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Eigenvalue analysis of multi-mode sub-synchronous resonance for multimachine plant-to-grid transmission systems with fixed series compensation

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2008年第SUPPL.期28卷 13-18页

作者： Zhang, Shu-Qing Xie, Xiao-Rong Yang, Ting-Zhi Liu, Shi-Yu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Dept. of Electrical Engineering Tsinghua University Haidian District Beijing 100084 China

For some domestic large thermal power plants delivering electric energy over long distances, the sub-synchronous resonance (SSR), which is induced by the fixed series compensation (FSC), attracts much attention. Eigenvalue analysis is one of the primary methods to assess the risk and explore the countermeasure. However, for handling multi-machine and multi-mode SSR problems, no practical toolkit based on eigenvalue analysis is on hand for the moment. In this paper, a systematic modeling approach and analysis flows for the purpose of eigenvalue analysis of multimachine plant-to-grid transmission systems with FSC were proposed. The equating technique of machines and networks was presented, and the effect of the q-axis damping windings on the SSR was also explored. The applicability of the proposed method was verified with an actual multimachine system. Furthermore, its advantage over existing SMIB based eigenvalue analysis was clarified by a comparative study between the original multi-machine system and the simplified single-machine system.

关键词： Eigenvalues and eigenfunctions

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Benefit Assessment Analysis of Electrochemical Energy Storage

Benefit Assessment Analysis of Electrochemical Energy Storag...

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power Science and Technology (ICPST), IEEE International Conference on

作者： Junliang Ma Zhidong Wang Shuming Zhang School of Electrical Engineering Northeast Electric Power University Jilin China Transmission Grid Planning Center State Grid Economic and Technological Research Institute Co. Ltd Beijing China State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China

Along with the power fluctuation and other problems caused by large-scale grid connection of renewable energy, electrochemical energy storage has been widely concerned by researchers. Firstly, the technical characteristics and application scenarios of important electrochemical energy storage are summarized in this paper. Then the analysis focus on the evaluation indexes of the economic and social benefits of electrochemical energy storage on the generation side, grid side and user side. Finally, in order to adapt to the landing of carbon peaking and carbon neutral targets, and combined with the implementation of time-sharing tariffs, energy storage planning problems that need further in-depth research are proposed in view of the shortcomings in existing energy storage planning studies, which are of great significance for improving the adaptability of subsequent energy storage planning studies.

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Improved simultaneous extrapolation in sharp impulse signals in time and frequency domains

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2006年第18期26卷 133-137页

作者： Zou, Jun Guo, Jian He, Jin-Liang Zhang, Bo Teng, Wen-Rui State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China Dept. of Electrical Engineering Henan University of Technology Zhengzhou 450042 China

The characteristic of the transient response of the grounding system takes on a fast rising and slow damping with the lightning excitation. An improved simultaneous time and frequency domain extrapolation method is presented based on Hermite function expansion, which takes the above mentioned characteristic of the transient signal into account, using early time response and low-frequency data, the complete electromagnetic response is generated. By using mutually complementary data, simultaneous extrapolation in time and frequency domains are carried out by using the Hermite polynomials as the basis function. However, the extrapolation method is not suitable to deal with the transient response with the fast pulse excitation. The improvement for the extrapolation method is to pre- and post-process the transient response data with the fast pulse excitation. As a pre-processed procedure, in order to reduce the condition number of the matrix used for determined the coefficient of basis function, the scale transformation is used in time and frequency domain respectively, and the data in time domain is smoothed and padded with zero. An adaptive algorithm to determine the order of Hermite function is also proposed. As a post-processed step, the transient data are smoothed by using GPOF to obtain a convergent result. The numerical example and the field measurement are presented to illustrate the application of this methodology. The method proposed enhances the ability of the simultaneous time and frequency extrapolation techniques.

