Optimization method for matching of branch zero-sequence protection outlet and quick switching device
By modifying the outlet method of the I section of the variable branch zero-sequence protection section of the high-voltage variable branch and the cable connecting the quick-scoring device, the automatic locking and starting of the quick-scoring device in the high-voltage factory system is achieved, solving the problem that the quick-scoring device cannot be started after the branch zero-sequence protection section II section is operated, and ensuring the stable supply of the high-voltage factory bus.
Patent Information
- Application Number
- CN202411660751.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-20
- Publication Date
- 2025-02-25
AI Technical Summary
In the high-voltage factory system, the branch zero-sequence protection section II cannot automatically start the quick-cut device after the operation, resulting in the power loss of the factory bus power supply, affecting the safe shutdown of the unit and the safe operation of the equipment.
By modifying the exit method of the zero-sequence protection section I of the high-factory variable branch is "high jump factory variable branch switch" and "locking switch", and using the cable spare core of the transmission and transformer protection cabinet to the quick-cutting device, the new outlet relay contact is connected to the spare opening of the quick-cutting device, so as to realize the automatic locking and starting of the quick-cutting device.
It solves the problem that the quick-cut device cannot be started after the branch zero-sequence protection section II operation, ensures that the high-voltage plant bus does not lose power, and improves the safe shutdown of the unit and the safe operation of the equipment.
Smart Images
Figure CN119518624A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of relay protection and safety automatic devices, and in particular to an optimization method for the coordination between a branch zero-sequence protection outlet and a quick-cut device. Background Art
[0002] At present, most of the high-voltage power plant systems in my country adopt the resistance grounding operation mode. When high-resistance grounding occurs, the plant transformer differential protection cannot be operated due to the small grounding current, so branch zero-sequence protection must be set. The single-phase grounding protection of the plant system is generally equipped with two-stage zero-sequence current protection. The zero-sequence I stage time-limited protection responds to the high-voltage plant bus grounding fault (see Figure 1 Fault point 2), zero-sequence II stage time-limit protection responds to the ground fault between the low-voltage side winding common box busbar of the high-voltage plant transformer and the incoming circuit breaker (see Figure 1 Fault point 1).
[0003] According to Article 4.3.2 of DL / T 1502-2016 "Guidelines for Calculation of Setting of Auxiliary Power Relay Protection", for the neutral point low-resistance grounding system, the zero-sequence overcurrent protection output mode of the neutral point on the low-voltage side of the high-voltage auxiliary transformer is set as follows: the branch zero-sequence I stage time limit action is to trip the branch circuit breaker and lock the backup power supply switching; the branch zero-sequence II stage time limit action is to shut down and start the backup power supply switching.
[0004] The branch zero-sequence I stage blocking the backup power supply switching can prevent the backup power supply from being mistakenly put into the faulty busbar, so that the primary equipment can avoid being hit by the fault again; when a ground fault occurs between the low-voltage side winding common box busbar of the high-voltage plant transformer and the incoming circuit breaker, the branch zero-sequence I stage protection will be activated first, and the outlet will jump to the branch circuit breaker, lock the quick-cut device and wait for manual reset, but the fault point has not been removed, and the fault current still exists. After the branch zero-sequence II stage delay, the protection stage II will act at full stop and start the plant power quick-cut, but the quick-cut device is still in the waiting reset state at this time, and manual reset is required to make the quick-cut device ready. Therefore, the "start quick-cut" instruction of the II stage protection outlet has no practical meaning, and the plant power switching cannot be started, which will eventually cause the unit plant busbar power supply to lose power, causing the important auxiliary equipment of the power plant to lose working power, affecting the safe shutdown of the unit, and even causing damage to important primary equipment.
[0005] Therefore, the present invention proposes an optimization method for coordinating the branch zero-sequence protection outlet with the quick-cut device, which can solve the above-mentioned problem.
[0006] After searching, no public documents of the prior art identical or similar to the present invention were found. Summary of the invention
[0007] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an optimization method for the coordination between a branch zero-sequence protection outlet and a quick-cutting device. When a grounding fault occurs between the common box busbar of the low-voltage side winding of the high-voltage plant transformer of a power plant and the incoming circuit breaker, the problem that the quick-cutting device cannot be started after the branch zero-sequence overcurrent II stage protection is actuated can be solved by optimizing the application of the coordination between the tripping outlet of the branch zero-sequence overcurrent I stage protection and the action of the plant power quick-cutting device.
