SU1713010A1 - Method of power supply recovery under emergency conditions in insulated-neutral networks - Google Patents

Abstract

The invention relates to power engineering and can be used in distribution networks x 6-35 kV with insulated neutral. The goal is to increase reliability. To restore the power supply in the double-ground-to-ground mode on lines connected to the first busbar section, there is a ground to the second busbar section; if there is no short circuit, one of the damaged lines is connected to the second busbar section, if there is a shortcut. damaged phases are detected on both sections of the tires and the line, the damaged phase of which coincides with the damaged phase of the second section, is connected to the second section. 6 yl.

Description

The invention relates to electric power industry and can be used to restore power supply with double ground faults in distribution networks of 6-35 kV, operating with an insulated neutral.

The aim of the invention is to improve the reliability of power supply during emergency conditions in a network with insulated neutral.

Figure 1 is an electrical network diagram; figure 2 - functional diagram of the device for implementing the method; FIG. 3 is a diagram of a dual lock control unit on the ground (BKDZ); figure 4 is a diagram of the body control ground fault (OKZ); Fig. 5 is a diagram of a phase mismatch control unit (BKNF); 6 is a diagram of a phase coincidence control unit (B CSF).

Power transformers 1.2 (Fig. 1), operating with an insulated neutral, are connected to the corresponding sections of buses 3.4, between which the switching device 5 is installed. To the section of tires 3 through the switching device 6 a three-phase transmission line 1 is connected, through the switching device 8 bus bypass section 9, ground fault monitoring unit 10. Bus section 4 through switching devices 11, 12 are connected to power transmission lines 13, 14, through switching device 15 - bus bypass section 16, ground fault monitoring unit 17. Between bypass The bus sections 9, 16 are equipped with a switching device 18. The bypass sections of the buses 9, 16 are connected through switching devices 19. 20, 21 are connected, respectively, to power lines 7, 13, 14. The ground fault monitoring unit 10 and 17 can be used NTMI series voltage transformers installed in substations with relay connected for phase voltages.

A device for implementing the method (FIG. 2) contains a double-closure control unit (BKDZ) 22 and an earth-fault control (OC) unit 23, the outputs of which are connected to a phase mismatch control unit (BKNF) 24, the output of which is connected to the inhibitory input of the first element BANGE 25. The permissive input of the BANCH element is connected to the BKDZ 22 output, the output of the first BAN 25 element is connected to the phase coincidence control unit (BXF) 26 and through the JUMP device element

27 with the permissive input of the second element BANGE 28, the output of the BCSF 26 is connected to the first executive body 29 and the prohibiting entrance of the second element BAN 28, the output of the second element BAN

28 is connected to the second executive body 30, the output of the OKZ 23 is connected to the control inputs of the BCSF 26. The control inputs of the BKDZ 22 are connected to relay protection against phase-to-phase short circuits of the lines 7, 13, 14. The control inputs of the OKZ 23 are connected to the earth fault monitoring units 10 and 17. The control inputs of the BCSF 26 are connected to the auxiliary contacts of the disconnected position of the switching devices 6. 11, 12. The number of the outgoing lines can be arbitrary, in this case only the contacts of the relay protection against phase-to-phase short circuits and blinds are added. Contacts to the OFF position switching devices.

The control unit of the double ground fault 22 (FIG. 3) is made in the form of series-connected contacts 31, 32, 33 of relay protection against phase-to-phase short-circuits of lines 7, 13, 14, respectively. Contact groups 31-32, 3133, 32-33 are interconnected in parallel VI are connected to an intermediate relay 34, contacts 35 of an intermediate relay are connected in parallel to the specified contact groups.

The ground fault monitoring control unit 23 (FIG. 4) contains two ground fault control units 10, 17 and six intermediate relays 36-41, the first three of which 36, 37, 38 are connected via contacts 42,43,44 of the undervoltage relay 45, 46, 47 ground fault closure control units 10,

Intermediate relays 39, 40, 41 are connected via contacts 48, 49, 50 of the undervoltage relay, respectively, 51, 52, 53 of the earth-fault control unit 17.

Phase mismatch control unit

BKNF 24 (FIG. 5) is made in the form of parallel-connected contacts 5455, 56-57, 58-59 of the same name, respectively, intermediate relays 360 41, these contact groups are interconnected in series and connected to the second contacts 60 of the intermediate relay 34 of BKDZ 22.

