Direct current line pilot direction protection method and system based on inductive energy polarity

The invention relates to a direct-current line pilot direction protection method and system based on inductive energy polarity, belongs to the technical field of relay protection, and solves the problems that the direct-current line protection in an alternating-current and direct-current series-parallel system is poor in transition resistance resistance when an internal fault occurs, maloperation is easy to occur when an external fault occurs, and the like. The method comprises the following steps of: determining a frequency band range when the comprehensive impedance in the alternating-current and direct-current hybrid system is inductive, and a minimum value and a second minimum value of an angular frequency in the frequency band range; collecting voltage and current of the positive pole direct current line on a rectification side and an inversion side before and after the fault; filtering the voltage and the current to obtain the current and the voltage when the angular frequency is between the minimum val