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International Conference on Electric Utility Deregulation and Restructuring and power Technologies

作者： Yang, Xiaodong Zhao, Chengyong Hu, Jing Wang, Jing Yang, Liu Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing China

ISBN: (纸本)9781457703638

A three-terminal DC transmission system based on modular multilevel converter (MMC) is developed to solve the problem of power supply for distributed islands or cities. The system, with flexible features, may generate high quality output voltage and reduce construction costs and power losses in the converter stations. However, the three-terminal DC system based on MMC faces more complex situations in operation and its control strategies. In this paper, the mathematic model of three-terminal DC system based on MMC is deduced. Then according to the structure of MMC, a method of carrier phase-shift SPWM is introduced. As the system-level control, the decoupling controller for three-terminal DC system based on MMC is designed. A multi-point DC voltage control strategy based on DC voltage error method, which doesn't need communication between converter stations, is proposed to improve the system reliability. By simulation with PSCAD/EMTDC, the feasibility and effectiveness of the proposed model and control strategies are verified. © 2011 IEEE.

关键词： Voltage control

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Wide area measurements-based model validation and its application

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IET Generation, Transmission and Distribution 2008年第6期2卷 906-916页

作者： Ma, J. Han, D. Sheng, W.-J. He, R.-M. Yue, C.-Y. Zhang, J. Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education North China Electric Power University Beijing 102206 China Limited CNCRC Universal Plaza Chaoyang District Beijing 100016 China

Simulation veracity is very important to the plan and operation of a power system. Too optimistic a simulation will put the system at risk whereas too pessimistic a simulation will waste investments. Wide area measurements (WAMs), one of the fast developing technologies in recent years, could record the synchronized phasors in the whole power grid, which provides the possibility for simulation validation work. Recent contingency reproduction work worldwide has shown the inaccuracy of current digital simulation. Therefore simulation validation and model calibration are necessary to enhance simulation veracity. However, because of the complexity of the power system, it is difficult to find the erroneous ones among a large amount of components, which makes the simulation validation a very challenging problem. A new approach for WAMs-based simulation validation work is proposed. The proposed method is very simple and easy to be implemented in the available power system simulation software. Then, the trajectory sensitivity method is applied to the parameter calibration work. Real applications via the proposed methods in the big NE power grid of China are studied, which fully show the efficiency of the proposed methods. © 2008 The Institution of Engineering and Technology.

关键词： Computer software

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Effect of wind farm based-on wound rotor induction generator on transient characteristics of transmission grid

Effect of wind farm based-on wound rotor induction generator...

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2009 Asia-Pacific power and Energy Engineering Conference, APPEEC 2009

作者： Lin, Li Sun, Feng Yang, Yihan Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control North China Electric Power University Ministry of Education Beijing China

ISBN: (纸本)9781424424870

With rapid development of wind power generation, large capacity wind farms are connected into the transmission system. Comparing with traditional power plant, the transient characteristics of transmission grid including wind farm are worthy investigating. The wind farm based-on wound rotor induction generators (WRIGs) shares high market occupancy in China, but academic researches on this grid-connected wind generation are few. So in this paper, the transient characteristics of the power system, adding a WRIGs wind farm and adding a traditional power plant, are compared. Effect of a WRIGs wind farm on transient performances of transmission grid is discussed. And the control effect on transient stability, when the WRIGs wind farm participating in system control during system fault, is investigated. Finally, simulation results are validated by using CIGREB4-39 grid. It is concluded that the transient performance of WRIGs wind farm is better than that of traditional power plant. © 2009 IEEE.

关键词： Wind farm

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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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Research and development of an intelligent system dealing with alarm messages coming from regional power grid control centers

Research and development of an intelligent system dealing wi...

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International Conference on power system Technology (powerCON)

作者： Zhang, Xing Zhang, Haibo Key Laboratory of Power System Protection and Dynamic Security Monitoring North China Electric Power University Beijing China

ISBN: (纸本)9781424459407

In order to overcome the disadvantage that there are hardly any analysis functions on alarm messages in current EMS, an Intelligent Expert system which processes all alarm messages from the regional Grid Dispatching Center is designed and developed in this paper. When there is only one SCADA data source, the system receives and identifies real-time alarm messages from dispatching center, finds out and deletes the false alarm messages and then estimates the current state of power grid. If there is no fault but some abnormal warning information is generated by electrical equipments, the system analyses the abnormal warning information and suggests corresponding measures that dispatcher should take. If some fault has occurred, the system classifies the alarm messages and provides the necessary information for fault diagnosis after further processing. After the system is completed, it will improve the quality of surveillance and provide richer and more intelligent auxiliary decision support. ©2010 IEEE.

