Current differential replay apparatus

摘要

A current differential relay apparatus includes a ratio-differential-characteristic determining unit determining an operation in a ratio differential characteristic based on an operation level Id and a suppression level Ir, a first-current-range determining unit determining that it is activated when Id>a1Ir+b1 is satisfied, a second-current-range determining unit determining that it is activated when Id>a2Ir+b2 is satisfied with relationships a1≦a2 and b1≧b2 being satisfied where a1, a2, b1 and b2 are real numbers, and an AND operator, a reset unit, and a flip flop which determine that it is an operation in a ratio differential characteristic when both first and second current ranges are activated, and which continue the operation until an operation in the first range is reset.

主权项

1. A current differential relay apparatus comprising:
an operation-level calculating unit that calculates an operation level Id which is a vector sum of a local-terminal current and a received opposing-terminal current; a suppression-level calculating unit that calculates a suppression level Ir which is a scalar sum of the local-terminal current and the opposing-terminal current; and a ratio-differential-characteristic determining unit that determines an operation in a ratio differential characteristic based on the operation level Id and the suppression level Ir, wherein with relationships a1≦a2 and b1≧b2 being satisfied where a1, a2, b1 and b2 are real numbers, the current differential relay apparatus further comprises: a first range determining unit which determines that a first range is activated when Id >a1Ir +b1 is satisfied; a second range determining unit which determines that a second range is activated when Id >a2Ir+b2 is satisfied; and operation determining means for determining that an operation is made in the ratio differential characteristic when both the first range and second range are activated and for continuing the operation until an operation in the first range is reset.