Fast fault line selection method based on increment coefficient of power frequencies before and after switching of medium-value resistor

The invention provides a fast fault line selection method based on an increment coefficient of power frequencies before and after switching of a medium-value resistor. The method includes the following steps: when a distribution network system, which is connected in parallel to a medium-value resistor by an arc suppression coil, has a single-phase earth fault, analyzing fault characteristics of azero sequence current and their difference of the medium-value resistor before and after switching, using half cycles before and after the switching of the medium-value resistor as data windows, extracting power frequency components of the zero sequence current by using wavelet transform, calculating the power frequency components of the zero sequence current based on a half-cycle integral algorithm, constructing increment coefficient K values according to the ratio of integral values of the power frequency components of the zero sequence current before and after the switching, and finally determining fault line selec