关键词： Signal processing

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Adaptive Galerkin approach of the indirect boundary element method for calculating 3D linear magnetostatic field

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2006年第1期26卷 96-100页

作者： Zou, Jun He, Jin-Liang Yu, Hai-Yu Teng, Wen-Rui State Key Lab. of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing 100084 China Dept. of Electrical Engineering Henan University of Technology Zhengzhou 450042 China

The indirect boundary element method has some special advantages for the 3D linear magnetostatic field calculation by using the equivalent magnetic surface charge. In order to improve the accuracy of solutions and decrease the computational costs, an adaptive Galerkin approach to solve the magnetostatic integral equation is presented by using the h-type refinement technology. The basic idea of the proposed approach can be summarized as follows. The error of magnetic flux density is globally minimized in the Galerkin sense in the implementation, so the continuity error of magnetic flux density of each element can be served as a criterion to guide the adaptive refinement. The singularity of geometric corners and edges can be overcome due to the scheme of the discretization of the integral equation with Galerkin's approach. In addition, a local resolution technology is proposed, which leads to the minimal refined unknown. The numerical examples show the proposed method is efficient and accurate by comparison to the analytical solutions and the measured results.

关键词： Magnetic fields

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Lightning protection study of transmission line, Part II: Analysis methods

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Gaodianya Jishu/High Voltage Engineering 2009年第12期35卷 2910-2916页

作者： Zeng, Rong He, Jin-Liang Chen, Shui-Ming State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

Design is the key of lightning protection of transmission lines, and lightning protection analysis is the base to estimate the lightning protection behaviors of transmission line and the effect of lightning protection measures for transmission line. We mainly discussed the development states and the existed problems in lightning protection analysis of transmission line in the world, presented the analysis methods on the lightning backflash and shielding failure of transmission line and their comprehensive applications, and proposed the suitable models and methods for lightning protection analysis of transmission line. The whole-wave- progress analysis model should be applied to calculate the lightning transient characteristics of transmission line when the lightning strikes the tower or the overhead ground wires of transmission line;different analysis methods, such as electrogeometric method, the leader propagating model and the fractal model, should be used to calculate the shielding failure behaviors of transmission line. The lightning protection analysis of transmission lines should consider the micro-typological characteristics and the area difference of lightning parameters along transmission line, and comprehensively estimate the lightning protection behaviors of transmission line sections.

关键词： Electric lines

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Voltage balance optimisation among subsystems of wind-photovoltaic-ES hybrid generating system

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The Journal of Engineering 2017年第13期2017卷 854-858页

作者： Han Wu Yan Li Zongxiang Lu Haiyan Tang State Key Lab of Control and Simulation of Power Systems and Generation Equipments (Dept. of Electrical Engineering Tsinghua University) Haidian District Beijing 100084 People's Republic of China North China Electric Power Research Institute Co. Ltd Beijing 100045 People's Republic of China State Key Laboratory of Operation and Control of Renewable Energy & Storage Systems (China Electric Power Research Institute) Haidian District Beijing 100192 People's Republic of China

Wind-photovoltaic-energy storage (ES) hybrid generating system has numerous reactive power sources. It is crucially important for coordinated control of these reactive power sources. According to the test results, there are unbalanced control problem in subsystem voltage of the hybrid generating system. The problem caused reactive power circulation and loop current. A subsystem voltage balance optimisation strategy is proposed to solve the problem. The case study shows the efficiency of the proposed strategies.

关键词： electric potential wind power photovoltaic power systems reactive power electric power generation reactive power sources wind-photovoltaic-ES hybrid generating system subsystems voltage balance optimisation

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Gas generation Characteristics of Transformer oil under Combined AC-DC Voltages in the Process of Arcing

Gas Generation Characteristics of Transformer oil under Comb...

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Annual Report Conference on Electrical Insulation and Dielectric Phenomena

作者： Y.X. Zhou Y.C. Sha X.X. Jiang Q.H. Sun Y.S. Wang J.H. Tian State Key Lab of Control and Simulation of Power Systems and Generation Equipments Department of Electrical Engineering Tsinghua University Haidian District Beijing China

ISBN: (纸本)9781457709852

As an important equipment, convertor transformer plays a crucial role in ultra high voltage direct current (UHVDC). How to improve the safety running level of convertor transformers is a key problem to be solved imminently. Compared with AC power transformers, the valve side windings of convertor transformers will endure combined AC-DC voltage. In these conditions, the gas generation characteristics in oil for convertor transformers will be more complicated. In this paper, according to the operational principle of convertor transformers, the ratios between AC and DC voltage on valve side windings in the star connection and triangular connection were 77.1% and 83.7% respectively. Based on the above results, 65 kV peak voltages in 5 different AC and DC voltage forms were applied to the needle-plate electrode model for 2 hours. The discharge current and voltage waveforms were recorded and the arc current pulses had a short lasting time about 1.2 ms. Then the mean discharge energy was calculated at 0.1 to 0.3 J. At the same time, the gas generation characteristics under combined AC-DC voltage were obtained by using the gas chromatographic analysis method. The variations of amounts and generation rates of characteristic gases were measured with time during 2 hours, which provided fault judgment criterions and experimental experience. The experimental results showed that the amounts and generation rates of H2, C2H2 and total hydrocarbon under the pure DC voltage or combined AC-DC voltage were more than those under the pure AC voltage. It might illustrate the fact that effects of different voltage forms would lead to different gas generation characteristics could not be ignored.

