|
Great promotion of development of large scale integrative energy base in Xinjiang
YAN Lu-guang, XIA Xun-cheng, LV Shao-qin, WU Jia-chun, LIN Min, HUANG Chang-gang
(Academic Divisions of Chinese Academy of Sciences, Beijing 100864, China)
Abstract: Xinjiang is affluent in energy resources and occupies a special geography position. It has an important stratagic meaning on energy repertory, energy supply, energy security and energy channels. In this paper the main content of development of integrative energy base, its constructing supposition, also main suggestion to push development of large scale integrative energy base in Xinjiang were described.
Key words: Xinjiang; sustainable energy; integrative energy base
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, FEI Wei-yang, XIA Xun-cheng, ZHOU Feng-qi, HU Xue-hao, XU Hong-hua, HUANG Chang-gang, LIU Feng-song, WANG Shu, MA Ji-ming, WANG Bao-guo, PENG Yan-chang
(Academic Divisions of Chinese Academy of Sciences, Beijing 100864, China)
Abstract: Academic Divisions of the Chinese Academy of Sciences have organized relative academicians and experts to accomplish a study about synthesized energy base combining large scale photo-voltaic power generation and hydro-power in Qinghai province. In this paper the significance of synthesized energy base combining large scale PV power generation and hydro-power were discussed. The existing groundwork and special meaning of planning and constructing synthesized energy base in Qinghai province were indicated. The facing problems and measures which have to be taken into action were pointed out also. 3 Refs. In Chinese.
Key words: Qinghai province; photo-voltaic power generation; hydro-power; national synthesized energy base
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 8—11.
Sensorless vector control for PMSM to fans or water pump
WU Chun-hua1, HUANG Jian-ming1, LIU Jun2
(1. Shanghai Key Laboratory of Power Station Automation Technology, Shanghai University, Shanghai 200072, China; 2. School of Elec. Eng., Shanghai DianJi University, Shanghai 200240; China)
Abstract: This paper presents a strategy for rotor position and speed estimation at low-speed by establishment of electrical steady-state observer for PMSM. Consequently, starting process of PMSM is accomplished successfully. The back-EMF state observer is designed under high-speed condition, and the rotor speed and position can be estimated by error-tracking controller. This method can achieve effective and stable starting, simple algorithm, small starting current and high reliability. Finally experimental results proved the correctness and validity of the method. 10 Refs. In Chinese.
Key words: electrical steady-state observer; full-order state observer; sensorless; starting; PMSM
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 12—15.
Selections of nominal plant and weighting functions
of multi-model superheated steam temperature robust control system
HENG Qing-hai
(Beijing Information Science and Technology University, Beijing 100192, China）
Abstract：This paper presents the H∞ robust control problem of the perturbed model of the leading and inertia sections of the superheater of a supercritical concurrent 600MW boiler. The drastic change of the model parameters (including time constant, gain, even the orders etc.) of the controlled member occurs as the operating conditions are changed drastically. A design method of H∞ robust PID control system is proposed, and the selections of nominal plant and weighting functions of the multi-model robust control system are discussed and the H∞ robust PI controllers are solved. Results of the design look as if they were normal PI controllers, but their control quality, robustness and adaptability are better than the latter, and their structures are simple, definite, useful, etc. The realization of the controllers doesn’t involve extra cost to the control equipment in existence. The results show that the proposed method is valid.
Key words：multi-model perturbation; superheated steam temperature; robust control
A novel soft-switching control strategy for Buck converter
LIN Guo-qing，CHEN Zhi-jian，HE Xin-song
(College of Electrical Engineering& Automation, Fuzhou University, Fuzhou 350002, China)
Abstract: The operation principles and the condition of soft-switching of the zero-voltage quasi-square-wave Buck converter are analyzed in detail in the paper. A novel soft-switching control strategy，in which the turn-off moment of the auxiliary switch is controlled by the negative inductor current and the turn-off moment of the main switch is controlled by the positive inductor current，is proposed to realize the zero-voltage soft-switching for the main switch and auxiliary switch under wide output voltage and load current range. Some experimental measurements have been done through its application to the electronic ballast for 150W MH lamp. The simulation and experimental results show that the proposed converter has such advantages as wide soft-switching range, less switching losses, higher efficiency and reliability, etc. 7 Refs. In Chinese.
