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Dang J.,Central China Power Dispatching and Communication Center | Tang Y.,Nanjing Southeast University | Ning J.,Nanjing Southeast University | Fu X.,Jiangsu Electric Power Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2015

It is a serious problem that how to distribute large-scale electric vehicles coordinated charging load with the consideration of every single electric vehicle's charging demands and user intention. Firstly, a coordinated charging strategy for electric vehicles is proposed. Secondly, based on meeting the intention of every electric vehicle user, aiming at minimizing charging times of electric vehicles, charging arrangements for electric vehicles are decomposed to every electric vehicle with the historical driving distances and battery real-time states made as the weighted coefficient. Finally, practical data are applied to the simulation. The results show that with the consideration of application characteristic, charging state and charging times of every electric vehicle, the charging strategy of every electric vehicle is arranged based on the satisfaction of the charging load required. At the same time, the charging times are reduced. The distribution principle proposed is reasonable. ©, 2015, Power System Protection and Control Press. All right reserved.


Wu J.,Huazhong University of Science and Technology | Wen J.,Huazhong University of Science and Technology | Sun H.,Huazhong University of Science and Technology | Cheng S.,Huazhong University of Science and Technology | And 3 more authors.
Diangong Jishu Xuebao/Transactions of China Electrotechnical Society | Year: 2012

Flexible power conditioner (FPC) is a novel FACTS device which integrats both the characteristics of flywheel energy storage and the doubly-fed induction generator. It can perform multi-functions including energy storage, dynamic active and reactive power conditioning. A 380 V/4 kW FPC prototype is developed and detailed laboratory test of the dynamic operation characteristics of the prototype is performed in this paper. The test results show that the prototype can perform frequency conversion start without supplementary starting equipment, and exchange the active power and reactive power with the grid independently and quickly at both the sub-synchronous and super-synchronous operation states. The feasibility of the FPC is validated. Satisfactory characteristics dynamic operations are obtained.


Liu Z.,Huazhong University of Science and Technology | Yao W.,Huazhong University of Science and Technology | Wen J.,Huazhong University of Science and Technology | Li Y.,Central China Power Dispatching and Communication Center | Wang C.,Central China Power Dispatching and Communication Center
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2016

With the technique development of the governor system, the influence of governor system on low frequency oscillations (LFOs) has attracted more and more attention. The current research shows that the governor system not only can influence the damping characteristics of LFOs, but also will introduce a special very low frequency mode into the power system. This mode, called by frequency mode, has lower frequency than LFOs and would appear when the governor system is performed. In this paper, the influence of governor system on the damping characteristics of LFOs was investigated by using the torque analysis theory. Then the feature of the frequency mode and its influence on LFOs were mainly analyzed base on a 4-machine 2-area system. The analysis results show that frequency mode is a control mode of governor system and its damping ratio is significantly influenced by the parameters of the governor proportional integral derivative (PID) controller. When the governor system makes the damping ratios of LFOs become negative and the dead band is taken into account, the system LFO will gradually become equispacing oscillation if the damping ratio of the frequency mode is relatively strong, while the power LFO will appear like a beat frequency oscillation if the damping ratio of the frequency mode is relatively weak. Finally, simulation results of a practical inter-connected power system validate the effectiveness of the analysis results above. © 2016 Chin. Soc. for Elec. Eng.


Dang J.,Central China Power Dispatching and Communication Center | Tang Y.,Nanjing Southeast University | Song M.,Nanjing Southeast University | Ning J.,Nanjing Southeast University | Fu X.,Jiangsu Electric Power Company
Electronics and Electrical Engineering - Proceedings of the Asia-Pacific Conference on Electronics and Electrical Engineering, EEEC 2014 | Year: 2015

The wind-thermal-bundled power system transmitted by High Voltage Direct Current (HVDC) line has been an important development mode for large-scale wind power bases in northwest of China nowadays. In terms of the frequency stability problem of sending-end system caused by wind power fluctuation and some faults, the necessity for HVDC participating in frequency regulation is put forward. In this paper, the coordinated frequency control strategies of thermal units and HVDC link are proposed. Two cases are considered: the fluctuation of wind power and sending-end system faults. Simulations are carried out based on an equivalent wind-thermal-bundled power system to verify the effectiveness of the control strategies. © 2015 Taylor & Francis Group, London.


Zhao Q.,China Electric Power Research Institute | Zhang L.,China Power Engineering Consulting Group Corporation | Wang Q.,China Electric Power Research Institute | Li Y.,Central China Power Dispatching and Communication Center | And 4 more authors.
Dianwang Jishu/Power System Technology | Year: 2011

The impact of power system load model on frequency stability of power systems is analyzed. Based on the practical measured data of primary frequency regulation in Central China power grid in 2009 and the measured data of generation unit trip of a certain domestic power network, the comparative research between experimental results and simulation results is performed. By means of adjusting load frequency coefficient, the correctness and effectiveness of load model and its fitting parameters are verified. Simulation results show that the load frequency coefficient adopted in domestic frequency stability calculation biases towards conservative.

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