RU2017301C1 - Device for distance protection of network - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: device includes swinging interlocking 13, resistance relay unit 1 incorporating intermediate voltage and current transformers 2, 3, 4, 5, 6, 7, measurement elements 8, 9, 10 of phase resistance, first OR gate 11, AND gate 17 with three inputs which first input is connected to output of resistance relay unit 1, which second input is linked to output of swinging interlocking 13 and to first input of unit 16 of detection of operation priority which output is coupled to third of AND gate. In case of fault operation of measurement element 12 of voltage of reverse sequence is ensured. Swinging interlocking in this case does not operate. Signal from second OR gate 14 comes with time delay of element 15 to input of unit 16 of detection of operation priority. With this zero signal is established across output of the latter which goes to input of AND gate 17 and interlocks protection. EFFECT: increased reliability and efficiency of distance protection. 1 dwg

Description

 The invention relates to electrical engineering, namely to remote protection of power system facilities.

 A device is known for remote protection of a network, comprising a block of a resistance relay (BRS) of a protection stage, blocking during swings (BK) and blocking during a malfunction in voltage circuits (BNN), the inputs of which are intended to be connected to a protected network, an AND element with three inputs, the first whose input is connected to the output of the BRS, the second input to the output of the BC, the third input to the output of the BNN, and its output is the output of the protection level [1].

 The disadvantage of this device is that there is the possibility of distance protection failure due to its false blocking from BNN in the conditions of a short circuit to ground or the presence of pickup in the connecting wires of a voltage measuring transformer in the event of a short circuit with high currents in the protection zone. This limits the reliability of distance protection.

 The closest in technical essence to the claimed device is a device for remote network protection, containing BK, BNN, BRS, including intermediate voltage transformers, intermediate current transformers, measuring phase resistance and the first OR element, the inputs of which are designed to connect to the protected network, element And with three inputs, the first input of which is connected to the output of the BRS, the second input - to the output of the BC and to the first input of the priority detection unit based on the trigger-arbiter , The third input - to the output unit identifying priority response, and BNN output from time delay element for triggering is connected to the second input of the detection block priority switching [2]. This device eliminates failures of distance protection in the context of a short circuit to ground or the presence of pickups in the connecting wires of a voltage measuring transformer when a short circuit occurs in the protection zone, which increases the reliability of protection.

 However, it cannot detect malfunctions in the circuits of the intermediate voltage transformers of the BRS. The indicated can lead to a false positive response, for example, with external short circuit. In addition, this device has an intermediate voltage transformer in the BNN, the inputs of which are designed to connect a voltage measuring transformer in the "star" and "open triangle" circuits, which increases the dimensions of the device and the consumption from the input voltage circuits.

 The proposed device does not have an intermediate voltage transformer in the BNN, which reduces the dimensions of the device and the consumption of the input voltage circuits. The essence of the proposal lies in the fact that a negative sequence voltage measuring element and a second OR element are introduced, which are connected to the device elements so that it becomes possible to control faults not only in the voltage measuring transformer circuits, but also in the intermediate voltage transformer circuits in the BRS. The aforementioned increases the reliability of the failure of protection in case of faults in the circuits of intermediate voltage transformers in the BRS.

 The drawing shows a functional diagram of a device for remote protection of the network, where 1 - BRS, including, for example, three intermediate transformers 2, 4, 6 voltage, three intermediate transformers 3, 5, 7 current, three measuring body 8, 9, 10 resistance, for example, the second stage of phases and the first OR element 11 with three inputs, 12 is the measuring element of the negative sequence voltage, 13 is the BC, 14 is the second OR element with two inputs, 15 is the response time delay element, 16 is the priority detection unit for trigger basis Bitra, 17 - element and three entrances.

 The device contains BK 13 and BRS 1, including intermediate voltage transformers 2, 4, 6, intermediate current transformers 3, 5, 7, measuring elements 8, 9, 10 of the phase resistance and the first element OR 11, the inputs of which are designed to connect to the protected network , element And 17 with three inputs, the first input of which is connected to the output of the first element OR 11 in the BRS 1, the second input to the output of the BC 13 and to the first input of the block 16 based on the trigger-arbiter, the third input to the output of the block 16. The output of the element 15 time delay for operation connected to the second input unit 16, the inputs of the measuring body 12 of the negative sequence voltage are connected to the outputs of the intermediate transformers 2 and 4 voltage. The inputs of the second OR element 14 are connected to the output of the measuring element 12 of the negative sequence voltage and to the output of the BRS 1, and the output of the second OR element 14 is connected to the input of the response time element 15.