Key words: zero-voltage quasi-square-wave；buck converter；soft switching；control strategy
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 20—23.
Rapid leakage identification of coal mine low voltage distribution network based on signal distance degree
ZHAO Jian-wen, HOU Yuan-bin
(School of Electrical and Control Engineering, Xi’an University of Science and Technology, Xi’an 710054, China)
Abstract: The existed leakage judging method of coal mine low voltage distribution network has the disadvantages of large error and long action time, so it is unfavorable for safety operation. The characteristics of transient zero voltage occurring at leakage are analyzed; signal distance degree and signal matching degree are defined, which can be used to express difference of signal waveforms; and by adopting wave form difference of tansient zero sequence voltages between pre-leakage and after-leakage, a novel coal mine leakage identification method based on transient zero sequence voltage fault distance is put forward. Through adding the fluctuation factor, the leakage identification result is more linear with leakage resistance, and the influenc of system voltage fluctuation can be avoided effectively, and makes the leakage threshold value to have adaptability system. From simulation for a 660V coal mine distribution network, we know that this leakage identification method is more accurate and more rapid; and the algorithm time is about of a half cycle. 8 Refs. In Chinese.
Key words: coal mine leakage; signal distance degree; transient zero sequence voltage; rapidity; reliability
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 24—27.
Thermal equilibrium control of natural soft-switching two-level DC/AC inverter
CHEN Jian-ming1, WU Wei-min1, GENG Pan1，YE Yin-zhong2
(1. The Research Institute of Electronic Automation of Shanghai Maritime University, Shanghai 200135, China;
(2. Shanghai Institute of Technology, Shanghai 200235, China)
Abstract: In this paper, a natural soft-switching inverter is introduced, which can integrate DC/DC and DC/AC two stages power conversion. During the special shoot-through Zero states, the switching process is analyzed in detail, which reveals that the thermal unbalance of inverter will occur due to the unchanged saw-tooth wave carrier. Based on this fact, a new optimize control strategy is proposed making the switches of the inverter operate in the state of thermal balance. Experimental results are presented to verify the validity of this new control method.
Key words: shoot through; zero voltage switching; zero current switching; thermal balance
Research on transmitter and receiver of wireless power transmission based on magnetic resonance coupling
HUANG Hui, HUANG Xue-liang, TAN Lin-lin
(School of Electrical Engineering, Southeast University, Nanjing 210096, China)
Abstract: Self-resonance coupling is a new technology for wireless power transmission, which can transfer energy in middle distance. Transmitters and receivers are core parts to achieve wireless power transmission. An antenna has a part that amplifies a flux to make the antenna have a larger effective size than its actual size. This paper analyses the conversion efficiency between transmitting and receiving antenna from the point of magnetic field, getting the relation between the parameters of antennae and efficiency. It is helpful to choose the parameters of antennae with the purpose of achieving optimal result. At last, a wireless power transmission prototype based on magnetic resonance coupling was designed in this paper, and then verifying the theoretical analysis in experiments. Theoretical and experimental results show that the coil turns and the size of the coil radius of the antennae have an important influence on the efficiency. 10 Refs. In Chinese.
Key words: wireless power transmission; resonance; antenna; efficiency
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 32—35.
