Ground parameter real-time measurement algorithm after single-phase ground fault of power distribution network

The invention discloses an earth parameter real-time measurement algorithm after a single-phase earth fault of a power distribution network, and the scheme is as follows: 1, carrying out the real-time sampling of a three-phase power supply voltage and a zero-sequence voltage of the power distribution network, monitoring whether the single-phase earth fault occurs or not, and carrying out the phase selection operation after the fault; and 2, after a single-phase earth fault of the power distribution network occurs, injecting a non-power frequency characteristic signal into the power distribution network, listing a time domain differential equation, filtering power frequency components in voltage and current signals by using a trigonometric function formula, constructing a differential equation only containing characteristic components, and calculating three-phase earth capacitance and transition resistance of the power distribution network after the fault through fitting. The earth parameter measurement algori