SU1173476A1 - Device for current protection against interphase short circuit of parallel lines aith undirectional supply (its versions) - Google Patents

Abstract

1. Device for current protection against phase-to-phase short-circuit of parallel lines with one-sided power supply, containing sets of single-stage current directional protection, connected at the receiving end of each line, and at the power end of each line, series-connected current sensor, current relay, time relay and actuator, as well as the logical element I, the first input of which is connected to the output of the current relay of its line, and the second through the logical element NOT to the output of the current relay of the parallel line, which differs from o in order to improve speed, a switch and overlay position relay are inserted at the power end of each line and connected between the output of the logic element AND and the input of the actuator, and the switch position relay is connected between the information output of the executive body of the parallel line and the third input of the logic element AND its own line . 2. Device for current protection against phase-to-phase short-circuit of parallel lines with one-sided power supply, containing sets of single-stage current directional protection, connected at the receiving end of each line, and at the power supply of each line sequentially connected current sensor, current relay, time relay and test unit , and also logs (LI elements, AND, NOT, MEMORY, the first input of the AND logic element is connected to the output of the current relay of its line, the second and third inputs, respectively, to the outputs of the logic NOT and the MEMORY of the parallel line, the output is to the executive body of its line, while the inputs Sdd 4 logic elements NOT and MEMORY are combined and connected to the output of the relay of the parallel line, different from that in order to improve speed, at the power end each line has an additional current relay and a switch position relay connected between the output of the executive body of the parallel line and the fourth input of the logic element AND its own line, with the additional current relay connected between the output current sensor and the input of the executive body of its line.