Research on arc-suppression and fault line selection of single-phase-to-ground fault in resonant grounded systems
ZHANG Ming, LIU Jian-zheng, MEI Hong-ming, LIU Shu
(Depart of Electrical Engineering and Applied Electronic Technology, Tsinghua University, Beijing, China)
Abstract: The traditional algorithm based on active component of zero-sequence current fails to select the fault line frequently. The paper analyzes the causes to the fail of the fault line selection through theoretical analysis, and combines the control of arc-suppression and the fault line selection of single-phase-to-ground fault in resonant grounded systems by optimizing the switching of the damping resistor. The simulation results show that the improved algorithm is more accurate on fault line selection. The hardware and software design of the device of arc-suppression and fault line selection is introduced. 8 Refs. In Chinese.
Key words: resonant grounded system; single-phase-to-ground fault; arc-suppression; fault line selection; active component algorithm
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 36—39.
A matrix based fault location algorithm for distribution network with DG
WANG Yu-mei, GUO Hao, JI Li-miao
(Henan Polytechnic University, Jiaozuo 454000, China)
Abstract: The conventional automatic fault section locating, which has traditionally been designed assuming the system to be radial, is no longer suitable for the system with distributed generation (DG).A matrix algorithm for fault location in complex multi-source distribution networks is put forward in this paper, which can locate both the multiple fault and the end fault. The algorithm is also suitable for the cases with incomplete information and information distortion. In addition, distribution networks with a special form of isolation switch is disposed. Test results show that the approaches proposed are both correct and feasible. Hence they have great potential for application in real-time fault location for distribution networks.
Key words: fault location; matrix algorithm; incomplete information; information aberrance; DG
Influence of saturation-induced saliencies and asymmetry of stator winding to rotor position estimation based on high-frequency signal injection
ZHONG Li-ping, GU Qi-min, XU Hui-gang, KONG Wei-tao, XIA Bing
(Electric and Automation Engineering School, Changshu Institute of Technology, Changshu 215500, China)
Abstract: Besides the physical saliencies, there are additional saturation-induced saliencies in permanent magnet motor, which mainly affect the stator leakage inductance. In addition, the rotating magnetic field would become ellipse in shape due to the asymmetry of stator windings. The interaction of these two factors would enhance the negative-sequence current harmonics and bring some error to rotor position estimation. This paper discussed this issue from both hand of theory and experiment, and primitively demonstrated the reason the negative-sequence current harmonics occurred and its effects, and the measures to solve it are also presented. 10 Refs. In Chinese.
Key words: saturation-induced saliencies; negative-sequence-component; asymmetry
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 44—47.
Winding loss modeling and application for push-pull transformer
MAO Xing-kui, HUANG Cong-yuan, CHEN Wei
(College of Electrical Engineering and Automation, Fuzhou University, Fuzhou 350108, China)
Abstract: Because of the four windings operating at time-sharing mode, AC winding model of push-pull transformer is different from the model of high-frequency power transformer with windings operating simultaneously. By the deep research on the MMF balance characteristics of the windings harmonic excitation currents, the new winding loss model was built for push-pull transformer. Based on the analysis, the total winding loss can be considered as the sum of the winding loss of two non-tapped forward-type transformers with respect to the related harmonic excitations. Based on this model, AC winding resistance measuring schemes for each harmonic were developed. The new model was verified by a 400W planar transformer optimal design and can be used to design the high-performance push-pull transformer conveniently. 6 Refs. In Chinese.
Key words: eddy current loss; winding techniques; planar transformer
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 48—51.
Study of CVCF inverter based on AC PR control
QI Ying-chuan1, HU Rong-qiang1, MENG Xiang-lin2, QI Cheng-chao2
(1. Automatic Academy, Wuhan University of Technology, Wuhan 430070, China;
2. Department of Mechanical-Electric, Air Force Radar Academy, Wuhan 430019, China)
Abstract：A new control method of constant voltage and constant frequency (CVCF) sine waveform inverters was given by alternative current proportional and resonant (PR) regulator, and the alternative current PR regulator of the inverter voltage main-control loop was designed. the control principle of phase error free and amplitude approximate error free to AC reference signal were analyzed. The relationship between the harmonic sources with the system parameters was discussed, and the parameters design of the PR regulator was given through root locus method. For output waveform harmonic distortion problems of the inverter non-linear load, the regulator type and design parameters of the harmonic compensation circuit were given and stability was discussed. The experiment circuit was designed, and the PR regulator was realized by the TMS320LF2407A. The validity of the designing and analyzing method were proved by the experiment. 7 Refs. In Chinese.
