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Comparison of two basic structures in magnetically-coupled resonant wireless power transfer

Diangong Jishu Xuebao/Transactions of China Electrotechnical Society 2013年第SUPPL.2期28卷 18-22页

作者： Zhang, Yiming Zhao, Zhengming Yuan, Liqiang Lu, Ting State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Tsinghua University Beijing 100084 China

Wireless power transfer (WPT) has been a research focus in recent decades. Based on magnetically-coupled resonant WPT (MCR-WPT), this paper made a comparison of two basic structures in MCR-WPT: the two-coil structure and the four-coil structure. Their equivalent circuits were built. To illuminate the difference between these two structures, the input impedance, the transfer efficiency, and the load matching were studied and tested by experimental results. The conclusion is drawn that without reducing the transfer efficiency, the addition of the source coil and the load coil in the four-coil structure makes it easier to match the source and the load than the two-coil structure.

关键词： Magnetic resonance

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Research on generation and execution of coordination strategy for bi-directional and interactive coordinated voltage control between provincial and district levels

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Dianwang Jishu/power System Technology 2013年第12期37卷 3426-3432页

作者： Wang, Bin Guo, Qinglai Sun, Hongbin Li, Haifeng Luo, Jianyu Zhang, Boming Wu, Wenchuan State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Jiangsu Electrical Power Dispatching and Control Center Nanjing 210024 Jiangsu Province China

To achieve the goal of bi-directional and interactive coordinated voltage control between provincial and district levels, the study is focused generation and execution of coordination strategy for bi-directional and interactive coordinated voltage control between provincial and district levels. Firstly, the method to generate the bi-directional and interactive coordination strategy between provincial and district levels is proposed, and the gateway coordination state transition diagram is designed to intuitionally express the criterion of the interaction between the AVC systems belonging to the upper and lower level systems respectively;then, the regularization method for expanded coordinated secondary voltage control suitable to provincial power network and the regularization method suitable to district power network are put forward respectively to realize mutual support between power networks in provincial level and district level. Results from simulation examples and on-site operations show that the proposed method is feasible and effective as well.

关键词： Electric power transmission networks

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Comparison of Two Basic Structures in Magnetically-Coupled Resonant Wireless power Transfer

Comparison of Two Basic Structures in Magnetically-Coupled R...

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第十五届中国科协年会

作者： ZHANG Yiming ZHAO Zhengming CHEN Kainan State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical EngineeringTsinghua UniversityBeijing 100084China

Wireless power transfer (WPT) has been a research focus in recent *** on magnetically-coupled resonant wireless power transfer (MCR-WPT),this paper made a comparison of 2 basic structures in MCR-WPT,namely the 2-coil structure and the 4-coil *** equivalent electric circuits were *** illuminate the difference between these 2 structures,the input impedance,the transfer efficiency,and the load matching were studied and verified by experimental *** conclusion can be drawn that without reducing the transfer efficiency,the additions of the source coil and the load coil in the 4-coil structure make it easier for the system to perfectly match the source and the load.

关键词： wireless power transfer magnetic resonance comparison structure

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A non-iterative affine arithmetic methodology for interval power flow analysis of transmission network

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2013年第19期33卷 76-83页

作者： Ding, Tao Bo, Rui Guo, Qinglai Sun, Hongbin Wu, Wenchuan Zhang, Boming State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Midwest ISO St. Paul 55108 United States

power flow exhibits uncertainty when power injections randomly fluctuate. The variables of power flow problem are correlated through the constraints set forth by power flow equations. Affine arithmetic can effectively overcome the correlation and therefore is adopted in this paper. In order to improve the computational efficiency, non-iterative method was proposed, which can transform the interval power flow problem into optimization problems. Linear programming, nonlinear programming and quadratic programming optimization models were established to obtain intervals of nodal voltage magnitude, phase angle, branch active power and reactive power, respectively. simulation results of 9-bus and 57-bus test system show that the power flow interval obtained by the proposed algorithm is nearly the same as that by iterative algorithms, whereas the branch power flow results are better. The interval power flow problem can be solved quickly and efficiently with time complexity approximately O(m3). As well, parallel computing can be implemented to achieve promising improvement in computation time. © 2013 Chinese Society for Electrical Engineering.

关键词： Quadratic programming

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A fast transient simulation model of DFIG based on the piecewise averaging method

A fast transient simulation model of DFIG based on the piece...

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2nd IET Renewable power generation Conference (RPG 2013)

作者： G. Feng Y. Xu Y. Chen H. Gao L. Chen Tsinghua University Beijing Beijing CN State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China

ISBN: (纸本)9781629936017

Due to the power electronic devices in doubly fed induction generators (DFIG), it is very time consuming to simulate the electromagnetic transients of DFIG using its detailed model. Thus it is necessary to have appropriately simplified model of DFIG that maintains desirable accuracy. In this paper, the piecewise averaged model of PWM converters is introduced and applied to the modelling of DFIG. The proposed model divides the simulation time interval into switching periods and recalculates the averaged state equations of PWM converters in each switching cycle. In addition, a predictorcorrector based EMTP algorithm is designed to iteratively solve the model. Instead of treating switching events at the time points when they happen, the new algorithm solves all the switching instants in a switching cycle at the same time, which avoids frequency modification of the system conductance matrix and speeds up EMT simulations of DFIG. simulation results of a single-machine infinity bus system with a DFIG show that the proposed model and algorithm can achieve satisfactory accuracy and efficiency.

