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2007 IEEE power Engineering Society General Meeting, PES

作者： Qin, Xiaohui Bi, Tianshu Yang, Qixun IEEE Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing 102206 China

ISBN: (纸本)1424412986

In this paper, a new method of hybrid non-linear state estimation with PMU is proposed. Firstly, the voltage phasor measurements are transformed into indirect equivalent branch current measurements, with which the conventional state estimator takes the impact of PMU into consideration. Secondly, the indirect measurement errors caused by the measurement transforming are analyzed and calculated in detail. Thirdly, the accuracy of hybrid estimator is analyzed in the paper. The simulation results show that the proposed method improves the accuracy of estimator and the convergence speed also. © 2007 IEEE.

关键词： State estimation

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Multi-layer disturbance processing system based on multiple information sources

Multi-layer disturbance processing system based on multiple ...

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2007 IEEE power Engineering Society General Meeting, PES

作者： Bi, Tianshu Li, Qian IEEE Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing 102206 China

ISBN: (纸本)1424412986

More and more IEDs have been commissioned in power systems, such as digital relays, PMUs, metering and control devices, fault recorders and so on. Once there is a disturbance (for example, fault, low-frequency oscillation, etc.), large amount of information will pour into the control center. Therefore, how to identify the disturbance and then take corresponding countermeasures is crucial for power system security and reliability. A multi-layer disturbance processing system based on multiple information sources is proposed in this paper. Firstly, the characteristics of different kinds of information sources, including PMUs, RTUs, digital relays and fault recorders, are analyzed. Secondly, according to the arrival times of the information, the framework and functions of multi-layer fault diagnosis system is presented in detail. After a disturbance occurs, the suggested system could realize disturbance identification, fault element diagnosis and detailed post-fault analysis in succession at different time frames with the information coming, which fits the needs of operators well. © 2007 IEEE.

关键词： Information systems

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Damping low-frequency oscillation in AC/DC power systems based on multi-operation modes

Damping low-frequency oscillation in AC/DC power systems bas...

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2006 International Conference on power system Technology, powerCON2006

作者： Yanfeng, Ma Zhao, Shuqiang Gu, Xueping Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Ministry of Education Baoding 071003 Hebei China

ISBN: (纸本)1424401119

PSS and DC modulation (DCM) controllers are effective in suppressing low frequency oscillations of AC/DC mixed power systems, but controllers designed by conventional method for a certain oscillation pattern of a given operation mode maybe have a negative effect on other patterns, moreover, when the operate mode is changed, the damping effect becomes bad, so the coordination of parameters which are fit for multi-operation modes is a pivotal problem. Locations of controllers are determined by participation matrix, and parameters are coordinated by improved GA combined with sensitivity matrix and features of AC/DC mixed power systems. The example shows that parameters of controllers chosen by participation matrix and improved GA can have a good effect on damping low-frequency oscillations and have strong applicability. © 2006 IEEE.

关键词： Electric power systems

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power system dynamic simulation validation based on similarity theory and analytical hierarchy process

Power system dynamic simulation validation based on similari...

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2006 International Conference on power system Technology, powerCON2006

作者： Han, Dong He, Renmu Ma, Jin IEEE Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University 102206 Beijing China

ISBN: (纸本)1424401119

Simulation assessment of error and veracity is the precondition in power system dynamic simulation validation that is directly related to power system stability. Own to the applications of Wide Area Measurement system (WAMS) that could provide synchronous measured information of power grid, it is possible to assess dynamic simulation. Based on the principles of similarity theory and Analytical Hierarchy Process (AHP), this paper proposes general assessment method on amplitude similarity degree of simulation and its relative error criterion by analyzing the characteristics of power system dynamic stability and variables. This method could not only systematically reflect the similarity degree of whole system and every time period, but also provide objective quantitative information and reference for further model validation and parameter correction. A case study is presented to verify the proposed method on the basis of the measured data from WAMS of certain power grid. © 2006 IEEE.

关键词： Circuit simulation

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Novel modeling and control of doubly-fed variable-speed constant-frequency wind power generator

Novel modeling and control of doubly-fed variable-speed cons...

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33rd Annual Conference of the IEEE Industrial Electronics Society, IECON

作者： Qihui, Liu Fang, Yu Jianhua, Zhang Key Laboratory of Power System Protection Dynamic Security Monitoring and Control under Ministry of Education North China Electric Power University Beijing 102206 China

ISBN: (纸本)1424407834

Reasonable modeling and control is of significance for theory study and practical operation of doubly-fed variable speed constant frequency (DFVSCF) wind power generator. Two sorts of simulation models called no-load model and generation model were obtained through linearization and discretization of the state equations of doubly-fed induction generator (DFIG), which was derived from the DFIG model in synchronously rotating reference frame. Both models work in coordination one after another to achieve the whole simulation of DFIG before and after grid-connection. Based on the field-oriented vector control technique, the decoupling control of output power of DFIG, together with grid synchronization, was investigated. The maximum power point tracking (MPPT) was realized by control of DFIG active power. The simulation results, which are highly consistent with the experiment results, verify the validity and correctness of the theoretical analysis and control strategy proposed by this paper. ©2007 IEEE.

