Influence of AC voltage on the positive DC corona current pulses in a wire-cylinder gap

In the development of hybrid HVDC and HVAC transmission lines, the study of radio interference is an important issue. Positive corona current pulses from high voltage transmission lines are the main source of radio interference. In this paper, the design of a wire-cylinder gap electrode system is presented to study the influence of AC voltage on the characteristics of positive corona current pulses. The study shows that the mode of the current pulses is different from that of either DC or AC corona discharge. Waveform parameters of the pulses, such as rise time, half wave time, duration time, repetition rates, average amplitude, and time intervals of secondary pulses are all statistically analyzed in this study. The empirical formulas for the repetition rates with different AC voltages are presented. A theoretical explanation based on an ion cloud model is given to reveal the mechanism behind the influence of AC voltage on positive corona discharge. The experimental results could provide some references for the prediction of radio interference from hybrid AC/DC transmission lines.