关键词： Average modelling Doubly fed induction generators Electromagnetic transient simulation

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Substation-dispatch center two-level distributed state estimation

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Dianli Xitong Zidonghua/Automation of Electric power systems 2012年第7期36卷 44-50+91页

作者： Li, Qingxin Sun, Hongbin Wang, Jing Zhang, Boming Wu, Wenchuan Guo, Qinglai State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China

A two-level distributed state estimation method for substation-dispatch center is proposed. After zero impedance three-phase state estimation based on KCL has been applied in substation, up load ripe data are treated in dispatch center level and the single-phase state estimation for all grid implemented. The detailed discussions about the architecture, algorithm, ripe data transmission, time setting and period selection, transmission protocol and transition scheme for the method are given. The results of calculation example show that this method is in favor of simultaneously identifying three-phase bad data and topology error, reducing communication burden, and increasing the reliability of the dispatch center state estimation for all grid. © 2012 State Grid Electric power Research Institute Press.

关键词： State estimation

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Equivalent capacity of the lower voltage ride through for wind farm from overcurrent protection in power collection lines

Equivalent capacity of the lower voltage ride through for wi...

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11th IET International Conference on Developments in power systems Protection, DPSP 2012

作者： Wang, Bin Dong, Xinzhou Bo, Zhiqian State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China Alstom Grid Stafford ST17 4LX United Kingdom

ISBN: (纸本)9781849196208

Magnitude and duration of voltage sags are the most important two factors to the Lower Voltage Ride Through (LVRT) capacity of the wind generator. Since most voltage sags are caused by the system faults, and sag durations are controlled by the tripping time of overcurrent relay in power collection lines based on the sags' magnitude. The specification of the LVRT capacity of wind generator is introduced into the operation characteristics of the relay in power collection lines. The evaluation model of equivalent LVRT capacity to overcurrent protection is proposed in paper, and the equivalent LVRT capacities from zone I and zone II relay are quantified. Improvement measures are also proposed.

关键词： Overcurrent protection

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Substation switching electromagnetic transient analysis using the time domain integral equation with a high order implicit scheme

Substation switching electromagnetic transient analysis usin...

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2012 IEEE International Symposium on Electromagnetic Compatibility, EMC 2012

作者： Xiang, Hongjun Chang, Sughun Zou, Jun Heng Yuan, Jians Shenderey, Sergey V. State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Beijing 100084 China Electrical Environment Group Korea Electrotechnology Research Institute Changwon 641600 Korea Republic of

ISBN: (纸本)9781467320610

A fast electric field integral in time domain using the uneven discretization and the implicit scheme is proposed to calculate the switching electromagnetic transient at a substation. The switching transient currents and the resultant radiated electromagnetic field are calculated. The propose d approach has the strength to model the bus system at a substation with a more complicated and realistic configuration that is difficult to simulate using the circuit-based method, because all the electromagnetic couplings within the bus system are included globally. The proposed method might be one of good candidates to predicate the EMI level at a substation. © 2012 IEEE.

关键词： Electric fields

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Application and benefit analysis of substation state estimation

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Dianli Xitong Baohu yu Kongzhi/power System Protection and control 2012年第12期40卷 56-61页

作者： Li, Qing-Xin Wang, De-Xing Sun, Hong-Bin Wu, Wen-Chuan Wang, Jing Guo, Qing-Lai Zhang, Bo-Ming State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Beijing 100084 China East China Electric Power Dispatch and Control Sub-Center East China Grid Company Limited Shanghai 200002 China

A substation three-phase nonlinear state estimation method based on zero impedance branches helps to identify topology and analogy errors at substation level and accordingly enhances the control center's state estimation reliability and accuracy. Some issues during the practical implementation process of the technology are reported, such as the hardware configuration, measurement integration, the communication between substation and control center, time setting and period selection. The benefits of the proposed technology have also been analyzed. It is shown that this technology has high reliability and low burden on communication, and improves the ability of monitoring of power grids and the reliability of the real-time power network model significantly. The proposed technology is verified effective by both simulation experiments and field-site applications in East China power Grid, and is well qualified for real-time online applications, which has broad popularization and application prospects.

关键词： State estimation

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EQUIVALENT CAPACITY OF THE LOWER VOLTAGE RIDE THROUGH FOR WIND FARM FROM OVERCURRENT PROTECTION IN power COLLECTION LINES

EQUIVALENT CAPACITY OF THE LOWER VOLTAGE RIDE THROUGH FOR WI...

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IET International Conference on Developments in power System Protection

作者： Bin Wang Xinzhou Dong Zhiqian Bo State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Alstom Grid

ISBN: (纸本)9781622761050

关键词： Wind Farm Lower Voltage Ride Through Overcurrent Protection power collection lines

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