Zou Jianhua1,Kang Ning1,Li Cheng1,Wang Hong2
(1. School of Electronics and Information Engineering, Xi'an Jiaotong University, Xi'an 710049, China;
2. China Yangtze Power Co. Ltd, Yichang 443002, China)
Abstract: In order to research
the generating mechanism of very fast transient overvoltage (VFTO) that is caused by the
operation of isolator in gas insulated substation (GIS), a method of detecting ¡®exciting
mode¡¯was used here. The method of¡®exciting mode¡¯was very useful for catching the
main factors which influence VFTO. Up to now, two kinds of exciting mode¡¯were
discovered. One was the effectiveness of the capacitance of bushing, and the other was the
change of conductor¡¯s surge impedance. Thus, a new method to depress VFTO was proposed,
i.e. a section of conductor with lower surge impedance was added at the terminal of GIS.
The analysis shows that the proposed method is very effective for depressing VFTO.
Keywords: gas insulated substation; very fast transient overvoltage; exciting mode;
depression