METHOD OF DETERMINING POINT AND DISTANCE TO SINGLE-PHASE GROUND FAULT IN 6-35 kV ELECTRIC NETWORKS WITH ISOLATED OR COMPENSATED NEUTRAL POINT Russian patent published in 2019 - IPC G01R31/08 

FIELD: electrical engineering.

SUBSTANCE: invention relates to methods of locating damages in 6–35 kV electric networks with isolated or compensated neutral. Essence: relay protection device is installed with possibility of detecting phase currents of each connection and backup cell of distribution device, as well as with possibility of fixation of single-phase short circuits to ground in each connection of distribution device, determination of location and calculation of distance to place of single-phase ground fault. Ballast resistance is connected to reserve cell of distribution device bus section, in which there is a ground fault. High-voltage breaker of the backup cell is switched on, providing short-circuit current of short-circuited current flowing through the ballast resistance of the limited by value and time. Mutual reactive resistances of the damaged connection are taken into account when calculating the distance to single-phase ground fault according to the expression l_{1 =} {x_b⋅I_b/I₁}/{x_l + x_m⋅(I₂ + I₃)/I₁}, where x_b - value of reactive component of ballast resistance on alternating current of industrial frequency; I_b - fixed value of limited two-phase short-circuit current flowing through ballast resistance; I₁ - fixed value of two-phase fault current of faulty phase of line; I₂ and I₃ - fixed currents of undamaged connection phases with single-phase ground fault; x_m Is specific resistance of mutual induction of damaged phases.

EFFECT: technical result is fast and accurate determination of distance to single-phase ground fault location.

1 cl, 1 dwg