Advanced method for the insertion time of the closing resistor based on the pre-breakdown characteristics

Firstly, this paper analyzes the risk of harmonic overvoltage caused by inrush current, and reveals the fundamental reason of overvoltage by combining the standing wave effect and resonant effect on transmission lines. Then, the shortage of the existing inrush current inhibition strategy through the phase selection making and closing resistor is analyzed. Based on the closing characteristic and the time dispersion of mechanical action of circuit breakers, a method to calculate the optimal angle of phase selection making in transformer considering pre-breakdown characteristics and a quantitative evaluation method of the closing resistor insertion time are proposed. Finally, the methods proposed in this paper are applied to the commissioning test of Sichuan-Tibet Interconnection Project. Results show that the proposed method can accurately calculate the closing resistor insertion time and inrush current and find the optimal angle of phase selection making, with less than 5% error, considering the action discreteness and pre-breakdown characteristics of breakers. The research results have important theoretical and practical significance for suppressing harmonic overvoltage in weak-connection power system and enhancing power system operation reliability.