Key words: sine waveform inverter; waveform-control; AC proportional and resonant regulator; harmonic compensation; non-linear load
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 52—55.
Investigations on architecture and operation pattern of future power grid
XIAO Liye, LIN Liang-zhen
(Key Laboratory of Applied Superconductivity, Chinese Academy of Sciences, Beijing 100190, China; Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China)
Abstract: The new energy revolution, of which the primary energy will be based on renewable energy and the terminal energy will be based on electric power, will need to develop a corresponding future power grid. Based on the characteristics of future energy resources, the stability requirements of the power grid, and the future demand of power consumers for the DC power supply, a DC-based power grid which includes transmission system, distribution system and distributed network should be developed. In order to solve energy supply problems caused by the intermittent and non-stability from the renewable energy, one should make full use of the complementarities of future energy resources distributed in the wide area through the MP-MC transmission mode (Multiple Powers to Multiple Consumers), building a "wide-area super virtual power plants" (WASVPP) which covers all the major power plants in a wide range, and allowing the consumers get stable and reliable supply of electricity from the "Cloud Powering" generated by WASVPP.
Key words: renewable energy; DC power grid; distributed power grid; charging station for electric vehicles; superconducting power transmission cable; complementarities of the energy resources; virtual power plant; cloud powering
Experimental research of loosely coupled transformer in contactless power transfer system
ZHENG Ying-nan, CHEN Hong, ZHANG Xi-en
(Key Lab of Power Electronics for Energy Conservation and Motor Drive of Hebei Province,
Dept. of Electrical Engineering, Yanshan University, Qinhuangdao 066004, China)
Abstract: As one of the key part in the contactless power transfer system, the loosely coupled transformer has a larger air gap which makes the transformer have higher leakage inductances and lower coupling coefficient, so the efficiency and transfer character is very low. In the paper, we analyse the factors which have relation with the coupling coefficient in the transformer, and make simulation about the U、E-type magnetic core respectively when the air gap and winding location are changing with the help of ANSYS software, and we can find that the air gap and winding location have what affection to the coupling coefficient from the distribution and direction of the magnetic line. Furthermore, we find a new loosely coupled transformer which is made of some improved magnetic structure to improve the coupling coefficient, and the experiments testify the correctness of analysis and conclusion of the paper.
Key words: loosely coupled transformer; contactless power transfer; ANSYS
Research of magnetic latching automotive power switches based on CAN bus
LIU Xiang-jun, WANG Zhi-qiang, ZHANG Zhi-feng, ZHANG Pei-ming
(Fuzhou University, Fuzhou 350108, China)
Abstract: In view of the key issues present currently in the automotive power switch, such as the high power loss of electromagnetic coil, the contact corrosion caused by the arc, and the single-purpose function etc., a new idea about the magnetic latching hybrid automobile power switch is proposed in this paper. A control method of the hybrid magnetic latching automotive power switch is presented and the hybrid control scheme is optimized according to the dynamic characteristics of magnetic latching relay and corresponding mathematic algorithm. On the basis of above, the CAN bus technology is introduced to the control system of switch, and the real-time control and the protection function are realized. The experiments of the prototype verify that the new type automotive power switch has the functions of good automatic control, overload protection and switching without arc. Consequently, the performance of the control and protection of the power switch is improved remarkably and the reliability is enhanced.