[0008] The present invention solves the practical problem by adopting the following technical solutions:
[0009] An optimization method for the coordination between a branch zero-sequence protection outlet and a quick-cut device comprises the following steps:
[0010] Step 1: Change the new export mode of the high-voltage transformer branch zero-sequence protection stage I to "jump high-voltage transformer branch switch" and "locking switch";
[0011] Step 2: Use the spare core of the cable from the generator-transformer group protection cabinet to the quick-cut device, and connect the newly added output relay TJ27 contact to the spare input 511 of the quick-cut device through the output pressure plate, as the input of the "locking switch" of the quick-cut device;
[0012] Step 3. The quick-cut device is upgraded through software logic. When the newly added "locked quick-cut" input 511 is received, only the position change start and the pressure loss start are locked, and the quick-cut device does not discharge. The function of zero-sequence I stage protection locked quick-cut can be realized. At the same time, when the zero-sequence II stage protection start input is received again, the quick-cut can be started quickly.
[0013] Moreover, the specific steps of step 1 include:
[0014] (1) The original output modes of the high-voltage transformer branch zero-sequence protection stage I are "jump high-voltage transformer branch switch" and "protection lockout quick cut". The spare output relay of the generator-transformer group protection is used as the new output mode "lockout switching" of the high-voltage transformer branch zero-sequence protection stage I, and the new output "lockout switching" of the high-voltage transformer branch zero-sequence protection stage I is added by changing the output mode control word.
[0015] (2) By changing the export mode control word, cancel the "protection lockout quick cut" of the original export mode of the high-voltage transformer branch zero-sequence protection stage I;
[0016] (3) After the above modification, the new exit mode of the high-voltage transformer branch zero-sequence protection section I is "jumping the high-voltage transformer branch switch" and "locking switching".
[0017] Advantages and beneficial effects of the present invention:
[0018] 1. The present invention provides an optimization method for the coordination of the zero-sequence overcurrent protection outlet and the plant power quick-cut device, which is reasonably designed, simple, economical and easy to use. In this optimization method, since the zero-sequence current I-stage protection outlet is no longer connected to the "protection lock" input of the quick-cut device, the quick-cut device will not be locked after the protection action trips the branch circuit breaker, and no manual reset signal is required. In addition, the abnormal lockout quick-cut time delay of the switch position is fixedly set to 10 seconds, and the zero-sequence II-stage protection action time is much less than 10 seconds. Therefore, when the zero-sequence I-stage protection action trips the working branch, and the standby branch is not closed, it is ensured that the quick-cut device will not be locked.
[0019] 2. The optimization method of the present invention fundamentally solves the problem that the quick-cut device cannot be started after the plant branch zero-sequence II stage protection is actuated. The plant quick-cut device adds a new "locking switch" input as the branch zero-sequence I stage protection action signal, which only locks the switch position change start and the pressure loss start, and opens the protection start within a certain period of time. The quick-cut device does not discharge. When the quick-cut start instruction is received again (i.e., the zero-sequence protection II stage is actuated), the quick-cut start function can be automatically completed to ensure that the high-voltage plant bus does not lose power.
[0020] 3. The secondary circuit of the present invention is simple and convenient to connect. The generator-transformer group protection adds a group of outlets as the "locking switch" input of the fast-cut device (such as Figure 2 As shown, 511 is the newly added "locking switch" entry point), the hard wiring transformation can be achieved by using only a spare core of the original cable from the protection device to the quick-cut device.
