A method for checking the matching of contactor inherent delay and zero-sequence protection time setting

Abstract

The present invention discloses a method for checking the matching of the inherent time delay of a contactor and the setting of the zero-sequence protection time, including selecting a vacuum contactor switch as a test object and confirming that safety measures are well implemented, combining the test design with the temporary vacuum contactor switch closing circuit wiring and setting the state sequence logic of a microcomputer relay protection tester, and then simulating the action and opening of the switch when the switch is closed to a ground fault. By sequentially setting different zero-sequence protection action time constants of the switch, repeatedly simulating the test of closing the switch to a ground fault for multiple times and analyzing and recording the inherent delay time of the switch opening, the matching relationship between the inherent delay of the vacuum contactor switch opening and the setting value of the zero-sequence protection action time is checked, avoiding the hidden danger of protection over-tripping caused by the switch opening delay when a ground short circuit fault occurs at the moment of the switch closing, improving the reliability of the equipment operation, and providing a strong guiding basis for the reasonable setting of the zero-sequence protection action time constant of the switch.

Description

Technical Field

[0001] The invention belongs to the technical field of the breaking and closing capabilities of high-voltage vacuum contactors in power plants and the matching of the breaking and closing capabilities with protection setting values, and in particular relates to a method for checking the matching of the inherent delay of a contactor and the zero-sequence protection time setting. Background Art

[0002] Vacuum contactor switches are important control equipment in power systems. There are a large number of vacuum contactor switches in thermal power plants or power grids, and the operating conditions and technical requirements are relatively complex. Their operating reliability is not only related to the vacuum contactor itself, but also affects other equipment and even the entire power system. Therefore, it is an extremely important task to test the breaking and closing ability of vacuum contactor switches. When the action characteristics of vacuum contactor switches are tested by traditional methods, only the mechanical characteristics of the switch during normal opening and closing can be reflected, such as the opening and closing time, number of bounces and travel of the switch, etc., but the corresponding characteristics of the switch during opening and closing in special ways or under extreme conditions cannot be fully reflected. For example, when a single-phase grounding fault occurs at the moment of closing the switch, if there is still residual magnetism in the closing coil of the switch, the action opening characteristics of the switch will be affected to a certain extent, and there will be a hidden danger of protection over-tripping due to the delay of the vacuum contactor switch opening. For example, in 2018, a power plant experienced a power outage in the 6kV working section of a unit. The reason was that the load on the bus section had a single-phase grounding fault and the vacuum contactor switch exceeded the fault removal time limit, causing the bus incoming line switch to trip. The vacuum contactor switch had a single-phase grounding fault at the moment of closing. The zero-sequence overcurrent protection of the switch integrated protection device delayed 0.1S to operate the output. The inherent time of the vacuum contactor switch to open due to closing at the fault was 0.75S. After the zero-sequence overcurrent protection was activated, the vacuum contactor switch did not trip according to the set delay of 0.1S. The upper-level incoming line switch failed to avoid the fault removal time when the vacuum contactor switch failed at the moment of closing due to the set action delay of 0.7S, resulting in the protection over-operation, resulting in bus power outage and unit load shedding. After investigation, it was found that vacuum contactors generally have a long opening delay time after closing at a short-circuit fault.

[0003] Therefore, how to verify the inherent delay of the vacuum contactor switch closing and opening after a fault has become an urgent problem to be solved in thermal power plants at this stage. In the existing technology, there is currently a lack of effective solutions to the problem of matching the inherent delay of the vacuum contactor with the zero-sequence protection time setting. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for checking the matching of the inherent delay of the contactor and the zero-sequence protection time setting, thereby avoiding the hidden danger of protection over-tripping caused by the inherent opening delay of the vacuum contactor switch and improving the reliability of equipment operation.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for checking the matching of contactor inherent delay and zero-sequence protection time setting, characterized in that it comprises the following steps:

[0007] S1: Select the vacuum contactor switch on the bus section as the target, disconnect the control power of the switch and confirm that the switch is in the open state of the test position;

[0008] S2: Build a temporary vacuum contactor switch closing circuit connection and set the zero-sequence protection setting value of the switch integrated protection device;

[0009] S3: Set the state sequence logic of the microcomputer relay protection tester to simulate the action and opening of the switch when the switch is closed due to a ground fault;

[0010] S4: Set different zero-sequence protection action time settings for the switch, record and analyze the inherent delay time of the switch opening to perform matching verification.

