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IEEE General Meeting power& Energy Society

作者： T.S. Bi H.M. Xu S.F. Huang Q.X. Yang Key Laboratory f Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

Cascading trips caused by flow transferring are crucial for lots of well-known blackouts. For a power system with heavy load flow, once there is a fault, the system might suffer flow transferring after the fault clearing. However, for relays, they cannot know the sensing overcurrent is caused by internal faults or flow transferring. The relays will trip the overcurrent after the predefined time delay, which might result in flow transferring again and worsen the system state. Therefore, if relays pickup due to flow transferring, the back-up relay should be blocked until the thermal limit of the line reaches. In this paper, Flow Transferring Relativity Factor (FTRF) is suggested to estimate the flow distribution after a line is tripped. Moreover, based on the relationship of node injection and branch currents, the impact of transient period on the flow distribution is analyzed. Finally, a flow transferring identification algorithm is presented to distinguish flow transferring from internal fault caused by fault clearing. The simulation results of 10-generator 39-bus New England system show that the proposed flow transferring identification algorithm works well.

关键词： power system protection power system faults power system relaying power system dynamics power system transients Wide area measurements Fault diagnosis power system security Bismuth Delay effects

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The implementation of fuzzy adaptive PI controller in VSC-HVDC systems

The implementation of fuzzy adaptive PI controller in VSC-HV...

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IEEE PES power systems Conference and Exposition, PSCE

作者： Haifeng Liang Gengyin Li Ming Zhou Chengyong Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education Changping North China Electric Power University Beijing China

Focusing on the passive network, this paper analyzes the discrete mathematical model and its control strategy of the passive terminal of the VSC-HVDC system on the basis of the alpha-beta frame of axes. The method of the functioning-fuzzy-subset inference is introduced into automatic regulation of the proportional integral (PI) parameters. Based on the digital signal processor (DSP), the fuzzy PI control method is adopted and the VSC-HVDC experiment device is constructed. The experiment of constant AC voltage control based on fuzzy adaptive PI controller in transmitting power to passive network via VSC-HVDC system is developed. The experimental results show that the fuzzy controller with adaptive PI parameters for AC voltage control of VSC-HVDC system is effective.

关键词： Fuzzy control Fuzzy systems Programmable control Adaptive control control systems Voltage control Automatic control Passive networks Mathematical model Digital signal processors

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Substation Reactive power and Voltage control Using Fuzzy control Theory

Substation Reactive Power and Voltage Control Using Fuzzy Co...

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International Conference on Industrial and Information systems, IIS

作者： Zengqiang Mi Fei Wang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China

ISBN: (纸本)9781424439362

In this paper, with analyzing the existing questions of conventional nine-area voltage and reactive power integrated control method, a new fuzzy control logic based dynamic reactive power boundary substation voltage and reactive power integrated control method is proposed. The fuzzy logic control strategies of this method can finish the decoupling control of voltage and reactive power in tight coupled zone to improve the control performance, dynamic reactive power boundary related to the system voltage can preferably adapted to the load characteristics. The system structure, fuzzy logic control rules and membership function of the proposed method are introduced. Simulation results and practical operating data have proved that this approach shows better robustness and performance compared with the conventional nine-area control method, it can reduce the adjust times of transformer tap and capacitors effectively and increase the service life of the transformer tap changer and capacitors switch.

关键词： Substations Reactive power control Voltage control Fuzzy control control systems Centralized control Fuzzy logic Fuzzy sets Switches power system stability

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New Topological Structure of Combination Switch Based Reactive power Compensation Installation

New Topological Structure of Combination Switch Based Reacti...

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Pacific-Asia Conference on Circuits, Communications and systems, PACCS

作者： Fei Wang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China

A new topological structure of combination switch based reactive power compensation installation is presented in this paper. The new topological structure overcomes those shortcomings of traditional product satisfactorily by take advantage of the features of new system topological structure: concise structure, flexible configuration, high speed communication and powerful capacity of resisting disturbance. The new system topological structure and software program design features of this new installation are described in detail, contrastive analysis and practical test between the new installation and the traditional product are discussed. The results show that the new installation not only has the virtue of: structural standard, simply connection, intelligent identification, easy to extend, high reliability and high power density, but also improves the performance index by means of integrated intelligent control principle and compensation capacity dynamic modification.

关键词： Switches Reactive power ISO standards Reactive power control power system dynamics control systems Communication system control power system reliability Low voltage Access protocols

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Analysis on measuring performance of three Flicker Detecting Methods

Analysis on measuring performance of three Flicker Detecting...

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IEEE General Meeting power& Energy Society

作者： Qing Chen Xiufang Jia Chengyong Zhao Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China

Voltage fluctuation and flicker is an important aspect of power quality. The core of flicker analysis is to track the envelope of voltage signals and then calculate the short-term flicker severity P st , which is the premise of flicker source location. This paper firstly derives the formulas of extracting flicker envelope of signals containing harmonics using Teager energy operator and Hilbert transform. Then the measuring performance of Teager energy operator, Hilbert transform and square demodulation of flicker with one frequency, multi-frequencies and with harmonics are analyzed. After extracting the flicker envelope, the flicker frequency and amplitude error, and short-term flicker severity P st error are calculated. Besides the relationships between amplitude error and frequency, P st error and frequency with respect to these three methods are illustrated respectively. At last it is proved that Hilbert transform has the highest accuracy and stability than TEO and square demodulation with the increase of frequency.

