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2007 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, vol.1

作者： Zhiguo Tang Chengrong Li Wei Wang Hui Wang Li Wang Yansheng Ding Beijing Key Laboratory of High Voltage & EMC North China Electric Power University China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University China State Grid Corporation of China Beijing China

The radiation and propagation of electromagnetic (EM) waves generated from PD caused by the obstruction of main transformer components are studied by FDTD simulation in order to get more information for PD location and diagnosis. Current filament, perfect conductive cylinder and perfect conductive spiral coil models are used to simulate the radiation and the influences of iron-core and transformer coil to the propagation of EM waves. The results demonstrate dynamic propagation process of EM waves in time order, and prove the correctness of the shortest optical path principle. But the attenuation and distortion of EM waves-especially the first peak amplitude-caused by the obstruction of large solid conductive obstacle like iron-core are quite intensive that it may cause great difficulties to identify exact arriving time position of incident waves coming along the shortest optical path. While the influences of the coil to the propagation of EM waves are so little that HF EM waves can penetrate it in almost linear path.

关键词： Electromagnetic propagation Electromagnetic scattering Character generation power generation Partial discharges power transformers Finite difference methods Time domain analysis Electromagnetic radiation Coils

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Numerical prediction of EMI on the secondary DC cable in cable tunnel due to a direct lightning strike in substation

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IEEE TRANSACTIONS ON MAGNETICS 2006年第4期42卷 863-866页

作者： Lei, Q Xiang, C Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education School of Electrical Engineering North China Electric Power University Hebei 071003 China

Electromagnetic interference (EMI) on secondary de cable in cable tunnel due to a direct lightning strike in substation threatens the safe operation of electronic equipment and system connected to the cable. In order to reduce EMI, the cable shield is generally connected to the grounding grid at both ends. Ground potential difference between two grounding points of the cable shield can be high due to high impedance of the grounding grid at high frequencies. In this paper, we present a hybrid method to analyze this complex system. As a result, both the current flowing in the cable shield and the transverse voltage between the cable core and shield are calculated. Compared with the measured results, the proposed method is demonstrated to be correct and effective.

关键词： electromagnetic interference (EMI) grounding grid in substation lightning secondary cable

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Fuzzy excitation control based on wide-area measurements

Fuzzy excitation control based on wide-area measurements

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7th IET International Conference on Advances in power system control, Operation and Management, APSCOM 2006

作者： Liu, Xingjie Mi, Zengqiang Zhao, Hongshan Key Laboratory of Power System Protection Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hebei China

ISBN: (纸本)0863412467

In this paper, a fuzzy excitation controller based on wide-are measurement system (WAMS) is built, in which the voltage deviation and its rate are introduced as the input of main-controller, while the deviation and corresponding rate of local generator's frequency and center-of-inertia frequency are acted as the input of the second controller to indicate the global information. The multi-machines system model is firstly set up with MATLAB/PST. Then the digital simulation is conducted to compare the influences of PID excitation controller and fuzzy excitation controller based on WAMS on the transient stability. Results show that applying the fuzzy excitation controller proposed in this paper, the ability to endure serious disturbances can be strengthened and transient stability can be improved.

关键词： controllers

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Voltage waveform deadbeat control of DVR

Voltage waveform deadbeat control of DVR

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7th IET International Conference on Advances in power system control, Operation and Management, APSCOM 2006

作者： Li, Peng Liu, Xuanxuan Bai, Qian Key Laboratory of Power System Protection Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hebei China

ISBN: (纸本)0863412467

Because the compensation signals of DVR are unpredictable, this paper advanced a deadbeat control algorithm for DVR voltage waveform tracking compensation. On the basis of state equations and state variables information of the system, a specific scheme is produced to realize voltage waveform tracking compensation, which includes a state observer a voltage forecast and a current forecast for a random load. The switch control signals of next sampling period are calculated so that the output voltage can track the reference voltage synchronously. The simulation results show that this control algorithm is correct and feasible.

关键词： Equations of state

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Computation of power line tower lightning surge impedance using the electromagnetic field method

Computation of power line tower lightning surge impedance us...

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17th International Zurich Symposium on Electromagnetic Compatibility, 2006

作者： Gao, Changzheng Li, N. Li, Bing Zhao, Zhibin Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Under Ministry of Education North China Electric Power University Baoding Hebei 071003 China

ISBN: (纸本)3952299049

The power line tower lightning surge impedance is computed using an electromagnetic field approach. After comparing the results computed by our method and those tested with both a vertical conductor and reduced scale 4-poles model of tower, the method we used is proved to be right and more practical as the soil and the grounding system of the tower can be considered in the method. Using this method, the lightning surge impedance of the full scale UHV tower with grounding system is analyzed and the results show that the lightning surge impedance of a tower on the perfect ground has a little difference with those of an actual tower considering both its grounding system and soil resistivity, and when the soil resistivity is changed, the surge impedance changes slightly. Furthermore, a circuit model of the tower is obtained by Vector Fitting method based on the results we computed. Using the circuit model, the lightning surge performance of a power transmission line can be analyzed more accurately by EMTP or other methods.

