Wind power plant sending-out line protection method considering current variation similarity

The invention belongs to the technical field of power system relay protection, and provides a wind power plant sending-out line protection method considering current variation similarity, which comprises the following steps: respectively installing relay protection devices at the two ends of a large-scale offshore wind power plant alternating current sending-out line, and collecting the instantaneous value of each phase of current at the two ends of the line; determining a fault moment, and judging whether protection is started or not according to a phase current abrupt change detection method; when the starting condition is met, subtracting the current instantaneous value of the previous cycle from the collected current instantaneous value of the previous cycle after the fault to obtain the current variable quantity of the two sides of the line, and transmitting the obtained current variable quantity to the opposite side of the line; according to the fault time, calculating the similarity of the current vari