Method for monitoring electric leakage of alternating current system loop for transformer substation

The invention particularly relates to a method for monitoring electric leakage of an alternating-current system loop for a transformer substation, and the method comprises the steps: respectively installing residual current transformers (RCTs) at the head and tail ends of a radial branch of the alternating-current system loop, and then installing N residual current transformers in the middle of the radial branch, the method comprises the following steps: naming all residual current transformers, setting the current sensed by the head-end residual current transformer as a head-end induced current, and setting the current sensed by other residual current transformers as other induced currents; then superposing two square waves with different frequencies on the head-end induction current and other induction current to form judgment signals, determining the phase difference between the head-end induction current and other induction current according to the phase difference between the judgment signals, and adjust