关键词： Combined AC-DC voltage Needle-plate electrode model Gas generation Characteristics

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Lightning protection study of transmission line, Part III: Protection measures

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Gaodianya Jishu/High Voltage Engineering 2009年第12期35卷 2917-2923页

作者： He, Jin-Liang Zeng, Rong Chen, Shui-Ming State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

The lightning accidents threaten the safe operation of power system. We comprehensively analyzed the developing states, the existed problems in analysis methods and measures of transmission line lightning protection, and discussed the key issues of transmission line lightning protection in China that should be studied. The lightning protection measures are divided into back-up type and leading-type methods, so-called back-up type method is used in lightning protection of transmission line in China, which complicates lightning protection;but the so-called leading-type method is used in other countries, which simplifies lightning protection. The lightning protection measures for different sections of transmission lines should be comprehensively estimated and proposed by considering the micro-topographical feature and the regional performances of lightning parameters along transmission line. The lightning protection should be fully considered in transmission line design, reducing shielding angle of overhead wire, decreasing grounding resistances of tower footings, and suitably installing line surge arresters are fundamental methods of lightning protection of new transmission line.

关键词： Electric lines

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Lightning protection study of transmission line, Part I: Lightning parameters

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Gaodianya Jishu/High Voltage Engineering 2009年第12期35卷 2903-2909页

作者： Chen, Shui-Ming He, Jin-Liang Zeng, Rong State Key Lab. of Control and Simulation of Power Systems and Generation Equipment Department of Electrical Engineering Tsinghua University Beijing 100084 China

Obtaining actual lightning parameters is the fundament of lightning protection of transmission lines. Based on the comprehensive analysis on the methods to acquire lightning parameters, we analyzed the current research states and existed problems of lightning parameters, including annual lightning day, ground flash density, magnitude and waveform of lightning current. The lightning activities have obvious topographical feature, presently the lightning location system (LLS) should be fully applied to acquire the annual lightning day, ground flash density, magnitude of lightning current in different areas. Moreover, the monitoring devices of lightning current should be installed on typical transmission towers with different voltage grades in different areas to obtain the characteristics of real lightning current waveforms and magnitudes, and calibrate and check the lightning current magnitudes obtained from LLS. All these would make the lightning protection of power system focusing on the actual targets. Four sets of the developed monitoring devices of lightning current were installed, and the first lightning current waveform in China, which was similar to the standard waveform recommended by CIGRE, was recorded.

关键词： Electric lines

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Research of protection communication system in process level of intelligent substation

Research of protection communication system in process level...

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International Conference on Advanced power System Automation and Protection (APAP)

作者： Fei Xu Bin Wang Xinzhou Dong Runbin Cao Kun Liu Yuelin Yang Tingting Wu State Key Lab of Control and Simulation of Power Systems and Generation Equipments Tsinghua University Beijing China College of information and electrical engineering China Agricultural University college of information and electrical engineering China Agricultural University School of Electrical Engineering & Renewable Energy China Three Gorges University Yichang China

The paper mainly focuses on the communication problem based on IEC61850 communication protocol. As in the process level communication system: MU (Merging Unit)-Switch-DIPC (Digital Integrated Protection and control system), the stability of SMV packets transmission is very important. The transmission delay of the process level communication is the key problem that may restrict the protection algorithm and capability. In the meantime, GPS synchronization problem of MUs, protection capability of the integrated protection device and stability of SMV message transmission based on the existing DIPC(DIP-01) system will also be discussed in the paper. Through the experiment and analysis, the paper gives out the key factors that lead to the message transmission delay and packets loss. The work at last gives out some primary ideas to improve the protection capability.

关键词： Random access memory Switches Synchronization Optical fiber devices Delay

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