Relay protection method, system and device of variable-speed pumped storage unit and medium

The invention relates to a relay protection method, system and device for a variable-speed pumped storage unit and a medium, and the method comprises the steps: collecting the analog quantity of rotor current and rotor voltage of the pumped storage unit; the frequency, the harmonic voltage and the harmonic current of the stator side of the pumped storage unit are collected; according to the analog quantity of the rotor current, the analog quantity of the rotor voltage, the frequency, the harmonic voltage and the harmonic current, the content of each harmonic wave in each cycle of the stator side is solved through a Fourier series decomposition method; the harmonic content of the stator side serves as the judgment basis of relay protection of the pumped storage unit, the problem that the variable-speed pumped storage unit lacks a complete and reliable relay protection scheme is solved, the stator side harmonic criterion is added on the basis of the traditional relay protection criterion, and the reliability of