Transmission line fault travelling wave ranging method based on VMD (variational mode decomposition) and soft morphology

The invention discloses a transmission line fault travelling wave ranging method based on VMD (variational mode decomposition) and soft morphology. The method comprises steps as follows: firstly, voltage data of two ends after fault occurrence is collected, primary fault travelling wave signals are cut off, and data 3 ms after the fault is selected; secondly, fault travelling waves are subjected to phase-mode transformation; thirdly, line model components are subjected to VMD, white noise is automatically filtered out in a decomposition process, an IMF1 component set obtained through the decomposition contains fault information, then IMF1 components are processed with a soft morphological edge detection method, and a travelling wave range arrival moment can be clearly obtained by combining advantages of VMD and soft morphological edge detection. Compared with conventional fault location method, the travelling wave based fault location method has the advantages that the travelling wave range detection effect i