Key words: magnetic latching; automotive power switch; hybrid; CAN bus
Influence of MOA to very fast transient over-voltage
YANG Xiao-liang1,2, XU Jian-yuan1,2, LIN Xin1,2, LI Xiao-lei3
(1. Shenyang University of Technology; 2.The Key Laboratory of Liaoning Province for Grid Disaster Prediction and Monitoring of Power Equipment Failures, Shenyang 110870, China; 3. Substation of Huaian Power Supply Company, Huaian 223002, China)
Abstract: The simulation of the very fast transient over-voltages (VFTO) caused during disconnecting switches (DS) operation is done by the EMTP software．The suppression of VFTO by MOA is studied．The very fast transient voltages caused by four operation modes of disconnecting switches of GIS in 550kV substation is calculated and analyzed．The position of MOA placed in the GIS bus is optimized．The results show that under normal operating conditions，the smallest value for MOA to suppress VFTO caused during disconnecting switches operation is 10m-20m away from the head of bus, and that is the best position. In addition, MOA should be installed closely to the transformer, and it is generally considered that the distance is less than 10 m. This conclusion is used as the reference to design the position of MOA in GIS, and it also has a very important practical significance in the actual project.
Key words: GIS; disconnecting switches; VFTO; MOA
Study of ultraviolet online monitoring system for the contaminant level of insulators
XIONG Lan1，LIU Yu1，HE You-zhong1，XIAO Bo2，WANG Li2，HE Wei1
(1. State Key Laboratory of Power Transmission Equipments & System Security and New Technology, Chongqing University, Chongqing 400030, China; 2. City Power Supply of Chongqing Electric Power Company, Chongqing 400015, China)
Abstract: In some districts with severe air pollution, the flashover of insulators takes place frequently and threats the safety operation of power system. In order to realize real-time monitoring for the contamination state of insulators, this paper designed an ultraviolet monitoring system based on ultraviolet pulse method. Simulation tests were executed with this system on composite insulator FXBW-110/70 and porcelain insulator XP-160 under different operating voltages and contamination levels with the presence of faulty insulators, then the number of ultraviolet pulses was counted and sent back to information center. The experimental results proved that the intensity of ultraviolet pulses can characterize the discharge level of contamination insulator, and the variation trend of ultraviolet pulses can distinguish if the discharge source is a polluted or a faulty insulator. This online monitoring system is a kind of non-contact detector with enough wide monitoring distance and low interference, which makes it possible to be applied in overhead transmission line and power station. 8 Refs. In Chinese.
Key words: insulator; contamination; surface discharges; ultraviolet; online monitoring
// Adv. Tech. of Elec. Eng. & Energy, 2011, 30(1). 79—83.
Experiment of crack detection of metal plate based on electromagnetically induced acoustic emission
ZHANG Chuang1, LIU Su-zhen1, YANG Qing-xin1, 2, JIN Liang1, LI Na3
(1. Province-Ministry Joint Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability,
Hebei University of Technology, Tianjin 300130, China; 2. Tianjin Polytechnic University, Tianjin 300160, China;
3. CNPC Bohai Equipment Chengde Petroleum Machinery CO., LTD, Chengde 067000, China)
Abstract: Nondestructive detection can be realized with the effect that the dynamic electromagnetic loading on the sheet metal can generate a stress field stimulating stress waves from the defects. The principle and implementation procedure of the electromagnetically induced acoustic emission (EMAE) is thoroughly analyzed in this paper. The high-current pulse generator which is used in the EMAE experiment is designed. The simple time-frequency analysis to the experimental signal is achieved by using fast Fourier transform (FFT). It researches the change patterns of EMAE signal with the different specimens and electromagnetic loading conditions. It verifies that it could excite the phenomenon of EMAE in the metal plate with the crack. The experimental results lay a good foundation for the engineering application of EMAE.
Key words: electromagnetically induced acoustic emission; high current load; nondestructive testing; spectrum analysis
|