Phase Matching Control Unit 26 BCSF

5 is made in the form (6) of the pairwise-serially connected contacts 61-62, 63-64, 65-66, of the same-named phases of the intermediate relays 36-41 of the ground-fault control unit 23. These contact groups are interconnected in parallel and connected to parallel-connected block contacts 67, 68, 69 switching-off switching devices waste u. 7, 13, 14. Contacts 61-66 are made with a delay for actuation.

The implementation of the method is as follows.

With a ground fault, for example, on phase A of line 14 and later on a short circuit on phase B of line 13, the air lines fed from the bus system 4 operate in double ground to one of the lines, for example 14 {with time is shorter), switched off by the switching device 12.

According to the proposed method, it is necessary to check the absence of a ground fault (using the ground fault control unit 10) on another section of tires 3. In the case of

0 absence of a ground fault on the busbar section switches on the switching devices 21, 18 and 8, At this line, 14 receives power from the bus section 3. Since sections 3, 4 are connected to separately working

5 transformers with insulated neutral on the low-voltage side, the dual-ground-to-earth mode switches to ground-to-ground mode on both sections of buses 3 and 4, but at the same time

0 consumers on line 14 receive power.

If there is a ground fault on the busbar section 3, it is necessary to check on which phase the short to ground. Let's say.

5 that the earth fault on line 7 on phase A, while the order of action remains the same. The disconnected line 14 (since its phase A is damaged) is connected to the bus section 3. For this, the switching devices 21, 18, 8 are turned on.

If on line 7 there is a ground fault at az B, it is necessary to disconnect line 13 from the busbar 4 section using the switching device 11 and transfer it to the busbar 3 power supply. For this, the switching devices 20, 18, 8 are turned on. 14 is switched on by the switching device 12. In this case, two lines 7 and 13 are fed from the busbar section 3, in which a ground fault is in the same phase of 10 V, and line 14 is powered from the busbar section 4, since it has a short circuit to z.emlyu in phase A.

In case the sections of tires 3 are short-circuited to earth at phase C, and at sections of tires 4 at phases A and B, the restoration of electrical-15 supply by the proposed method is impossible.

The device works (figure 2) as follows. When earth fault occurs, for example, on phase A of line 14. Relay 20 of minimum voltage 51 of earth fault control unit 17 is activated, its contacts 48 are closed in the power supply circuit of intermediate relay 39 (figure 4), but intermediate relay 39 does not operate, so as the control unit 25, ground fault 23 is connected to the power supply circuit in series with the BKDS 22. Since there are no double ground loops with two outgoing lines in this case, the BKDS 22 contacts do not close. In 30, further, when a short-circuit is in phase B of line 13, a minimum voltage relay 52 is activated (Fig. 4). its contacts 49 in the supply circuit of the intermediate relay 40 are closed. In case of double circuit, 35 relay protection against phase-to-phase short circuit i is activated, installed on lines 13,14 and their contacts 32, 33 are closed in BKDS 22. Receiver 34 and Relay 39, 40 in OKZ 23 receive power. 35 of the intermediate relay .34, the contacts 32, 33 are closed and by-pass. Due to this, the damaged phase is fixed after the disconnection of one of the lines. In the following, an analysis of the mismatch of phases 45 of BKNF 24 (Fig. 5) is carried out. The contacts 60 of the intermediate relay 34 are closed. Since the phases A and B are damaged and the bus sections 4 are closed, the contacts of the 55-intermediate relay 39 and contacts 57 of the intermediate relay 40 are closed. In case of 50 no closures To the ground, bus sections 3 of the minimum voltage relay 45, 46, 47 of the earth fault circuit 10 does not work, the intermediate relays 36,37,38 do not receive power and their contacts 54, 56, 55 58 do not close and the signal at the output of BKHSS 24 is zero. The signal from the BKDZ 22 output through the first BANCH element 25 is fed to the BCSF 26 and the DELAY 27 element. After turning off the line 14, the undervoltage relay 51 returns to its original state, the intermediate relay 39 loses power (Fig. 4). There is no signal at the output of BKNF 24, therefore a signal at the input of BKSF 26 and a delay element 27 is present. When disconnecting the switching apparatus 12 for; Its block contacts 68 and BCSF 26 are knocked out (FIG. 6). After line 14 is disconnected, line 13 remains in operation with a ground fault in phase B, contacts 63 (Fig. 6) of intermediate relay 40 are closed, but the signal at the output of BCSF 26 is zero, since contacts 64 of intermediate relay 37 are open (no ground fault on another section of tires 3). The first executive body 29 (figure 2) does not work, the signal at the prohibitory input of the second element BANGE 28 is. After a time determined by the DELAY 27 element, the signal through the BANGE 28 element arrives at the second executive body 30. The activation of the second executive body 30 means that the disconnected line needs to be switched to another bus section. Thus, in this case, the operating personnel do not need to conduct an analysis of the state of the electrical network. Switching can be done automatically. When the first actuator is triggered, switching devices must be switched on, transferring the disconnected line to another bus section (in this case, switching on 21.8. 18).

