Patent ID: 11973340

Abstract:
A line current iM(k0) of an M side of a first direct-current transmission line is collected at a moment k0. A line current iM(k0−ts) thereof is collected at k0−ts. At a moment k0, a differential value diM(k0) of a current of the side of the first direct-current transmission line is calculated according to the line current iM(k0) and the line current iM(k0−ts). It is determined whether the differential value diM(k0) of the current meets a protection enabling criteria. If so, direct-current protection for the M side of the first direct-current transmission line is enabled. A line current iM(j) of the M side of the first direct-current transmission line is collected at a moment j. A line current iM(j−ts) thereof is collected at a moment j−ts. A differential value diM(j) of the current of the M side of the first direct-current transmission line at the moment j is calculated according to the line current iM(j) and the line current iM(j−ts).