[0011] Furthermore, in step S1, the vacuum contactor needs to disconnect the DC control power supply of the switch, and the secondary control plug of the switch is tightly connected.

[0012] Furthermore, the model of the vacuum contactor is HN46AY-41.

[0013] Furthermore, in the step S2, the closing control circuit of the vacuum contactor switch is temporarily bridged, and the negative end of the closing coil of the switch needs to be bridged to the negative pole of the DC control power supply, and the positive end of the closing coil needs to be connected in series with a normally open dry contact and bridged to the positive pole of the DC control power supply.

[0014] Furthermore, the normally open dry contacts adopt any set of switch output contacts of a microcomputer relay protection tester.

[0015] Furthermore, the switch integrated protection device adopts the model of CSC-237A, and the zero-sequence protection current action value I 0 =0.4A, action time T 0 It is adjusted to 0.1S-0.6S according to the actual needs on site.

[0016] Furthermore, the microcomputer relay protection tester in step S3 needs to complete the wiring work of the relay protection tester.

[0017] Connect the three-phase current output contact test line I A ,I B ,I C and I NThey are respectively connected to the corresponding three-phase load current terminal blocks in the switch control cabinet. When wiring, the current terminal block connector needs to be disconnected to isolate the load current transformer body side from the switch integrated protection device side. The three-phase current output contact test lines of the relay protection tester are respectively connected to the switch integrated protection device side;

[0018] Select a set of switch output contacts A of the relay protection tester as the normally open dry contacts for the vacuum contactor switch closing control, and connect its two test wires to the positive pole of the switch DC control power supply and the positive terminal of the switch closing coil respectively;

[0019] A set of switch input contacts A of the relay protection tester are selected as feedback contacts for returning the action and opening time of the switch, and its two test lines are respectively connected to the two ends of the auxiliary normally open contacts of the switch; after the relay protection tester is powered on, the action and opening characteristics of the switch when it is closed on a ground fault are simulated by executing the state sequence logic program, and the action and opening time of the switch is returned.

[0020] Furthermore, the state sequence logic setting of the microcomputer relay protection tester consists of two states, wherein the state one parameter is set to the three-phase voltage and current amplitudes are all 0, the relay protection tester is set to the switch output contact A closed for vacuum contactor switch closing control, the end mode of state one is set to the switch input contact A closed, the switch auxiliary contact feedback closed, and the delay after state one is triggered is set to 0.005S, which is used as a buffer process time after the switch action; the state two parameter is set to the three-phase voltage amplitudes are all 0, the current amplitude A phase is set to 0.42A, B and C phases are both set to 0, the switch output contact A remains in the disconnected state, and the end mode of state two is set to the switch input contact A disconnected, and the switch auxiliary contact feedback open.

[0021] Furthermore, in step S4, the zero-sequence protection current action value is kept at 0.4A and remains unchanged, and the zero-sequence protection action time T of the switch is set to 0 The zero-sequence protection action time constants are set to 0.1S, 0.2S, 0.3S, 0.4S, 0.5S and 0.6S respectively. Each time the zero-sequence protection action time constant is modified, the simulation of the action and opening test of the switch when closing the switch on a ground fault is repeated multiple times, and the returned switch action and opening time is recorded in sequence.