关键词： Performance analysis Voltage fluctuations Demodulation power quality Signal analysis Position measurement Energy measurement Frequency measurement Harmonic analysis Stability

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Complete-independent control strategy of active and reactive power for VSC based HVDC system

Complete-independent control strategy of active and reactive...

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IEEE General Meeting power& Energy Society

作者： Chengyong Zhao Chunyi Guo Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Baoding Hebei China

The performance of VSC based HVDC system partially depends on its control strategy. Based on the steady state model of VSC-HVDC system, a power control strategy is proposed and a series of mathematical analysis expressions for power delivery are deduced using the coordinate conversion and variables substitution in terms of the original equations. The corresponding power controllers are designed using the PI controller and the nonlinear inverse system. Based on the strategy designed, the transmission limits of active power and reactive power are deduced. According to the circle characteristic of operation represented, it is proved theoretically that the control strategy can independently control the active and reactive power. Case studies are also carried out to testify the control strategy designed using the PSCAD/EMTDC software. Simulation results verify that the power control strategy designed can independently control active power and reactive power and the controllers have rapid responding speed, desirable stability, and highly steady state control accuracy.

关键词： control systems Reactive power control HVDC transmission Steady-state power control Nonlinear control systems Mathematical model power system modeling Mathematical analysis Nonlinear equations

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Feedback Linearization Based Nonlinear control Strategy of VSC-HVDC

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IFAC Proceedings Volumes 2009年第9期42卷 308-313页

作者： Gengyin Li Ming Yin Ming Zhou Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 P.R. China (Tel: +86 10 80798551) State Power Economic Research Institute Beijing 100761 P.R. China Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 P.R. China

The model of Voltage Source Converter (VSC) based HVDC in the synchronous dq reference frame is presented in this paper. The model includes the DC link model and the VSC models. The feedback linearization principle for Multi-input Multi-output plants is analyzed. Based on the analysis, nonlinear decoupling control strategies for the two VSCs are proposed. For one VSC, the proposed nonlinear control strategy enables it to decouple DC voltage and reactive power control, and for the other one, the strategy guarantees the control of active power and that of reactive power independently. Simulation was conducted with MATLAB/Simulink software to verify the proposed control strategies. The simulation results prove that the nonlinear decoupling control strategies are able to provide good performance.

关键词： Feedback linearization HVDC nonlinear control strategy voltage source converter (VSC)

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A fault location scheme based on spectrum characteristic of fault-generated high-frequency transient signals

A fault location scheme based on spectrum characteristic of ...

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IEEE General Meeting power& Energy Society

作者： S. F. Huang X. G. Wang Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing China

When a fault occurs on a transmission line, fault-generated high-frequency signals contains a lot of information about fault. This paper proposes a fault location scheme for transmission lines based on spectrum characteristic of high-frequency components, the difference of adjacent two natural frequencies in one ends of transmission line is used to compute fault distance. This method need not identify arriving time of first traveling wave and traveling wave from fault point, it is insensitive to swings, fault type, fault resistance and system source parameters. The scheme performance was proven using power system computer aided design (PSCAD) simulations in 500-kV power system considering critical fault cases.

关键词： Fault location power transmission lines PSCAD power system simulation power system transients Frequency Fault diagnosis Computational modeling Computer simulation power system faults

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Measurement of micro-scale two-phase flow in a pulsating heat pipe using electrical capacitance tomography

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Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering 2009年第17期29卷 103-107页

作者： Li, Jing-Tao Xiao, Hai-Ping Dong, Xiang-Yuan Liu, Shi Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Changping District Beijing 102206 China School of Energy and Environmental Engineering Zhongyuan Institute of Technology Zhengzhou 450007 Henan Province China

The electrical capacitance tomography (ECT) system was used to the visualization of the two-phase flow as well as the measurement of the film thickness in a pulsating heat pipe (PHP). The new-developed micro-sensor was also applied as a part of the flow channel, with the characteristics of heat transfer and hydrodynamics similar to the measured tube. The measurement accuracy and the image resolving power were improved as compared with the conventional sensors. So the applied area of the ECT technology was widened. The experimental results indicate that there might exist three flow patterns, i.e. bubble-liquid slug flow, semi-annular flow and annular flow, corresponding to different operating conditions. The measurement results of the film thickness compare well with the actual conditions, and the trend of the film thickness can realize the identification of the flow patterns.

关键词： Two phase flow

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Comparison of pitch angle control models of wind farm for power system analysis

Comparison of pitch angle control models of wind farm for po...

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IEEE General Meeting power& Energy Society

作者： Li. Lin Jing. Zhang Yihan. Yang Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China North China Grid Corporation Beijing China

With rapid development of wind power generation, the large capacity wind farms are built up and integrated into transmission network. The effect of wind farms on the grid becomes more serious and more extensive. In order to investigate the dynamic performances of the grid-connected wind farm and the interaction of the wind farms, it is necessary to present the appropriate models of wind farms, which can present the wind power characteristics completely and are not too complicated. In this paper, based on the detailed model of the pitch angle control system, two kinds of simplified pitch angle control models are deduced by mathematics equivalence method. Then the three models are adopted respectively, the relatively dynamic characteristics of the wind farm and the grid are compared. Later, the wind farm with different pitch angle control model is connected to the CIGRE B4-39 grid, and the simplified models are verified by simulation. Finally, the methods how to choice pitch angle control models are present.

关键词： power system modeling Wind farms power system analysis computing power system control power systems power system dynamics Mathematical model Wind power generation Wind energy control system synthesis

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