A method for protecting busbars using a transformer-busbar circuit with lines connected via two switches

Abstract

The invention relates to electrical engineering, specifically relay protection, and can be used as a method for protecting the buses of a transformer-busbar circuit with lines connected through two switches. The technical result of the invention is the ability to prevent the disconnection of all connections connected to both buses and maintain operation of most of them during a short circuit on the buses due to superimposed faults in any switch and its switch failure backup device. This is achieved by continuously measuring the voltage at the output of the measuring and output elements of the protection device kit of each of the two buses, at the output of the relay of the “On” position of all switches and at the output of the failure protection devices of all switches connected to each of the buses, comparing these voltages with the specified standards, and if the voltages at the outputs of the measuring and output elements of some protection kit, for example the first bus, are equal to or greater than the set values ​​of the first and second standards, respectively, and the voltage UB1 at the output of the switch position relay "On", for example, for a failed switch of the j-th line, where j=1,2, …m, connected to this bus, is greater than the set third standard UЭТ3, and at the output of its switch failure backup device is less than the set voltage of the fourth standard, then after a time delay t1 = tо.в1 + △t1, where tО.В1 is the trip time of the failed switch of the j-th line, △t1 – reserve time, the first signal is generated to trip the failed switch of the j-th line and sent to the trip coil of this switch, then after time t2 = t1+ tо.в1 +△t1, if the voltage UB1>UЭТ3, the second signal is generated to trip the undamaged switch of the j-th line connected to the second bus, and if the j-th line on the opposite side is connected to a substation connected to the energy source, then, simultaneously with the second signal, a third signal is sent to turn off the switches on the opposite side of the j-th line.