Device and method for monitoring arrester resistance current by introducing unconventional potential transformer (PT)

The invention discloses a method and a device for monitoring arrester resistance current by introducing unconventional PT. Firstly, the monitoring device accesses sampled value (SV) messages of merging units (MU), decodes the SV messages, detects the time of zero crossing point of busbar voltage, calculates the channel delay accurately by relying on an external synchronous clock, and restores sinusoidal waveform of the busbar voltage accurately. Secondly, the monitoring device collects leakage current sensor information mounted on a grounding wire of an arrester, and decomposes the leakage current of the arrester into resistance current and capacity current. Thirdly, the monitoring device determines the operation condition of the arrester based on the change rate of the resistance current and the ratio of the resistance current value in the arrester leakage current. According to the method and the device for monitoring arrester resistance current, the problem that some online monitoring devices cannot introduce busbar voltage signals for calculating the arrester resistance current when the busbar voltage is digital signals in intelligent substations or digital substations is solved effectively, defects of early aging, insulation hidden dangers and the like of arresters can be found earlier, and application prospect in the market is broad.