Research on Discharge Characteristics and Altitude Correction of Typical Air-gap in 500kV High-Altitude Substation

In order to reduce the construction cost of 500kV substation and improve the design reliability, it is necessary to study the discharge characteristics of typical air gaps. In this paper, the discharge tests of bundle conductor to herringbone frame air gap of UHV substation were carried out in Beijing (0m above sea level, 0m a.s.l) and Tibet (4300m a.s.l). The discharge characteristic curves of AC, switching impulse and lightning impulse were obtained. Then, using the existing altitude correction methods, the calculated value and the tested value of altitude correction factor were compared and analyzed. Finally, using the linear interpolation method, the discharge characteristic curve in the range of 1000m-5000m above sea level was obtained, and the minimum air gap distance was recommended. The research results can be used to guide the engineering design of UHV substation in high altitude areas, and it is also great significant to the design, construction and operation of other power transmission projects in high altitude areas.