关键词： Equations of state

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A novel algorithm for discrimination between inrush currents and internal faults based on equivalent instantaneous leakage inductance

A novel algorithm for discrimination between inrush currents...

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2007 IEEE power Engineering Society General Meeting, PES

作者： Ma, Jing Wang, Zengping IEEE Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China

ISBN: (纸本)1424412986

A novel scheme based on equivalent instantaneous leakage inductance (EILI) to distinguish inrush currents from internal fault currents in power transformers is proposed, which is derived from the circuit differential equation. First, the EILI that represents different characteristics between the inrush current and an internal fault is defined, and its calculation methods and the criteria of two-winding and three-winding transformers are derived. This method does not require B-H curve data and the parameters of leakage inductances obtained from the transformer manufacturer. A total of 147 experimental cases verify that the EILI calculated in real time is able to clear internal fault even light fault rapidly and correctly. © 2007 IEEE.

关键词： Fault tolerance

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A new adaptive method to identify inrush using grille fractal

A new adaptive method to identify inrush using grille fracta...

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2007 IEEE power Engineering Society General Meeting, PES

作者： Wang, Zengping Ma, Jing IEEE Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Province China

ISBN: (纸本)1424412986

This paper presents a novel scheme based on grille fractal for distinguishing between inrush currents and internal fault currents in transformers, which is derived from the singularity detection in the waveforms. First, differential currents are analyzed on the basis of grille fractal (GF). Noises are then filtered by use of the adaptive generalized morphological filter (AGMF). In a total of 158 experimental cases, the inrush current is characterized by the drastic variation, but the faulty current is kept almost constant. The experimental results indicate that the proposed technique is stable and reliable during discrimination between internal faults and magnetizing inrush currents, and saturation of current transformers (CTs). © 2007 IEEE.

关键词： Electric fault currents

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Parameters optimization of VSC-HVDC control system based on simplex algorithm

Parameters optimization of VSC-HVDC control system based on ...

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2007 IEEE power Engineering Society General Meeting, PES

作者： Chengyong, Zhao Xiangdong, Lu Guangkai, Li IEEE Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Baoding 071003 Hebei Provinece China

ISBN: (纸本)1424412986

The performance of VSC-HVDC system depends on the parameters of control system, and usually PI controllers have been used to adjust system to fulfill desired objectives. However, the optimization methods for PI controllers' parameters of VSC-HVDC system are very few up to now. A control strategy based on direct analytic expression for VSC-HVDC is presented and the corresponding control system is designed. Simplex algorithm and system objective function are adopted to optimize the PI parameters for single- and multi-objective VSC-HVDC system on the basis of the control strategy. Simulation results in PSCAD/EMTDC software testify the performance of VSC-HVDC control system with optimized PI parameters and show that the controllers with the optimized PI parameters can effectively control VSC-HVDC system. Advantages of the control system with optimized parameters, such as precise control, quickly responding time and strong robustness have been testified by step response. © 2007 IEEE.

关键词： HVDC power transmission

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Imitation of the characteristics of the wind turbine based on DC motor

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Frontiers of Electrical and Electronic Engineering in China 2007年第3期2卷 361-367页

作者： LIU Qihui HE Yikang ZHAO Rende Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control under Ministry of Education North Electric Power UniversityBeijing 102206China College of Electrical Engineering Zhejiang UniversityHangzhou 310027China

This paper analyzed the operating principles and power and torque characteristics of the wind turbine and the direct current motor (DC motor), and investigated the operating characteristics of the wind turbine compared to that of the DC motor. The torque imitation scheme, which has good performance and high feasibility, together with the whole wind turbine imitation system, was provided. The wind turbine imitation system includes not only a hardware platform composed of PC, data-collection board and thyristor-based velocity-regulator, but also monitor software of wind turbine imitation. The experimental results of different occasions verify the correctness and feasibility of the wind turbine imitation scheme proposed in this paper, which provided a valid idea for wind turbine imitation and investigation of wind power generation techniques in the laboratory.

关键词： wind turbine DC motor imitation character-istics wind power generation

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New criterion for transformer differential protection to rapidly identify transferring faults

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Dianli Xitong Zidonghua/Automation of Electric power systems 2007年第20期31卷 61-64+107页

作者： Yang, Qing Zheng, Tao Xiao, Shiwu Huang, Shaofeng Liu, Wanshun Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Beijing 102206 China

Current transformer saturation has always been one of the major problems of degraded reliability of the transformer differential protection. The ratio restraining differential characteristic can enable the transformer protection to be immune to the mal-operation in the external fault to some extent. But how to unblock the differential protection rapidly for the transferring fault form an external one to an internal one has become a new problem. This paper presents a new method of unblocking the differential protection for the transferring fault. In the method proposed, current comparison is made between he maximal value of the integrated negative phase sequence component of the current on the two sides of a transformer and the integrated negative phase sequence component of the differential current. Based on the current comparison results, the method proposed can not only accurately identify the internal fault and the external one, but also the transferring fault developed from the external fault to the internal one. Simulation results of ATP validate the effectiveness of the method proposed.

关键词： Transformer protection

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