ZERO-SEQUENCE RESISTIVE CURRENT DIFFERENTIAL PROTECTION METHOD FOR INTER-STATION TIE LINE OF SMALL-RESISTANCE GROUNDING SYSTEM

Disclosed is a zero-sequence resistive-current differential protection method for an inter-station tie line of a low-resistance grounding system, including the following steps: 1) acquiring three-phase currents I□A1, I□B1 and I□C1 of a three-phase current transformer at a sending end of the tie line, and a zero-sequence voltage U□01 of a bus of a power station at the sending end of the tie line, and acquiring three-phase currents I□A2,I□B2 and I□C2 of a three-phase current transformer at a receiving end of the tie line, and a zero-sequence voltage U□02 of a bus of a power station at the receiving end of the tie line; 2) calculating a resistive zero-sequence current I□01r at the sending end of the tie line according to I□A1,I□B1,I□C1 and U□01; 3) calculating a resistive zero-sequence current I□02r at the receiving end of the tie line according to I□A2,I□B2,I□C2 and U□02; 4) calculating a zero-sequence resistive differential current I□0dr and a braking current I□0s according to I□01r and I□02r; and 5) performing a zero-sequence differential protection action when I□0dr>I□0qd or I□0d>KI□0s.