Time filter

Source Type

Hu N.,University of Sichuan | Li X.,University of Sichuan | Li K.,University of Sichuan | Mu Z.,Chongqing Jiangbei Power Supply Bureau | Zhu R.,University of Sichuan
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

With the rapid development of synchrophasor based wide area monitoring systems (WAMSs), measurements from the phasor measurement units (PMUs) can be used for online identification of the low frequency oscillations in power systems. To solve the problem that colored Gaussian noise produced by low pass filters may impact the accuracy of oscillation mode indentification, this paper proposed a modified matrix pencil method based on fourth-order mixed mean cumulant (FOMMC) for oscillation mode identificaion. Substituting the sampled signal by its fourth-order mixed mean cumulant sequence along the diagonal line, the method can reduce the impact of the noise effectively. The simulation result shows using the proposed method, the dominant oscillation modes can be identified in the environment with additive colored Gaussian noise. © 2013 Chinese Society for Electrical Engineering.

Lu Z.,Chongqing University | Liu J.,Chongqing University | Zheng L.,Chongqing University | Ma Z.,Chongqing University | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2010

A novel input-series output-series high gain Boost converter was proposed in this paper. Operation principle and property of this converter were analyzed. The new topology was composed of two identical high gain subtopologies with input-series and output-series connection. As the Cf1 and Cf2, the new topology not only had high voltage gain, but also automatically evenly could share current without any sensing when the duty cycle was greater than or equal to 0.5. Compared with the traditional two phase interleaved Boost converter, the ripple of the inductor current, the ripple of the input current and the voltage stress of the switches were reduced because of the double-series structure of the new topology. Consequently, the new topology is very suitable for the application (for example, the fuel cell power system) in which it has low input voltage but high output voltage. Finally, the experiment was built to verify the theoretical analysis. © 2010 Chinese Society for Electrical Engineering.

Feng W.,Chongqing University | Liu G.,Chongqing University | Liao Y.,Chongqing Jiangbei Power Supply Bureau | Zhao W.,Chongqing University
Journal of Information and Computational Science | Year: 2013

Clustering is an efficient way of network topology management, and the hierarchical structure obtained by clustering algorithm can largely improve the performance of Mobile Ad Hoc Network (MANET). To better accommodate MANET, we propose a Multi-parameter Weighted Clustering (MWC) algorithm which takes into consideration three parameters: residual power, connectivity, and average mobility. We also designed different average mobility parameter for two typical MANET models, that is, Relative Stability (RS) for Random Walk Mobility (RWM) networks and Moving Correlation (MC) for Reference Point Group Mobility (RPGM) networks. Simulation results showed that the proposed algorithm has a better performance than HD and MOBIC in three aspects: topology simplicity, environment adaptability, and cluster stability. © 2013 Binary Information Press.

Lei Y.,Tsinghua University | Lei Y.,Chongqing Jiangbei Power Supply Bureau | Zhao Z.,Tsinghua University | Yuan L.,Tsinghua University | Lu S.,Tsinghua University
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2012

LCL filters are increasingly used in grid-connected photovoltaic inverters as the preferred option. Its inherent resonance character makes the damping strategy a hot topic for research. LCL filter, inverter and the grid are modeled and studied as a whole. The commonly used virtual resistor method of passive and active damping, the impacts of inverter's behavior and the grid stiffness on the damping effect are studied in detail. The results show that the non-ideal characteristics of the grid, the proportional gain and the control delay affect the damping properties the most. A hybrid damping method combining active and passive damping is proposed. The method can reduce the impact of control delay and is adaptable for grid change. Experimental results show its effectiveness. © 2012 State Grid Electric Power Research Institute Press.

Tang J.,Chongqing University | Xie Y.,Chongqing University | Zhang X.,Chongqing University | Zhou Q.,Chongqing Jiangbei Power Supply Bureau
Gaodianya Jishu/High Voltage Engineering | Year: 2012

Radio frequency (RF) measurement has become a hot issue for partial discharge detection. However, its application is hampered by the difficulty to establish a relationship between the RF measurements data and apparent discharge quantity. In this paper, on the basis of an experimental model of metal protrusion, the relationship between the results of RF measurement and pulse current method (IEC 60270) was investigated. The energy, double integration, peak voltage, peak-peak voltage and the area of RF signals were plotted versus either the apparent discharge quantity or the square of the apparent discharge quantity in order to evaluate the optimal regression curve. At the same time, the impact of voltage and the distance between protrusion and plate were also investigated. The results indicate that the optimal match to a linear regression curve can be gained by plotting the RF signal energy versus the square of the apparent discharge quantity. The variation of voltage has no significant impact on the regression curve; that is, data from different voltages match one line. However, when the distance between protrusion and plate is changed, the slope of the regression curve changes accordingly; the same energy corresponds to a bigger discharge quantity. The results are significant enough to be applied in the estimation of the discharge quantity by measuring RF partial discharge signals.

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