Description

The invention relates to electrical engineering and is intended for protection of parallel cable and overhead lines with a voltage of 3-110 to parallel operating blocks of a single-sided transformer. The purpose of the invention is to increase the speed of interaction. FIG. 1 shows a functional diagram of the device according to the first embodiment; see 2 the same, according to the second option. Only a part of the elements is shown; it is necessary to repair the damage on one of the lines. To disable damage on the other line, similar elements are used. Depending on the nature of the lines to be protected, the first or second version of the device is used. When protecting simultaneously operating reacted cable lines, transformer line units, transformers and overhead lines for which selective cut-off is possible, and during a short circuit in one of the lines, a cutoff current of the other line is 1.5 times greater than the maximum current setting the protection uses the second variant of the device (Fig. 2); in all other cases, the first (Fig. 1). According to the first embodiment (Fig., The device contains at the receiving end, the current relay 1, powered by current sensor 2 and power direction relay 3, powered by current sensor 2 and voltage sensor 4. The device acts on the circuit breaker disconnection. These elements are included 5 directional current, protection. At the power end, the device consists of a current relay 6, powered by a current sensor 7, a time relay 8, an actuator 9, an AND gate 10, a lining 11, a NO logic element 12, a parallel current relay 13 and a relay 14 put neither a parallel line switch, time relay 15. During a phase-to-phase short-circuit near the power source (to the start of the line), a relay 6 current of the damaged line is activated, the relay 13 of an intact line current does not work, the logic element 12 is NOT an intact line, the purpose of which is to confirm that an inrush current does not flow through the intact line and the 14 position switch of the intact line, the purpose of which is to confirm that the second line (intact) is in operation and to prevent unselective action tvie protection when working single line. Selective disconnection of the damaged line without time lag occurs through the overlay 11 from the logic element 10 I, which is triggered provided that the damaged line current relay 6 is in the actuated state, the logical element 12 is NOT and the switch position relay 14. After the damaged line is disconnected from the supply end, the current to the damage site flows through the intact line, however, the intact line is not disconnected because the control relay for the position of the damaged line is in an unresponsive state. At the receiving end, in addition to the relay 1 of the current, the relay 3 directs the power of only the damaged line, which ensures the selective disconnection of the damaged line from the receiving end without time delay (in cascade). In case of a phase-to-phase short circuit on one of the lines at a sufficient distance from the power source, relays 1, 6, 13 of both lines are activated, both from the receiving end and from the supply end. At the receiving end, in addition to the relay 1 of the current, a relay 3 of the direction of the power of only the damaged line is triggered5, which ensures the selective disconnection of the damaged line from the receiving end without time lag. After disconnecting the damaged line from the receiving end at the supply end, the relay 6 of the damaged line is in the actuated state, the logical element 12 NOT, indicating that the relay 13 of the current of the intact line has returned to its original state, and the switch position relay 14, indicating enabled state of the intact line. Selective disconnection of the damaged line without time delay (in cascade) occurs through the overlay 11 from the logic element 10 I, which is triggered provided that the damaged line current relay 6 is in the activated state, the logical element 12 is NOT and the switch position relay 14. In case of an internal phase short circuit, outside the zone, for example, at the interconnection connected to the receiving substation busbars, the protective end of the parallel lines does not work, because the power direction relays do not operate. From the side of the power supply, the relay 6 of the current I and relay 13 of both lines is in the actuated state, and the logic element 10 AND does not work. The timing of the relays 8 and 15 starts to count down and, if the damage at the receiving substation is not repaired, both lines are disconnected from the relays 8 and 15 of time. In the second variant (Fig. 2), the device comprises, at its receiving end, a current relay 16, powered by a current sensor 17, and a power direction relay 18, powered by a current sensor 17 and a voltage sensor 19. These elements are included in the kit 20 directional current protection. At the supply end, the device consists of two sets of current relays 21 and 22, powered by a current sensor.23, a time relay 24, a logic element 25 And the executive body 26, two sets of a relay 27 and 28 of a parallel current line, powered by a current sensor 29 the parallel line, the time relay 30 of the logic element 31 NOT, the logic element 32 MEMORY and the relay 33 of the switch position., the control element 34 of the parallel line. In case of a phase-to-phase short circuit at the beginning, the line (near the power supply) on the damaged line is subjected to both sets of current relay 21 and 22, and on the parallel line both sets of current relay 27 and 28 do not work. The damaged line is disconnected from the supply end without time delay from relay 21. After disconnecting the damaged line from the supply end, the current to the damage site flows through the undamaged line, but the disconnection of the intact line does not occur, because the switch of the damaged line position switch is in an unworked state. After the disconnection of the damaged line from the supply end to the receiving end, in addition to the relay 16, the relay 18 directs the power of the damaged line only. 64, which provides for the selective disconnection of the damaged line from the receiving end without time lag (in cascade). In case of a phase-to-phase short circuit at the end of the line (beyond the zone of the current cutoff relay), the current relay 22 and 28 of both lines are activated on the supply side and the logic element 32 MEMORY, the purpose of which is to memorize the operation of the current relay 28. Duration of memorization 0.51, 0 s. At the receiving end, in addition to the current relay 16, the relay 18 directs the power only to the damaged line, which ensures the selective disconnection of the damaged line from the receiving end without time lag. After disconnecting the damaged line from the receiving end at the supply end, the relay 22 of the damaged line is in the actuated state, the logic element 31 is NOT intact, the logical element 32 PA1-1DL of the intact line indicates that the relay 28 of the intact line previously operated (this prevents the non-selective protection action when there is only one line in operation) and the switch position control relay 33. Selective disconnection of a damaged line without a time delay (in cascade) comes from logic element 25 I, which is triggered on condition that relay 22 of the damaged line current, logic elements 31 NOT, 32 MEMORY and relay 33 are in the actuated state. the position of the switch intact line. In case of a short circuit on the tires of the receiving substation or the lines running from the buses of this substation, the fast-acting protection does not work because they do not activate the directed protection at the receiving ends of the lines. Both current and current relays 22 and 28 are actuated and, if the damage at the receiving substation is not repaired, both lines are disconnected from relay 24 and 30 of the belt. Thus, the proposed device provides for selective disconnection of the damaged line without time spilling during a short circuit of the line and disconnecting both lines with a high time at short circuit on the receiving substation tires.

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Claims (2)

1. A device for current protection against interphase short circuit of parallel lines with one-way power supply, containing sets of one-stage current directional protection included at the receiving end of each line and at the supply end of each line in series with a current sensor, current relay, time relay and actuator, as well as a logical element AND, the first input of which is connected to the output of the current relay of its line, and the second, through the logic element, is NOT to the output of the parallel current relay, characterized in that; in order to improve performance, a switch position relay and an overlay connected between the output of the logical element And and the input of the executive body are introduced at the supply end of each line, and the relay of the position of the switch is connected between the information output of the executive body of the parallel line and the third input of the logical element And of its line. 2. A device for current protection against interphase short circuit of parallel lines with one-way power supply, containing sets of one-stage current directional protection included on the receiving end of each line and on the supply end of each line in series _with a current sensor, current relay, and relay 1S change the test organ, as well as the AND, NOT, MEMORY logic elements, the first input of the AND logic element being connected to the output of the current relay of its line, the second and third inputs, respectively, to the outputs of the logic elements in NOT and MEMORY of the parallel line, the output is to the executive body of its line, while the inputs of the logic elements NOT and MEMORY are combined and connected to the output of the parallel line current relay, characterized in that, in order to improve performance, an additional input is introduced at the supply end of each line a current relay and a switch position relay connected between the output of the parallel line actuator and the fourth input of the logical element AND of its line, with an additional current relay connected between the output of the current sensor and the input executive body of his line.