Protective layer grounding fault detection method, positioning method, detection system and positioning system

The invention discloses a protective layer grounding fault detection method, a positioning method, a detection system and a positioning system. The protective layer grounding fault detection method method comprises the following steps: acquiring a reference current waveform; acquiring a head end current waveform and a tail end current waveform of each section; taking the reference current wave as a zero phase, and based on the head-end current waveform and the tail-end current waveform, obtaining a first phase difference between the head-end sheath current and the reference current and a second phase difference between the tail-end sheath current and the reference current; adopting a fast Fourier transform method to obtain a current vector of a head-end protective layer and a current vector of a tail-end protective layer; and performing difference calculation on the current vector of the head-end protective layer and the current vector of the tail-end protective layer, and if the difference is greater than a