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Kunming, China

Xiong X.-F.,Chongqing University of Technology | Gong X.-F.,Chongqing University of Technology | Wang Y.-X.,Yunnan Power Company
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2013

Meteorological factors will cause the transmission line fault and affect the power system reliability prominently. The original reliability parameter model which considered the meteorological factors is improved, and it is pointed out that transmission lines in different geography have different average failure rate, and their corresponding three kinds of weather and the percentage of number of failures under the three kinds of weather also show great difference. Connection number is used to deal with the uncertainty of reliability original data and weather conditions. RBTS is evaluated with state enumeration method, and the reliability indices in form of connection number are obtained. The result shows that the uneven geography and meteorology will affect the reliability evaluation of the transmission system greatly, and the reliability indices in form of connection number also give the uncertain part, which proves the reliability of the proposed method. Source


Meng G.,Wuhan University | Meng G.,State Grid Electric Power Research Institute of China | Wen X.,Wuhan University | Deng W.,State Grid Electric Power Research Institute of China | And 3 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2013

In order to get the design foundation of 500 kV substations at high altitudes in China, we employed the up-and-down method to investigate the switching impulse and lightning impulse discharge characteristics of typical simulation frameworks of 500 kV substation at three altitudes (Wuhan 23 m, Xining 2 254 m, Dawu 3742 m) by combining with 500 kV Jiangtang transmission project in Yunnan Province. Switching impulse and lightning impulse discharge curves were obtained with phase-ground gaps of 3~6 m, and several altitude correction methods were used to calibrate and analyze the results so as to give the appropriate correction method for Jiangtang transmission project. The experiments show that the 50% lightning impulse voltages and 50% switching impulse voltages decline with increasing altitudes, but the trend and level of changes have notable differences. Meanwhile, the saturation 50% switching impulse voltage curve is more significant with increasing gaps. According to comparison among altitude-correcting methods, it is concluded that IEC 60071-2: 1996 is suited for correcting lightning impulses of 500 kV substations, and the correction method containing m factor is suited for correcting switching impulses in phase-ground gaps. Source


Meng G.,Wuhan University | Meng G.,State Grid Electric Power Research Institute of China | Wen X.,Wuhan University | Deng W.,State Grid Electric Power Research Institute of China | And 3 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2013

Phase-to-phase switching impulse discharge characteristics play an important role in the design of substation equipment. In order to get the design foundation of 500 kV substations at high altitudes in China, taking into account of 500 kV Jiantang transmission project in Yunnan Province, we practically simulated and tested phase-to-phase switching impulse discharges between flexible buses or grading rings and a typical electrode pair in 500 kV substations. The experiments were performed in 3 areas at different altitude: Wuhan 23 m, Xining 2254 m and Dawu 3742 m, in which phase-to-phase switching impulse discharge curves for gaps of 5~8 m were obtained using the up-and-down method. The influences of voltage distribution coefficients on the gas insulation of phase-to-phase gaps were analyzed, and the experimental results were corrected for the altitudes and then comparatively analyzed. It is concluded that the discharge voltage of air gap decreases sharply with increasing altitude, meanwhile, U50, the 50% switching impulse discharge voltage of phase-to-phase insulation, increases with the voltage distribution coefficient. According to a comparison among several altitude-correction methods, the method in IEC 60071-2-1996 and the m-factor involved altitude-correction method are suggested for phase-to-phase switching impulse's altitude corrections of grading rings and flexible buses in 500 kV substations at high altitudes, respectively. Source


Zhao Z.,Kunming University of Science and Technology | Gao L.,Kunming University of Science and Technology | Li C.,Kunming University of Science and Technology | Li Y.,Kunming University of Science and Technology | Peng Q.,Yunnan Power Company
Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument | Year: 2016

In order to discover the possible abnormal temperature rise of oil immersed power transformer during long-term continuous operation, it is necessary to monitor and judge the hot spot temperature of the transformer. Using the insulation and high voltage withstanding properties of fiber Bragg grating (FBG) sensing technology, the temperatures of the transformer winding and transformer oil are monitored. The thermoelectricity analogy method is used to build the thermal model of the heat exchange between transformer winding and transformer oil; the position and temperature of the transformer winding hot spot are analyzed. The analysis results show that, under the rated power condition, the winding hot spot is located at 45cm to the bottom of the transformer winding and the hot spot temperature is about 66.8 ℃. While under the power of 1.3 times of the rated power, the hot spot is located at 40cm 45cm to the bottom of the transformer winding, and the hot spot temperature is about 71.5 ℃. © 2016, Science Press. All right reserved. Source


Zhu X.,Northeast Dianli University | Yu B.,Henan Electric Power Company | Zhang W.,Yunnan Power Company
Proceedings 2011 International Conference on Mechatronic Science, Electric Engineering and Computer, MEC 2011 | Year: 2011

Based on the complex network theory, this paper proposes a weighting parameters based on the voltage and reactance of the transmission lines, and a new method to measure the vulnerability of power grid through the betweenness index. This paper gives a new weight formula and a algorithm to identification of vulnerable lines. The analysis has been carried out on the IEEE5bus system, which confirms the efficacy and practical of the method. © 2011 IEEE. Source

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