU Jun, LONG Wang-cheng
(State Key Laboratory of Control and Simulation of Power System and Generation Equipment, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China)
Abstract: ZnO varistors played an important role in suppressing overvoltage of power systems, which directly determines the overvoltage level of power systems and the insulation level of apparatus. However, it is inevitable that the electrical property of ZnO varistor degrades as it is under long-term voltage stress or short-term impulse current stress. In this paper, different viewpoints and the latest development on the degradation mechanism of ZnO varistors proposed by domestic and abroad researchers in literatures were summarized and reviewed. In addition, the degradation mechanism was analyzed. Furthermore, methods of improving the stability of ZnO varistors were discussed.
Key words: ZnO varistors; degradation mechanism; ion migration; stability
Simulation and experimental research on electromagnetic buffer of electromagnetic actuator
GUO Feng-yi, LI Peng, LI Bin, WANG Zhi-yong, LI Chun-guang, WANG Ji-qiang, WANG Xi-li
(Liaoning Technical University, Huludao 125105, China）
Abstract: To compensate the shortcomings of spring buffer method, a kind of electromagnetic buffer control idea used for electromagnetic actuator on the course of closing processes was introduced. Applying a proper reverse exciting current to the buffer coil during the closing movement, a reverse force generated by the reverse current will decrease the inherent closing suction, therefore, can reduce the mechanical impact and achieve the function of closing buffer. By 3D vector analysis method with ANSYS software, the simulation calculation on closing suction characteristics of electromagnetic actuator under different conditions was carried out. Meanwhile, the contactor vibration curves were observed by a special experimental device. Preliminary studies have shown that the buffer current and its imposing position and imposing time have an important influence on suction characteristics. Only with comprehensive consideration of these three factors and selection of the appropriate control conditions, it is possible to get more satisfactory closing properties and buffer effects. The electromagnetic buffer control idea has certain significance of reference for other actuators to solve the existing closing impact problem. 10 Refs. In Chinese.
Key words: electromagnetic buffer; electromagnetic actuator; reverse excitation
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 68—71.
A digital control strategy for low-frequency square-wave electronic ballast for HID lamp
LIN Guo-qing
(College of Electrical Engineering& Automation, Fuzhou University, Fuzhou 350002, China)
Abstract: A low-frequency square-wave electronic ballast based on digital control is proposed to operate HID lamp in the paper. The discrete control is used to realize the matching of electronic ballasts and the dynamic characteristics of HID lamps, and its control method is detailed. By connecting HID lamp with the half-bridge MOSFET drain, the lamp voltage and current sampling circuit and the drive circuit of half-bridge converter share the same ground to make the control circuit be simply implemented. The experimental results have demonstrated that the proposed scheme has the advantages of simple structure, flexible control, smooth lamp stand-up process, constant power output, and no acoustic resonances. 7 Refs. In Chinese.
Key words: electronic ballast；low-frequency square-wave；digital control；HID lamps
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 72—75.
Implementation of solar LED lighting control system based on embedded target modules
CHEN Jian, ZHAO Zheng-ming, YUAN Li-qiang
(State Key Lab of Power Systems, Dept. of Elec. Eng., Tsinghua University, Beijing 100084, China)
Abstract: Solar LED lighting system as the new lighting technology has many advantages, such as green power usage, comfortable feeling and high efficiency. However, the complex and high performance control requirements challenged the control system, such as maximum power point tracking (MPPT) control, LED nonlinear load control and battery charging strategy selection. In this paper, the control system demands are analyzed. The MPPT control, battery charging strategy and LED load control research are achieved and simulations based on MATLAB/Simulink are accomplished. By using the simulation modules and eZdsp embedded target modules, the programs are generated for TMS320F2812 DSP’s control. High performance experiments are also achieved for the LED lighting system, such as fast dynamic response, smooth starting current and high precision for steady-state. This paper also set up an ideal control module for LED lighting system. The experimental programs generation based eZdsp provides an efficient realization for the DSP control system. 8 Refs. In Chinese.
Key words: embedded target modules; maximum power point track; LED lighting
// Adv. Tech. of Elec. Eng. & Energy, 2010, 29(3). 76—80.
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