METHOD FOR CALCULATING MINIMUM SWITCHING TIME OF CLOSING RESISTOR OF HIGH-CAPACITY MAIN TRANSFORMER

摘要

A method for calculating the minimum switching time of a closing resistor of a high-capacity main transformer. The method comprises the following steps: (1) calculating the time t₁ when a magnetizing inrush current of the first closed phase produces the maximum value after being switched on; (2) calculating the lag time t₂ when a magnetizing inrush current of the second closed phase produces the maximum value; and (3) calculating the minimum switching time t_all, where t_all = t₁ + t₂. By means of the method, the magnetizing inrush current of the main transformer can be suppressed under the conditions of high capacity and high remanence, thereby reducing the harmonic overvoltage risks of the weak-tie power grid that has the characteristics of long distance and small load.