The invention relates to a method for locating a single-phase grounding fault by adopting a
transient state travelling wave and an injection method, which is suitable for locating a single-phase grounding fault of a low-current grounding
system. The method solves the defects of a
single fault locating method, thereby improving the fault locating accuracy. The method comprises the following steps of: (1) sampling a zero sequence
voltage, and calculating and judging whether the zero sequence
voltage exceeds a setting threshold value or not; if the zero sequence
voltage exceeds the setting threshold value, showing that an
electricity grid has a single-phase grounding fault, and then executing the following steps; (2) judging a fault phase according to the voltage change law in a
system single-phase fault, then obtaining a phase voltage at the fault moment, and comparing the obtained phase voltage with 0.8up, wherein up is a
system phase voltage
peak value; (3) if the
wavelet analysis is carried out on a
transient state travelling wave
signal, determining the time
delta t for the travelling wave to go to and fro between a fault point and a
generatrix once, thereby calculating the distance from the fault point to the
generatrix; (4) and if a fault circuit is selected,
cutting the power of the fault circuit, injecting a pulse
signal to the fault
signal, carrying out
wavelet transform, detecting the reflected wave of the fault point, thereby obtaining
delta t, and then calculating the distance from the fault point to the
generatrix.