Power transmission line optical fiber differential protection data synchronization method and system suitable for distribution network

The invention discloses a power transmission line optical fiber differential protection data synchronization method and system suitable for a distribution network. The method comprises the following steps: acquiring local side sampling data of a local side line protection device and opposite side sampling data of an opposite side line protection device; calculating a sampling moment when the opposite-side sampling data corresponds to the local-side line protection device, and synchronously interpolating the local-side sampling data to the sampling moment to obtain interpolation data; performing differential protection calculation by using the interpolation data and the opposite-side sampling data, and determining whether a differential action condition is met or not; starting condition calculation is carried out by using the sampling data of the side, and whether starting conditions are met is determined; acquiring a differential permission signal of an opposite-side line protection device; only when the diff