A method for detecting a
high impedance grounding fault based on
fault resistance nonlinear identification comprises the steps: collecting phase voltages of a detected
feeder line and an instantaneous value of a zero sequence current, respectively calculating a
correlation coefficient of each phase
voltage and the zero sequence current, if the
correlation coefficient of one phase
voltage and the zero sequence current is larger than a threshold value R, fitting a
current voltage characteristic curve composed of the phase
voltage and the zero sequence current in a sectional and linear mode through a least square method, accordingly, calculating and obtaining a coefficient, namely, a
fault resistance nonlinear coefficient which can effectively present characteristics of the
high impedance grounding fault according to the slope of each fitting straight line, judging whether a suspected
high impedance grounding fault exists by comparing the
fault resistance nonlinear coefficient and the threshold value, continuously detecting the lasting time of the suspected high impedance grounding fault, and if the lasting time exceeds
delayed time, finally judging that the high impedance grounding fault occurs. Compared with a detecting method based on a
harmonic wave, the method achieves high sensitivity, and compared with a method simply based on the
time domain amount, the method achieves a better
noise resisting capacity.