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Nanchang, China

Hu J.,China Electric Power Research Institute | Guo R.,Maintenance Company | Pei C.,Taiyuan Electrical Power Company of SGCC | Min X.,China Electric Power Research Institute | And 2 more authors.
Gaodianya Jishu/High Voltage Engineering | Year: 2013

Taking the characteristics of ultra-high voltage(UHV) transmission line into consideration, we established conductor-insulator strings coupled finite element models of single-span and three-span lines, then calculated and compared galloping of UHV transmission lines with the models. The results show that a relatively large difference exists between the calculation results of the single-span and three-span models (the average difference rate is 10.9%), when the left and right spans have the same height and no matter the lines are triangularly-arranged or horizontally-arranged; however, when the left and right spans have a height difference more than 50 meters, the calculation results of the single-span model well agree with those of the three-span model (the average difference rate is 4.9%). The fixed constraint of single-span model produces a strong constraint force, meanwhile, the large height difference in three-span model enhances the constraint of middle span, leading to calculative conditions close to the fixed constraint of single-span model, so there is good agreement between the results of the two models. It is concluded that when a large height difference exists between left and right spans, single-span model can replace three-span model to calculate and emulate galloping, so the time cost of computing can be reduced without affecting the deviation the calculation results.

Liu Y.,Tianjin University | Du B.,Tianjin University | Lu Y.,Beijing Electrical Power Research Institute | Yin Z.,Maintenance Company
Gaodianya Jishu/High Voltage Engineering | Year: 2014

In order to investigate the influence of disastrous fog conditions on the reliability of insulators, taking silicon rubber insulators (SRIs) as the specimens, we analyzed the adsorption and condensation of water droplets and how they affected the flashover voltage of SRIs with different contaminations and different wet conditions, by using a visible experimental system and artificial atmospheric experimental devices. By establishing the relationship among salt-fog contamination degree, relative humidity, adsorption and condensation on SRI surface, and droplet distribution characteristics (including area, size, and box dimension), we obtained the patterns of how these characteristic parameters influence the flashover voltage of SRI. It is shown that, with increasing relative humidity and contamination level, the numbers of both medium-sized (1 mm≤max diameter Dmax<2 mm) and big-sized (Dmax≥2 mm) droplets increase obviously, the number of small-sized (Dmax<1 mm) droplets decreases slightly, and the amount of droplets in total increases. The increase of droplet distribution's box dimension illustrates that the distribution gets more dispersed and more complex. Though the flashover voltage of insulator is not directly reflected by the amount variation of adsorbed droplets on insulator surface, it decreases with the increase in box dimension of droplet distribution.

Wang X.,Jiangxi Electrical Power Company | He P.,Maintenance Company | Liu Y.,Jiangxi Electric Power Research Institute | Yan N.,Jiangxi Electric Power Research Institute
Gaoya Dianqi/High Voltage Apparatus | Year: 2014

An accident of a 500 kV hybrid gas insulated switchgear (HGIS) in a 500 kV substation is analyzed. Disassembly inspection of the HGIS reveals that the basin insulator for VT chamber has been burnt into pieces due to discharge, and the poor quality of the basin insulator caused this accident. Subsequently, this malfunctioned equipment is replaced, and chemical and electrical tests are conducted for the basin insulators in same batch. In addition, some countermeasures are suggested.

Gong J.,Northeast Dianli University | Ren D.X.,Northeast Dianli University | Zhou C.,Qinghai Hainan Electrical Power Supply Company | Ma G.Q.,Maintenance Company
Applied Mechanics and Materials | Year: 2013

Take advantages of concrete to improve the stiffness of fiber reinforced composite material(GFRP), reference to the existing dimensions of concrete-filled steel tube pole, applicate GFRP-concrete structure in 35 kV transmission line. Change the various parameters of the poles in ANSYS, compare the maximum deformations and the maximum stresses of GFRP tube-concrete pole and concrete-filled steel tube pole. Results show that different parameters have different impacts on the mechanical properties of the poles, suitable parameters of GFRP tube-concrete pole were got and the technical specifications of the application of GFRP in various voltage levels should be perfected. © (2013) Trans Tech Publications, Switzerland.

Xiong Q.,Hunan University | Luo A.,Hunan University | Wang X.,Maintenance Company | Li X.,Hunan University | And 2 more authors.
Dianli Xitong Zidonghua/Automation of Electric Power Systems | Year: 2014

There exists 100 Hz ripple in the DC side capacitor voltage of the cascaded static var generator (SVG), and the filter circuit is often used in the detection of DC side voltage. Mainly the effect of the filter circuit on the stability of the DC side voltage is studied. The DC side voltage closed-loop control model containing the filter circuit is established according to the principle of the energy balance. An analysis of the stability of the control model shows that the necessary condition for the robust stability of the system is to obtain the regulator integral time constant greater than the filter time constant. A 13-level SVG experimental prototype is built. Experimental results under 220 V and 3 000 V voltage respectively have verified the correctness of the stability analysis. © 2014 State Grid Electric Power Research Institute Press.

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