Method and device for detecting single-phase earth fault of power distribution network

The invention discloses a method for detecting a single-phase earth fault of a power distribution network, and the method comprises the steps: obtaining phase currents corresponding to all lines in the power distribution network, and the phase currents comprise a first phase current, a second phase current and a third phase current; respectively determining corresponding phase current break variables in each line, wherein the phase current break variables comprise a first phase current break variable, a second phase current break variable and a third phase current break variable; the Tanimoto similarity corresponding to the phase current break variable in each line is calculated, and the minimum value of the Tanimoto similarity in each line is determined; wherein the value of the Tanimoto similarity is in direct proportion to the waveform similarity of the corresponding two-phase abrupt change current; and under the condition that the minimum value of the Tanimoto similarity corresponding to any line is small