[0022] Furthermore, the difference ΔT obtained by subtracting the set zero-sequence protection action time setting value from the recorded returned switch action opening time is the inherent delay time of the switch opening. When the switch is operating normally, ΔT must be less than 100mS to meet the on-site equipment operation requirements. By repeatedly performing switch action opening tests, the matching between the zero-sequence protection action time setting value and the switch action opening inherent delay time can be verified.

[0023] Compared with the prior art, the present invention has the following beneficial technical effects:

[0024] The present invention provides a method for checking the matching of the inherent time delay of a contactor and the setting of the zero-sequence protection time. By selecting a vacuum contactor switch as a test object and confirming that safety measures are well implemented, a temporary vacuum contactor switch closing circuit wiring is designed in combination with the test and the state sequence logic of a microcomputer relay protection tester is set, thereby simulating the action and opening of the switch when the switch is closed to a ground fault. By sequentially setting different zero-sequence protection action time constants of the switch, repeatedly simulating the test of closing the switch to a ground fault for multiple times and analyzing and recording the inherent time delay of the switch opening, the matching relationship between the inherent time delay of the vacuum contactor switch opening and the setting value of the zero-sequence protection action time is checked, thereby avoiding the hidden danger of the vacuum contactor switch causing the protection over-tripping due to the inherent time delay of opening, improving the reliability of the equipment operation, and providing a strong guiding basis for the reasonable setting of the zero-sequence protection action time constant of the switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of a method for checking the matching of the contactor's inherent delay and zero-sequence protection time setting according to the present invention;

[0026] Figure 2 The schematic diagram of the vacuum contactor switch control circuit is selected in the specific embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention is further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0028] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] A method for checking the matching of contactor inherent delay and zero sequence protection time setting, such as Figure 1 As shown, the following steps are included:

[0031] S1: Select the vacuum contactor switch on the bus section as the target, disconnect the control power of the switch and confirm that the switch is in the open state of the test position;

[0032] S2: Build a temporary vacuum contactor switch closing circuit connection and set the zero-sequence protection setting value of the switch integrated protection device;

[0033] S3: Set the state sequence logic of the microcomputer relay protection tester to simulate the action and opening of the switch when the switch is closed due to a ground fault;

[0034] S4: Set different zero-sequence protection action time settings for the switch, record and analyze the inherent delay time of the switch opening to perform matching verification.

[0035] Specifically, before the steps S1, S2, S3, and S4 are performed, the status of the selected load motor must be confirmed, and it must be checked that the load motor is in a shutdown state, its vacuum contactor switch is in the test position and is open, and it must be ensured that there is no maintenance work on the load equipment involved.

[0036] Preferably, the specific operation steps of steps S1, S2, S3 and S4 are:

[0037] (1) A technician in this field confirms that the DC 110V control power supply of the vacuum contactor switch is in the off state and that the secondary control plug of the switch is securely connected.

[0038] (2) A person skilled in the art temporarily bridges the closing control circuit of the vacuum contactor switch, bridges the negative terminal HZ- of the closing coil of the switch to the negative electrode 102 of the DC control power supply, and connects the positive terminal HZ+ of the closing coil in series with a normally open dry contact (Binary Output 1) of the switch quantity output of a microcomputer relay protection tester and then bridges it to the positive electrode 101 of the DC control power supply. Figure 2 As shown, one end of the normally open dry contact of the switch output of the microcomputer relay protection tester is connected to the terminal block 101, and the other end is connected to the terminal block 103.

[0039] (3) A technician in this field performs test wiring on the microcomputer relay protection tester and connects the three-phase current output contact I A ,I B ,I C and I N Use test lines to connect to the corresponding three-phase load current terminal blocks in the switch control cabinet. When wiring, disconnect the current terminal block connector to isolate the current transformer body side of the load from the switch integrated protection device side. Check and confirm that the three-phase current output contact test lines of the relay protection tester are connected to the switch integrated protection device side.

