RU50476U1 - NON-SELECTIVE PROTECTION OF FEEDERS OF A CONTACT CONTACT NETWORK FROM SHORT-CIRCUIT CURRENTS THROUGH GREAT TRANSITION RESISTANCE - Google Patents

Abstract

Non-selective protection of the feeders of the contact AC network against short-circuit currents through a large transition resistance The device relates to the protection of electric networks from short-circuit currents, in particular, to the protection of the feeders of the contact network of the electric railway AC. The purpose of the proposed device is to increase the sensitivity to short-circuit currents through a large transition resistance with non-selective protection of the inter-substation zone. A device for the non-selective protection of the feeders of the contact AC network from short-circuit currents through a large transition resistance, comprising a current sensor and a voltage sensor of the feeder of the contact network, a braking unit for higher harmonics of the feeder current, an AND logic element, a remote element with a quadrangular angular response characteristic extended along axis of active resistances.

Description

The device relates to the protection of electrical networks from short circuit currents, in particular, to the protection of the feeders of the contact network of electric railways of alternating current.

A device for protecting against short-circuit currents through a large transition resistance, consisting of a remote element with a quadrangular response characteristic extended along the axis of active resistances, and a braking unit for the remote element with higher harmonic components contained in the current of the protected feeder [1]. The specified device is a prototype of this.

The device reliably identifies faults through a large transition resistance in the zone from the traction substation to the sectioning station with a nodal power supply circuit with selective

protection of the inter-substation zone. However, in case of non-selective protection, when there is no relay protection on the feeders of the sectioning post, when the protection of the feeder of the traction substation directly supplying the circuit is triggered, an increase in the charging currents by the feeder of the adjacent path and the feeders of the adjacent substation is not enough to trigger their sets, which is a failure [2] .

The purpose of the proposed device is to increase the sensitivity to short-circuit currents through a large transition resistance with non-selective protection of the inter-substation zone.

The device is shown in the figure.

This goal is achieved by the fact that in the device for protecting the feeders of the contact AC network from short circuit currents through a large transition resistance, containing the current sensor DT and the voltage sensor DN of the feeder of the contact network, the braking unit for the higher harmonics of the current of the feeder BT, the logic element And, remote DE element with a quadrangular angular response characteristic extended along the axis of active resistances, one input of which is connected to the output of the voltage sensor, and the other input is connected to the output of the sensor Single current braking block entrance of higher harmonics is connected to the output of the current sensor of the feeder, and an output connected to an input of the AND gate, the other input of which is connected to the output of the spacer member, the two introduced additional signal repeater

P1 and P2, the inputs of which are connected to the output of the logical element And, moreover, at the output of one repeater a signal is generated to turn off the circuit breaker of the protected feeder, and at the output of another repeater a signal is generated to turn off the circuit breaker of the feeder of the adjacent path.

From current sensors DT and voltage DN information about the current and voltage on the feeder of the contact network in accordance with the figure enters the inputs of the blocks DE and BT. In the normal load mode, the content of higher harmonics in the feeder current is significant, therefore, there will be a ban on the BT output, and even if the load resistance vector gets into the DE operation region and an enable signal is formed at its output, at the output of the And element, and, therefore, at the outputs Repeaters of signals P1 and P2 do not form trip signals. In the case of a metal short circuit on the line, the content of higher harmonics in the feeder current will significantly decrease and there will be an enable signal at the output of the BT. However, due to the predominance of the inductive component circuit in this type of circuit, the feeder resistance vector will be higher than the DE operation area, the output of which will be prohibited, and the protection will not respond. When shorted through a significant transition resistance, the content of harmonics in the feeder current will be slightly higher than their content in the metal short circuit mode and lower than in the normal operating mode, which will lead to the formation of an enable signal at the input of the And element from the BT unit. The second enable signal will be

formed by the DE block when the resistance vector enters the response region. The generated control signal from the And element through repeaters P1 and P2 simultaneously enters the circuit of the high voltage circuit breakers of the damaged feeder and adjacent feeder of the adjacent path, respectively. After the circuit breakers are turned off, the circuit will only be energized from an adjacent substation. The changed current distribution will lead to a significant increase in emergency currents flowing through its feeders, which will trigger the corresponding protection sets.

LIST OF USED SOURCES

1. Pat. RU 40544 U 1 Russia, 7 Н 02 Н 3/00, В 60 М 1/00. Protection of feeders of a contact AC network from short circuit currents through a large transition resistance / G.S. Magay, I.A. Kremlev (Russia). - 2004113537/22; Announced on 05/05/2004; Publ. 09/10/2004. Bull. Number 25.

2. Figurnov EP Relay protection. - M .: Zheldorizdat, 2002. 720 p.

Claims (1)

A device for the non-selective protection of the feeders of the contact AC network from short-circuit currents through a large transition resistance, comprising a current sensor and a voltage sensor of the feeder of the contact network, a braking unit for higher harmonics of the feeder current, an AND logic element, a remote element with a quadrangular angular response characteristic extended along axis of active resistances, one input of which is connected to the output of the voltage sensor, and the other input is connected to the output of the current sensor, the input of the braking unit higher harmonics is connected to the output of the feeder current sensor, and the output is connected to the input of the logical element AND, the other input of which is connected to the output of the remote element, characterized in that it additionally includes two signal followers, the inputs of which are connected to the output of the logical element And, and the output of one repeater generates a signal to turn off the circuit breaker of the protected feeder, and the output of another repeater forms a signal to shut off the circuit breaker of an adjacent feeder of the adjacent path.