Online monitoring method and device for grounding resistance of power transmission line tower and power transmission network

The invention discloses an online monitoring method and device for grounding resistance of a power transmission line tower and a power transmission network. The online monitoring method for the grounding resistance of the power transmission line tower comprises the following steps: acquiring current signals at two sides of different power transmission line towers; determining whether the power transmission line fails or not according to the directions of the current signals on the two sides of the same power transmission line tower; determining a fault interval where the fault position is located according to the direction change sequence of the current signals on the two sides of the different power transmission line tower; wherein the fault section is located between the two transmission line towers of which the current signal directions are preferentially changed; determining a fault position according to the time difference of the current signal direction changes of the power transmission line towers at t