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Zhang Y.,Zhejiang University of Technology | Zhao Z.,Zhejiang University of Technology | Weng G.,Zhejiang University of Technology | Lin T.,Wenzhou Electrical Power Bureau | Jin H.,Zhejiang University of Technology
Dianli Zidonghua Shebei/Electric Power Automation Equipment | Year: 2011

As the complexity and time-variability of low-voltage power line network are the key factors affecting the reliability of power line communication, a low-voltage power line channel characteristic model based on FPGA(Field Programmable Gate Array) is presented. Its real-time simulation system is designed and controlled by FPGA, which consists of four modules: input pretreatment, channel simulation, output pretreatment and noise. The power line communication real-time channel simulator is constructed with FPGA to meet the requirements of system for real-time performance and low cost. The hardware simulation platform is built for system test and results show its working speed reaches nanosecond level. Source

Zhang L.,Tsinghua University | Lin Q.,Wenzhou Electrical Power Bureau | Ding D.-W.,Tsinghua University | Gao W.-S.,Tsinghua University
Gaodianya Jishu/High Voltage Engineering | Year: 2011

The ultra-high frequency (UHF) electromagnetic waves signal contains a dominant mode TEM wave and high-order modes TE, TM waves when partial discharge occurs in the GIS. In order to analyze the attenuation characteristics of these three models of electromagnetic waves in GIS coaxial transmission pipeline, using the finite difference time domain method (FDTD), we constructed a coaxial waveguide system with matching models at the both ends, and placed the PD source inside one of the matching cones, then investigated the amplitude and energy change characteristics by simulating the three modes of UHF signals which were excited in the tapered matching model and propagate in the coaxial waveguide system. The simulation results show that when the UHF signal transmits in the coaxial waveguide system, the dominant mode TEM is a non-dispersive wave, and its ability to communicate with the probe-PD source is independent of the angle φ. In addition, high-order mode waves TE, TM wave is dispersive wave, that is, along with the frequency increases, the attenuation is gradually increased, for different transmission channels (different angle φ), the distortion of TM wave is greater than the TE wave, but the distortions of both are independent of frequency. Source

Zhao Y.,State Key Laboratory of Power Transmission Equipment and System Security and New Technology | Zhang X.,State Key Laboratory of Power Transmission Equipment and System Security and New Technology | Lin S.,Wenzhou Electrical Power Bureau
Chongqing Daxue Xuebao/Journal of Chongqing University | Year: 2013

Photovoltaic power generation is considered to be one of the most promising power generation forms. It is difficult to accurately assess the reliability of the photovoltaic system (PVS) for the volatility and intermittent of the light intensity. By analyzing PVS component failure modes and their impacts on PVS output power, the reliability model of PVS is built. Then the probability model of PVS output power is presented by considering both illumination uncertainty and PVS component random faults. According to the influence of components random faults outside the intentional islands on the reliability of load points inside the intentional islands, the concepts of repair zone, isolation zone and zero zone are defined. Furthermore, by considering the fail-operation of breaker and fuse, the concept for zone hierarchy is proposed, and the analytical formulas to calculate reliability indices of the load points inside the intentional islands are deduced. The application of the presented reliability evaluation model is clarified using a typical example to show the practicality and validity of the proposed approach. Source

Zhou D.,Zhejiang Electrical Power Test and Research Institute | Zhu C.,Zhejiang University | Li P.,Zhejiang Electrical Power Test and Research Institute | Zhao B.,Zhejiang Electrical Power Test and Research Institute | And 2 more authors.
Zhongguo Dianji Gongcheng Xuebao/Proceedings of the Chinese Society of Electrical Engineering | Year: 2013

The switching point of combined flux observer had a very important influence on the performance of observer. An analysis to the relationship among the switching point, system parameters and performance of the observer was made, and the optimal design method of switching point was given. As the optimal switching point would change as the system parameters changed, it caused a decline in performance of combined flux observer. For this problem, a method of switch point self-tuning was proposed. Combined with the optimal design method of switch point, the switch point of combined flux observer could be real-time online adjusted which improved the performance and accuracy of combined flux observer. © 2013 Chin. Soc. for Elec. Eng. Source

Shao B.-G.,Wenzhou Electrical Power Bureau | Xue T.,Pingyang Electrical Pwer Ltd Cmpany | Xia Z.-Y.,Wenzhou Electrical Power Bureau | Mei Z.-S.,Wenzhou Electrical Power Bureau | And 3 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

Through the analysis of an accident's reason of the generator group's fracture flashover protection, the paper indicates the problem of technical management and technical supervision of generator group's fracture flashover protection at present in our country. The paper also puts forward remedial measures and executive plan of the generator group's fracture flashover protection by the exposition of the theory of fracture flashover protection and combining with the founded problems and existed faults in the actual practice of the generator group's fracture flashover protection, and how to effectively keep away from the artificial mistakes. It has extremely practical referential significance. Source

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