REMOTE METHOD FOR PROTECTION AND AUTOMATIC CONTROL OF ELECTRIC POWER TRANSMISSION LINE Russian patent published in 1996 - IPC

FIELD: devices for remote protection and search of faults. SUBSTANCE: method involves measuring voltage and current of phase and zero line, separating ground and inter-phase short circuits, selecting specific phase, detecting of reactive characteristics of possible short circuits. Among latter characteristics first one corresponds to assumption that fault is at beginning of line, second one - in other point, for example, at end of line. Direct direction current in specific phase is set equal to reverse direction current for single phase short circuit, or to inverse value of reverse direction current for double phase short circuit, or to inverse value to sum of reverse direction current and zero line for double phase short circuit to ground. Remote protection starts in plane of first and second reactive characteristics. Sort circuit position is detected as point, which is closest to beginning of line where reactive characteristic is zero. Value of reactive characteristic equals multiplication of reactive power and reactive resistance and it sign equals to sign of reactive power. EFFECT: increased functional capabilities. 18 dwg, 1 tbl