 The device operates as follows.

 In the normal mode of the power system, blocks 1.12-17 are in the initial state, and there are no working signals at their outputs.

 When a short circuit occurs in the operating zone, the BRS 1 is triggered, and a working signal appears at its output, which is fed to the first input of element And 17. Since BC 13 is also triggered, the working signal that arose at its output goes to the second input of the element And 17 and the first input of block 16. Block 16 is made on the basis of a trigger-arbiter, consisting of two elements of the K56ILA7 chip, covered by feedback. At the same time, the high-level working signal "1" from KB 13 arrives at the first input of the trigger arbiter in block 16 earlier than the high-level signal "1" from blocks 12, 14, and 15, which arrives at the second input of the trigger arbiter in block 16. This is due to the fact that there is a delay of element 15 for a given time (for example, 0.02 s), sufficient for the total response time of blocks 12, 14 and 15 to be longer than the response time of BC 13. Moreover, at the output of the first trigger element, the arbiter sets the signal "0", which comes in feedback from the output of the first ele cient to the second element in the trigger-input arbiter. Therefore, the signal “1” is stored at the output of the trigger-arbiter even after the element 15 is triggered. The signal “1” of the output of the trigger-arbitrator is sent to the third input of the element And 17. Moreover, at the first output of the device (i.e., at the output of the element And 17) , which is the output of the protection stage, a working signal appears, which ensures the disconnection of the protected network section. After shutdown, blocks 1, 12-17 return to their original state. Since BC 13 provides the start of protection for a given time, which is longer than the duration of the protection, the false alarm output 2 is excluded.

 In the event of a malfunction in the voltage circuits (for example, if at least one of the voltage phases is interrupted), the response of the measuring element 12 of the reverse sequence voltage and the possible response of the BRS 1 are ensured. However, BC 13 does not work. In this case, through the OR element 14 with the time delay of the element 15, the signal "1" is supplied to the second input of the arbiter trigger in block 16. At the same time, the signal "0" is set at the output of the trigger arbitrator, which goes to the third input of the And 17 element and blocks the protection . At the same time, feedback from the output of the second element to the input of the first element in the arbiter trigger receives a signal "0", which prohibits the operation of block 16 even after the possible subsequent operation of BC 13 (for example, due to the appearance of an external fault) when the operation of the AND element 17 is still prohibited. The signal "0" from the output 2 of the device is supplied (for example, through an additional inverter and an element of the time of the functional protection control) to the alarm circuit in the voltage and protection circuits. The same signal is provided in the event of a breakdown of all three voltage phases, when the organ 12 does not work, however, blocks 8-11, 14, 15 are triggered, as well as in the case of excessive operation of at least one of the blocks 8, 9 or 10, due to malfunctions in them or because of the appearance of a malfunction in blocks 2, 4, or 6. After eliminating the malfunction, blocks 8-12 return to their original state. Therefore, the block 16 also returns to its original state.

 Thus, in comparison with known devices, the proposed one expands the completeness of protection monitoring by additionally monitoring the health of voltage sensors and resistance measuring organs. At the same time, quickly enough, for example, after 0.02 s, false protection operation is excluded. In addition, the proposed device does not have an intermediate voltage transformer, which reduces the dimensions of the device and the consumption of input voltage circuits.

 Technical and economic efficiency of the device is formed by increasing the reliability of power supply.

Claims (1)

 DEVICE FOR REMOTE PROTECTION OF THE NETWORK, containing a blocking during swings and a block of resistance relays, including intermediate current transformers and intermediate voltage transformers, the inputs of which are designed to connect to the phases of the protected network, and the outputs are connected to the measuring organs of phase resistance, the outputs of which are connected to the inputs of the first element OR, the output of which is the output of the resistance relay block, the AND element with three inputs, the first input of which is connected to the output of the resistance relay block, the second the input is to the blocking output during swings, and the output of the AND element is a protection output, characterized in that an inverse voltage measuring element is additionally introduced into it, the inputs of which are connected to the outputs of the intermediate voltage transformers, the inputs of the introduced second element OR are connected to the output of the voltage measuring organ in the reverse sequence and to the output of the resistance relay block, the output of the second element OR through the newly introduced delay time element for operation is connected to the first th entry unit identifying priority response, output when swing lock is connected to the second input of the detection trigger priority, the output of which is designed for signaling a fault in the voltage protection circuits and, and connected to the third input element I.