FIELD: electrical engineering.
SUBSTANCE: used for relay protection of cable lines with a voltage of 6-35 kV, operating with an insulated or resistively grounded neutral during single-phase ground faults. Zero-sequence current sensors measure the values of zero-sequence currents arising in the protected line during single-phase ground faults. The measured values are supplied to the first input of the relay element of the protection unit with a specified response setting. The relay element compares the zero-sequence current of the line with the current set point for protection against single-phase ground faults. Based on the input signals, the first microcontroller determines the primary parameters of the cable line and the phase speed of pulse propagation along the line, based on which the reflectometer determines the distance on the line to the location of the fault. The second microcontroller calculates the resistance value of the line short circuit and adjusts the set current according to this value. If the value of the adjusted setting current is less than the zero-sequence current in the protected line, then the relay element will operate and disconnect this line from the bus section.
EFFECT: implementation of intelligent current protection against single-phase ground faults on cable lines in networks with an isolated and resistively grounded neutral.
1 cl, 1 dwg
