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Sun Y.,Shandong University | Chao W.,Qingdao Power Supply Company
Advanced Materials Research | Year: 2012

This paper first gives out the harmonic coupled equivalent model for the Thyristor Controlled Reactors (TCRs) and the converter. Then, the harmonic generating characteristics of the TCRs and the converter are investigated based on the proposed model. With the help of the equivalent model, the impact of each harmonic contribution component is quantified. Moreover, based on the characteristics analysis of the model, two simplified model are proposed which are useful for simplifying the harmonic analysis of systems with TCRs and converters. Source


Zhou C.,Shandong University | Tian L.,Shandong University | Hou Y.,Shandong University | Qi W.,Qingdao Power Supply Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

A new method based on optimal voltage sag monitoring program is proposed to locate any type of fault on the transmission line when only voltage sag data are available. Firstly a 0-1 linear programming-based model is built to solve the problem of optimization allocation. The object of the optimization model is to minimize the number of the monitoring buses and the key constraint is to guarantee the observability of the whole system considering any type of fault (balanced or unbalanced). Then based on the optimal monitoring program, the fault position and faulted transmission line are estimated by implementing the least squares method. In this estimation, only the voltage sag magnitudes recorded at the limited optimal monitoring buses are available measurements. The performance of the proposed method is illustrated in an IEEE 39-bus test system, and the validity of the method is testified. ©2012 State Grid Electric Power Research Institute Press. Source


Liu D.,Shandong University | Li X.,Yanjin Power Supply Bureau | Zhao H.,Yanjin Power Supply Bureau | Zhong S.,Qingdao Power Supply Company
Dianwang Jishu/Power System Technology | Year: 2011

This paper, based on the platform of dispatching automation system, introduced the frame work, function modules and main characteristics of on-line stability and energy-saving comprehensive monitoring and early-warning system. Based on real-time collected data, stability and energy-saving comprehensive monitoring and early-warning system (SEMW) can display core power system state information, such as stability mode, stability index, the relative relations between stability and active-power loss as well as reactive-power compensation levels, and so on. Through this, the dispatcher can clearly understand power system running situation. SEMW is specialized in quick location of hidden power security dangers, automatic intelligent control and voice warning. With engineering implementation, SEMW can significantly improve the on-line stability and energy-saving comprehensive monitoring and early-warning capability, as well as realize the smart grid dispatching. Source


Li Z.,Shandong University | Han X.,Shandong University | Yang M.,Shandong University | Zhong S.,Qingdao Power Supply Company
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2011

Wind power is stochastic and is difficult to reflect its characteristics only by its expectation. Consequently the power grid risk is difficult to analyze. A new model based on the quantile regression analysis theory is proposed, in which a regression function is selected self-adaptively through support vector machine in each wind power fluctuation interval, and the interior point method is adopted to solve this model. The future wind power fluctuation interval analysis is realized. At last, the proposed method is used to analyze the output power of a wind farm in Yantai area power grid. The results show that the proposed method can give a better all-around description of wind power uncertainty, and provides a basis for the risk decision-making in the power system dispatch and control. © 2011 State Grid Electric Power Research Institute Press. Source


Peng M.,North China Electrical Power University | Zhao C.,North China Electrical Power University | Liu X.,Qingdao Power Supply Company | Guo C.,North China Electrical Power University
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2014

The capacitor voltage balancing of modular multilevel converter (MMC) determines the stable operation of MMC based high voltage direct current (HVDC) transmission system. When the number of sub-modules (SMs) is excessive, it requires a large amount of computation time, which poses a challenge to the design of the physical controller. To solve this problem, this paper proposed an improved capacitor voltage balancing method. The improved method grouped the SMs to reduce the computing quantity of sorting the capacitor voltages, and maintained the voltage balancing between groups by adopting the voltage balancing algorithm between groups. Then the optimization method inspired by the prime factorization principle is put forward. A MMC-HVDC model was developed in RT-Lab. The simulation results show that the improved method and the optimization method can both reduce the amount of computation and improve the simulation speed significantly with the balancing of capacitor voltages. All those results verify the effectiveness and feasibility of the improved method and the optimization method. © 2014 Chin. Soc. for Elec. Eng.. Source

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