关键词： Lightning protection

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Subcell FDTD modeling of electrically thin dispersive layers using Z transforms

Subcell FDTD modeling of electrically thin dispersive layers...

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17th International Zurich Symposium on Electromagnetic Compatibility, 2006

作者： Jiao, Chaoqun Cui, Xiang Li, N. IEEE Key Laboratory of Power System Protection Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding 071003 Hehei Province China

ISBN: (纸本)3952299049

A novel technique for treating electrically thin dispersive layers with the finite-difference time-domain (FDTD) method based on Z transforms is introduced. The proposed model is based on the subcell technique, where the constitutive relations are locally averaged in the FDTD grid. The most significant feature of the proposed model is its ability to model rather complicated dispersive layers having multiple pole pairs. The model is validated with several numerical examples making comparison with the exact results.

关键词： Electromagnetic dispersion

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Analysis of power line tower lightning surge impedance using the time domain electromagnetic method

Analysis of power line tower lightning surge impedance using...

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4th Asia-Pacific Conference on Environmental Electromagnetics, CEEM'2006

作者： Mingxia, Zhang Xiang, Cui Lin, Li Changzheng, Gao Zhibin, Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding China

ISBN: (纸本)1424401836

A time domain electromagnetic field approach is proposed to investigate the lightning surge impedance of the full scale UHV tower with grounding system. The model, which is validated by comparing the result to those of other method, can be used to analyze the lightning surge performance of a power line more accurately. Finally, this method is applied to analyze the surge impedance and potential of a real UHV tower.

关键词： Electric lines

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The structure and realization of voltage sags monitoring system based on GPRS and web

The structure and realization of voltage sags monitoring sys...

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2006 China International Conference on Electricity Distribution, CICED 2006

作者： Chen, Pengliang Xiao, Xiangning Tao, Shun Ye, Zhifeng Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University 102206 China

ISBN: (纸本)0863416381

In this paper, the status of the study on the voltage sags monitoring at home and abroad is summarized. Based on the GPRS wireless communication and Web technology, the dynamic monitoring and data analysis system has designed for monitoring the voltage sags uninterrupted in a local network. The voltage sags in the receiving end network region are recorded, analyzed and counted by this system, at the same time, the information of these sags is transmitted to a remote computer using GPRS. This system can provide the policy-making support for alleviating the voltage quality questions. Based on Web, clients can login the service to scan periodical and non-periodical statistics reports of sag events.

关键词： monitoring

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Study on the SVPWM algorithm of N-level inverter in the context of non-orthogonal coordinates

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Frontiers of Electrical and Electronic Engineering in China 2006年第2期1卷 199-204页

作者： XIAO Xiang-ning JIANG Xu LIU Hao LIU Hui-wei KONG Sheng-li Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power UniversityBeijing 102206China Electric Power of Henan Zhengzhou 450000China

In this paper,the authors propose a new space vector pulse width modulation(SVPWM)algorithm based on non-orthogonal coordinates for N-level ***,it is pointed out that classicalαβcoordinates-based SVPWM has many shortcomings because of improper coordinate ***,a non-orthogonal coordinates-based SVPWM is proposed to solve these *** proposed algorithm can easily identify which sector the reference space vector falls in and conduct simple operations to find the duty cycle of each ***,it is verified that the proposed SVPWM is actually a pulse−width modulation(PWM)technology based on line voltages.

关键词： power electronics N-Level SVPWM KL coordinates

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Study of TCPS-PWM based high-voltage cascade multilevel H-bridge active power filter

Study of TCPS-PWM based high-voltage cascade multilevel H-br...

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2006 China International Conference on Electricity Distribution, CICED 2006

作者： Zhou, Guoliang Shi, Xinchun Guo, Xiuhong Fu, Chao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 China

ISBN: (纸本)0863416381

A novel control strategy for 11-level cascade H-bridge APF based on TCPS-PWM is proposed in this paper. When the cascade inverter is applied to active power filter for distribution system, it is expected that the switching frequency and the EMI will be dramatically reduced below that of the traditional one. By the strategy, each power unit operates with relatively low frequency. At the same time, the equivalent switching frequency is still high so as to meet the high tracing ability for better compensation performance. This paper also focuses on the transposing modulation method to solve the problem of the balance of each DC voltage. PSIM is adopted for simulation of 11-level cascade H-bridge high-voltage active power filter which is to compensate the 10kV distribution system. Analytical and simulated results show the feasibility and superiority of the proposed strategy.

关键词： Pulse width modulation

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