If there is a ground fault on the other section of the tire 3, the device operates as follows.

When a ground fault occurs, for example, at phase A of line 14, the minimum voltage relay 51 of the ground fault control unit 17 is activated. Its contacts 48 are closed in the power supply circuit of intermediate relay 39 (Fig. 4). Suppose there is a phase A ground fault on line 7. This triggers the minimum voltage relay 45 of the ground fault control unit 10. Its contacts 42 are closed in the power supply circuit of the intermediate relay 36 (Fig. 4). but intermediate relays 36, 39 do not get pi. Since they are included in the power supply circuits afterwards with the BKDS 22. Subsequently, when a short-circuit is in phase On line 13, the undervoltage relay 52 is activated, its contacts 49 in the power supply circuit of the intermediate relay 40 are closed. In case of double closure, BKDZ 22 is triggered. The intermediate relay 34 in BKZD 22 and 36, 39, 40 in OKZ 23 receives power. The contacts 54 of intermediate relay 36, 55 - intermediate relay 39, 57 - intermediate relay 40 in BKNF 24 are closed (Fig.5 ). Close contacts

60 of the intermediate relay 34. Since one of the contacts 58 or 59 of the intermediate relB is not closed, the signal at the output of BKNF 24 is zero. The signal from the BKZD 22 output through the first BANCH element enters the BKSF 26 and the delay element 27. After turning off the line 14, the undervoltage relay 51 returns to its original state, the intermediate relay 39 loses power (Fig. 4). the signal at the output BKFN 24 is missing, therefore, the signal at the input of the BKSF 26 and the delay element 27 is present. When the line 14 is disconnected, the blocking contacts 68 in BCSF 26 are closed (fig.b). After disconnecting line 14, line 13 remains in operation with a short to ground in phase B, contacts 63 (fig.b) of intermediate relay 40 are closed. Since the other section of the busbar 3 is closed phase A. then the contacts 62 of the intermediate relay 36 are also closed, but the signal at the output of BKSF is zero, since the contacts 61 of the intermediate relay 39, the contacts 64 of the intermediate relay 37 are open. The first executive body 29 (figure 2) does not work, the signal at the prohibitory input of the second element BAN 28 is zero. After a time determined by the DELAY 27 element, the signal through the BANGE element enters the second executive body 30. The second actuator 30 actuates, which means that the damaged phase of the disconnected line 14 coincides in phase with the damaged phase of the line 7, which comes from the other section of bus 3, therefore it is possible to disconnect line 14 to switch to another section of bus 3. Switching devices 21. 8, 18 are switched on.

In the case of a ground fault on line 14 of phase A, on line 13 of phase B. On line 7 of phase A, when line 13 is disconnected, the device operates in the same way until line 13 is disconnected. After line 13 is disconnected, the undervoltage relay 52 returns to its original state intermediate relay 40 loses power (FIG. 4); there is no signal to output BKNF 24. When the line 13 is disconnected, the block contacts 67 of the switching device 11 are closed. After the line 13 is switched off, the line 14c remains in operation with a ground fault in phase A. The contacts 61 of the intermediate relay 39 are closed. Since on the other section of the bus 3 phase A is closed, the contacts 62 of the intermediate relay 36 are also closed, therefore the signal at the output of the BCSF 26 is present. The first executive body 29 operates, at the same time the signal from the BKSF 26 is fed to the prohibiting entrance of the second element BANGE 28, therefore the second executive body 30 does not work. Tripping

the first executive body 29 means that the disconnected line 13 must be turned on to its section of tires 4, and the line 14 remaining in operation should be transferred to another

bus section 3. To do this, you must turn off line 14 with switching device 12, turn on switching devices 11, 21, 9, 18. According to this algorithm (disabling the line remaining in operation and transferring it to

another section of tires and switching on a disconnected line to its section of tires) it is necessary to act when the first executive unit 29 is triggered.