[0021] 4. The principle of the domestic quick-cut device in the present invention is similar. By changing the software logic and utilizing the newly added "locked quick-cut" to only lock the position change start and the pressure loss start, the quick-cut device does not discharge, and the function of zero-sequence I stage protection locked quick-cut can be realized, which is easy to promote and apply. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 A schematic diagram of a grounding fault in a high-voltage plant system of the present invention;
[0023] Figure 2 A circuit diagram for the quick-cut device of the present invention;
[0024] Figure 3 This is a schematic diagram of the tripping output matrix of the high-voltage transformer substation branch protection before the optimization method of the present invention is implemented;
[0025] Figure 4 This is a schematic diagram of the tripping output matrix of the high-voltage transformer substation branch protection after the optimization scheme of the present invention is implemented;
[0026] Figure 5 It is the protection outlet and quick cut-in circuit diagram of the present invention. DETAILED DESCRIPTION
[0027] The embodiments of the present invention are further described in detail below with reference to the accompanying drawings:
[0028] An optimization method for the coordination between a branch zero-sequence protection outlet and a quick-cut device comprises the following steps:
[0029] Step 1: Change the new export mode of the high-voltage transformer branch zero-sequence protection stage I to "jump high-voltage transformer branch switch" and "locking switch";
[0030] The specific steps of step 1 include:
[0031] (1) The original output mode of the zero-sequence protection of the high-voltage transformer branch I is "jumping the high-voltage transformer branch switch" ( Figure 3 TJ9), "Protection Lock Quick Cut" ( Figure 3 TJ14); using the spare output relay of the generator-transformer group protection, ( Figure 3 TJ27), as the new output mode "locking switch" of high-voltage transformer branch zero-sequence protection section I, and by changing the output mode control word, a new output "locking switch" of high-voltage transformer branch zero-sequence protection section I is added ( Figure 4 TJ27);
[0032] (2) By changing the export mode control word, cancel the "protection lock fast cut" of the original export mode of the high-voltage transformer branch zero-sequence protection I section, that is, Figure 4 TJ14 of the zero sequence I section of the high-voltage transformer branch is changed from "1" to "0";
[0033] (3) After the above modification, the new exit mode of the high-voltage transformer branch zero-sequence protection stage I is "tripping the high-voltage transformer branch switch" and "locking switching", that is, Figure 4 Set TJ9 and TJ27 of the zero sequence I section of the high-voltage transformer branch to "1". ;
[0034] Step 2: Use the spare cable core from the generator-transformer protection cabinet to the quick-cut device, such as Figure 5 As shown, the newly added output relay TJ27 contact is connected to the spare input 511 of the quick-cut device through the output pressure plate, serving as the input of the "locking switch" of the quick-cut device.
[0035] Step 3. The quick-cut device is upgraded through software logic. When the newly added "locked quick-cut" input 511 is received, only the position change start and the pressure loss start are locked, and the quick-cut device does not discharge. The function of zero-sequence I stage protection locked quick-cut can be realized. At the same time, when the zero-sequence II stage protection start input is received again, the quick-cut can be started quickly.
[0036] The working principle of the present invention is:
[0037] When a ground fault occurs in the high-voltage transformer branch, after the branch zero-sequence I-stage protection is actuated to trip the high-voltage transformer working branch switch, the quick-cut switch will trip incorrectly or start the quick-cut due to loss of pressure. Therefore, according to this idea, the quick-cut device can be upgraded through software. When receiving a new "switching lock" 511 input (i.e., the branch zero-sequence I-stage protection action output), the switch position start and loss of pressure start functions are immediately locked, and the protection start function is still open, and the device does not discharge. If the high-voltage transformer ground fault is still not eliminated within a certain period of time, the branch zero-sequence protection II-stage protection will be actuated at this time, and a quick-cut start instruction will be issued, which can automatically complete the quick-cut start function to ensure that the high-voltage plant bus does not lose power.
[0038] The process before and after optimization of the coordination behavior between the zero-sequence protection outlet of the high-voltage transformer substation branch and the quick-cut device is as follows:
[0039] (1) When Figure 1 Fault point 2-When the high-voltage plant bus fails:
[0040] Before optimization: After the branch zero-sequence overcurrent I stage (delay t1) is activated, Figure 3 It can be seen that the TJ9 tripping output relay trips the working branch switch ( Figure 1-1 DL circuit breaker), at the same time, the TJ14 tripping relay is sent to the quick-cut device to open the 502 "protection lock quick-cut" contact to connect, the protection lock quick-cut device, and the device sends a lock signal waiting for manual reset.
[0041] After optimization: After the branch zero-sequence overcurrent I stage (delay t1) is actuated, Figure 4 It can be seen that the TJ9 tripping output relay trips the working branch switch ( Figure 1-1 DL circuit breaker), and at the same time, TJ27 tripping relay is actuated to the quick-cut device to open the 511 "locked quick-cut" contact to connect, and immediately lock the position change starting and pressure loss starting of the quick-cut device inside the quick-cut device. Because the fault point is on the factory bus, the fault current disappears after the 1DL circuit breaker trips, and the fault is removed. After a delay of 10 seconds, a "locked quick-cut" alarm signal is issued to wait for manual reset.
