Atmospheric Conditions Correction for Positive Switching Breakdown Voltage of 1-m Rod-Plate Gap

As converter stations are increasingly constructed at high altitudes, how to reasonably select the minimum air spacing of converter station substation equipment has become an important issue for DC power transmission at high altitudes. In order to study the influence of air environment on switching impulse discharge characteristics of air gap at high altitudes, this paper conducts switching impulse discharge tests on 1 m rod-plate air gap under different air pressure, temperature, and humidity conditions, investigates switching impulse discharge characteristics of rod-plate air gap at high altitude, and compares and analyses differences in correction results of various discharge voltage correction methods. Studies have shown that air pressure, temperature, and humidity have an effect on air gap discharge voltage. Meanwhile, based on different atmospheric parameters, correction formulas are obtained for 1m rod-plate air gap discharge voltage, and the elevation correction coefficients of 1m rod-plate air gap at each altitude was obtained. The results of the study provide a reference for external insulation of equipment and its insulation fit in converter stations at high altitude.