Online monitoring and early warning method and system for abnormal discharge of direct-current power transmission line

The invention relates to the related technical field of online monitoring of power transmission lines, in particular to an online monitoring and early warning method and system for abnormal discharge of a direct-current power transmission line. The method comprises the following steps that a first sampling rate acquisition circuit acquires traveling wave current of a power transmission line at a first sampling rate, after suspected abnormal discharge is judged, a second sampling rate acquisition circuit is started to acquire the traveling wave current, the traveling wave current acquired at a second frequency is uploaded, and the first sampling rate is smaller than the second sampling rate; the waveform information of the uploaded traveling wave current is processed to identify all risk towers; and all the risk towers are judged to determine the risk tower with abnormal discharge. The problems that in the prior art, a large number of monitoring devices need to be installed for long-distance transmission of a