[0042] (2) When Figure 1 Fault point 1- When a fault occurs between the low-voltage side winding common box busbar of the high-voltage plant transformer and the incoming circuit breaker:
[0043] Before optimization:
[0044] 1. First, the zero-sequence overcurrent I stage (delay t1) of the branch is activated. Figure 3 It can be seen that the TJ9 tripping output relay trips the working branch switch ( Figure 1-1 DL circuit breaker), at the same time, TJ14 tripping relay is sent to the quick-cut device to open the 502 "protection lock quick-cut" contact to connect, the protection lock protection lock quick-cut device, and the device sends a lock signal waiting for manual reset.
[0045] 2. Because the fault point is between the low-voltage side winding common box busbar of the high-voltage plant transformer and the incoming line circuit breaker, although the 1DL circuit breaker is disconnected, the fault current still exists. Therefore, after the branch zero-sequence overcurrent II stage delay t2 (t2>t1), the branch zero-sequence II stage protection is activated and the "start fast cut" instruction is issued ( Figure 3 / Figure 4 TJ13), but because the quick-cut device needs to be manually reset, it cannot be started. At this time, the plant bus loses power, causing the important plant auxiliary machines on this bus to lose power, resulting in a series of serious consequences that threaten the safe operation of the unit.
[0046] After optimization: First, the zero-sequence overcurrent I stage (delay t1) is activated, and then Figure 4 It can be seen that the TJ9 tripping output relay trips the working branch switch ( Figure 1-1 DL circuit breaker), and at the same time, the TJ27 tripping relay is actuated to the quick-cutting device to open the 511 "locked quick-cut" contact to connect, and the position change start and voltage loss start of the quick-cutting device are immediately locked inside the quick-cutting device, but the protection start is still open. Because the fault point is between the low-voltage side winding common box busbar of the high-voltage plant transformer and the incoming circuit breaker, although the 1DL circuit breaker is disconnected, the fault current still exists, so after the branch zero-sequence overcurrent II stage delay t2 (t2>t1), the branch zero-sequence II stage protection is actuated, and the TJ13 tripping output relay is actuated to the quick-cutting device to open the 501 "protection start" contact to connect, and the quick-cutting device immediately starts the quick cut and closes. Figure 1 The 2DL spare branch circuit breaker was used and the factory busbar resumed power supply.
[0047] It should be emphasized that the embodiments of the present invention are illustrative rather than restrictive. Therefore, the present invention includes but is not limited to the embodiments described in the specific implementation modes. Any other implementation modes derived by those skilled in the art based on the technical solutions of the present invention also fall within the scope of protection of the present invention.
Claims
1. An optimization method for the coordination between a branch zero-sequence protection outlet and a quick-cut device, characterized in that: The following steps are involved: Step 1: Change the new export mode of the high-voltage transformer branch zero-sequence protection stage I to "jump high-voltage transformer branch switch" and "locking switch"; Step 2: Use the spare core of the cable from the generator-transformer protection cabinet to the quick-cut device, and connect the newly added output relay TJ27 contact to the spare input 511 of the quick-cut device through the output pressure plate, as the input of the "locking switch" of the quick-cut device; Step 3. The quick-cut device is upgraded through software logic. When the newly added "locked quick-cut" input 511 is received, only the position change start and the pressure loss start are locked, and the quick-cut device does not discharge. The function of zero-sequence I stage protection locked quick-cut can be realized. At the same time, when the zero-sequence II stage protection start input is received again, the quick-cut can be started quickly.
2. The optimization method for the coordination between the branch zero-sequence protection outlet and the quick-cut device according to claim 1 is characterized in that: The specific steps of step 1 include: (1) The original output modes of the high-voltage transformer branch zero-sequence protection stage I are "jump high-voltage transformer branch switch" and "protection lockout quick cut". The spare output relay of the generator-transformer group protection is used as the new output mode "lockout switching" of the high-voltage transformer branch zero-sequence protection stage I, and the new output "lockout switching" of the high-voltage transformer branch zero-sequence protection stage I is added by changing the output mode control word. (2) Cancel the "protection lockout quick cut" of the original export mode of the high-voltage transformer branch zero-sequence protection section I by changing the export mode control word; (3) After the above modifications, the new exit modes of the high-voltage transformer branch zero-sequence protection section I are "jumping the high-voltage transformer branch switch" and "locking switching".