In case of a ground fault on line 14 of phase A, on line 13 of phase B, on line 7

phase C to restore the power supply of the proposed method is impossible, since in any combination a double circuit to earth is preserved. With such a combination of phases (in total, all three are damaged), the minimum voltage relay 51, 52 of the ground fault control unit 23 and 47 of the ground fault control unit 10 are triggered. Intermediate relays 38, 39 are activated. 40. Contacts 55 of the intermediate relay 38 close. 57 - intermediate relay 40, 58 - intermediate relay 38 and at the output of BKNF 24 there is a signal that is fed to the prohibiting input of the first element BANGE 25. Therefore, in this case it is not

The first 29 and second 30 executive bodies are activated.

The first element of BAN 25 should be held when the inhibit signal is removed. This is possible by applying

any pointing-relay with drop-down mechanism. The winding of the specified relay serves as a prohibiting input, and normally closed contacts - allowing input. In case intermediate relays

36-41 do not have contacts with time delay and no time delay, for the implementation of BKNF 24, BCSF 26 can be used instead of one intermediate relay. 36-41 two in parallel

included with the desired response characteristic of the contacts. The time delay for the operation of contacts 61-66 should be longer than the response time of switching devices. The delay time of the element 27 must be greater than the response time of the contacts 61-66. After operation of any of the executive bodies 29. The 30 BCS 22 should return to its original state by removing power from the intermediate relay 34. The necessity of introducing the AC 23 is due to the fact that the moment of switching the fault to dual ground fault mode with two outgoing lines. If the minimum voltage relay is applied directly, then a false operation of the phase coincidence control unit 26 is possible due to the fact that the ground fault mode is long and one of the contacts 61-66 or two of them (provided that. voltage) can be pre-closed, for example, when a ground fault occurs on phase A on busbar sections 3, 4 contacts 61 are closed. 62 and if one of the lines is disconnected and its blocking contacts are closed, false operation is possible. To eliminate this, a new BCSF time line 26 would be necessary. The necessity of introducing BCS 22 is explained by this. that a double circuit to earth can only be on one line, while it does not make sense to transfer it to another bus section, since the double circuit to earth on this line is preserved. Thus, the proposed method makes it possible to increase the reliability of power supply in case of double ground loops, and the proposed device makes it possible to automate the process of power supply restoration. Claims of Invention A method of restoring power supply during emergency conditions in an insulated neutral network consisting of two transformers connected respectively to two sections of busbars. operating separately, several lines of the bus bypass system departing from each section, in which, if one of the bus sections is damaged, the lines connected to this section are transferred to the second section, which is different, using the bus bypass system, so that increasing the reliability of power supply in case of double circuit to earth, on two lines extending from the first section, the presence of a circuit on the second section is checked, if there is no one, one of the circuit lines is transferred to the second section, and in the presence of a circuit the phase is determined the closures and transfer to the second section of the line, the phase of the circuit on which coincides with the phase of the circuit on the second section of tires.

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Claims (1)

Claim A method of restoring power supply during emergency conditions in an isolated neutral network consisting of two transformers connected respectively to two bus sections operating separately, several departing from each section of the bus bypass system lines, in which, if one of the bus sections is damaged, the line connected to this sections, with the help of a bypass system of tires is transferred to the second section, with the fact that, in order to increase the reliability of power supply in case of a double earth fault, on two outgoing from the first The sections of the lines check for a fault in the second section, if it is absent, one of the outgoing lines with a fault is transferred to the second section, if there is a fault, the phase of the fault is determined and the line is transferred to the second section, the fault phase of which coincides with the phase of the fault in the second bus section . forest A8C Figure 2 Figz