关键词： Expert systems

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The research on distributed dynamic power flow based on asynchronous iteration mode considering frequency change

The research on distributed dynamic power flow based on asyn...

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International Conference on power system Technology (powerCON)

作者： Xin, Baojiang Zhang, Haibo Key Laboratory of Power System Protection and Dynamic Security Monitoring North China Electric Power University Beijing China

ISBN: (纸本)9781424459407

In modern power system, power systems are being interconnected into a unified system. The structure of the power grid is more and more complex, and the relation between different regional power grids is more closed. In order to achieve a joint power grid scheduling, incident handling and fault simulation, objectively, the control centers are required to use distributed algorithm. But the distributed Energy Management system (EMS) and Dispatcher Training Simulator (DTS) used now are not mature and the frequency changes are not considered in the distributed algorithms. This makes impossible to obtain an accurate simulation of the actual power system operation status in the distributed EMS/DTS. Because the dynamic flow algorithm can reflect the actual system more exactly, a new method called distributed dynamic power flow based on asynchronous iteration mode considering frequency change is proposed in this paper. The whole idea of the algorithm is given. The generator unit in dynamic power flow, considering frequency changes, can be modeled in coordinate layer and used to calculate frequency changes and the power sent to the network. The network modeled in coordinate layer and subsystems, is used to calculate power flow and unbalance power of the interconnected system. By a dozen times iterative solution between generator unit and network unit, the unbalanced power are distributed in generator and load nodes finally. In this article, we take the IEEE 9 node system as an example to authenticate this method. The simulation results are the same as the real ones hence showing that the new algorithm is real and effective. ©2010 IEEE.

关键词： Energy management systems

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Characteristic analysis of UHV secondary arc current under different power transmission

Characteristic analysis of UHV secondary arc current under d...

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2009 Asia-Pacific power and Energy Engineering Conference, APPEEC 2009

作者： Zhou, Lixia Zhang, Huiyuan Wen, Jun Xiao, Xiangning Key Laboratory of Power System Protection and Dynamic Security Monitoring North China Electric Power University Beijing China

ISBN: (纸本)9781424424870

Along with the enhancement of voltage level, harmful affect of the secondary arc current to the system becomes more and more serious. The transmission power of the lines is one of factors that influence the secondary arc current obviously. The voltage distribution along the transmission line will changes according to the different transmission power, which will lead to the variation of the induction component from the sound phases when the fault occurs. In this paper, the quadric-mode transformation is adopted to establish the mathematic model of secondary arc current in the double-circuit transmission line. According to the variation of power transmission, the secondary arc current of different fault point is calculated. The results indicate that secondary arc current is influenced much by the line transmission power, and the variation trend changes along with the fault point. When the fault occurs in head or terminal of the line, the secondary arc current may becomes larger along with the increasing of the transmission power, thus effective suppress measurements must be taken. © 2009 IEEE.

关键词： power transmission

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Iterative prony method based power system low frequency oscillation mode analysis and PSS design

Iterative prony method based power system low frequency osci...

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2005 IEEE/PES Transmission and DistributionConference and Exhibition - Asia and Pacific

作者： Hu, Guoqiang He, Renmu Yang, Huachun Wang, Peng Ma, Rui Key Laboratory of Power System Protection and Dynamic Security Monitoring and Control Ministry of Education Beijing China Changsha University of Science Technology

ISBN: (纸本)0780391144

This paper presents an identification method based on the iterative Prony to identify transfer function and configure PSS parameters using residue way. The iterative Prony is a very useful method to acquire power system oscillation modes, by which the system eigenvalue, oscillation frequency, amplitude, damping and relative phase can be directly estimated using the response of given input signals. Considering the influence of input signal on output signal, the iterative Prony can acquire the transfer function of power system, then, according to the corresponding residues we conducted coordinated setting of power system stabilizer (PSS) by residue method. The simulation results for two testing system examples prove that this proposal method is effective in the power system oscillation mode analysis and parameters determination of PSS, can improve eigenvalues of system and can enhance system damping after PSSs whose parameters are optimized by above method are built into power system. © 2005 IEEE.

关键词： Standby power systems

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