[0040] (4) A technician in this field selects a set of normally open dry contacts (BinaryOutput 1) of the relay protection tester for the closing control of the vacuum contactor switch, and connects the two ends of the normally open dry contacts to the positive terminal 101 of the switch DC control power supply and the terminal 103 of the positive terminal HZ+ of the switch closing coil using test wires.

[0041] (5) A technician in this field selects a set of switch input contacts (Binary IutputA) of the relay protection tester as feedback contacts for returning the action opening time of the switch, and connects the two ends of the contacts to the two ends of the closing position contacts X3-1 and X3-2 of the switch respectively using test lines.

[0042] (6) A person skilled in the art sets the state sequence logic of the relay protection tester, wherein the state 1 parameter is set to 0 for the three-phase voltage and current amplitudes, 50HZ for the frequency, the relay protection tester output is set to close the binary output contact (Binary Output 1) for the vacuum contactor switch closing control, and the end mode of state 1 is set to close the binary input contact (Binary Iutput A), that is, the switch closing position contact feedback returns to the position and executes the next state. In addition, a delay of 0.005S needs to be set after state 1 is triggered to serve as a buffer process time after the switch action.

[0043] (7) A person skilled in the art sets the state 2 parameters of the relay protection tester to the three-phase voltage amplitudes of 0, the current amplitude of phase A to 0.42A, the current amplitude of phases B and C to 0, and the switch output contact (Binary Output 1) to the disconnected state. The end mode of state 2 is set to the disconnection of the switch input contact (Binary Iutput A), that is, the test is terminated when the switch closing position contact is fed back to the open position.

[0044] (8) After the above steps are completed, the technicians in this field supply the DC 110V control power supply of the vacuum contactor switch to power on the switch integrated protection device, and adjust the zero-sequence protection setting value of the switch integrated protection device CSC-237A, and adjust the zero-sequence protection current action value I0 to 0.4A, and the action time T0 to 0.1S, 0.2S, 0.3S, 0.4S, 0.45S, 0.5S and 0.6S respectively.

[0045] (9) A technician in this field turns on the relay protection tester and runs it, and simulates the opening and closing of the switch when a ground fault occurs at the moment of closing the switch by executing the state sequence logic program, and records the opening and closing time of the returned switch.

[0046] (10) Keep the zero-sequence protection current action value of the switch integrated protection device unchanged at 0.4A, and adjust the zero-sequence protection action time constant T0 of the switch to 0.1S, 0.2S, 0.3S, 0.4S, 0.5S and 0.6S in sequence. Each time the zero-sequence protection action time constant is set, repeat the simulation of the switch closing action and opening test when the ground fault occurs three times, and record the switch action and opening time of each return in sequence.

[0047] (11) The difference ΔT obtained by subtracting the set zero-sequence protection action time setting value T0 from the returned switch action opening time is the inherent delay time of the switch action. Generally, ΔT must be less than 100mS to meet the on-site operation requirements of the equipment. The matching between the zero-sequence protection action time setting value and the switch action opening inherent delay time can be verified by repeatedly performing the switch action opening test, as shown in Table 1.

[0048] Table 1

[0049]

[0050] From the inherent delay time of the switch opening in the table, by setting different zero-sequence protection action time settings to check the inherent delay time of the switch opening, it can be seen that when the zero-sequence protection current action setting of the switch is 0.4A and the action time is 0.45S, the inherent delay time of the switch opening is within 100mS, and the switch opening action characteristics are qualified. Therefore, it can be verified that the setting critical value of the switch zero-sequence protection action time is 0.45S. Only when the setting value of the switch zero-sequence protection action time is greater than 0.45S, the switch can reliably realize the closing and opening actions.

[0051] (12) After the test is completed, the technical personnel in charge will restore the test wiring of the switch and put the switch into hot standby mode.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for checking the matching of contactor inherent delay and zero-sequence protection time setting. It is characterized in that The following steps are involved: S1: Select the vacuum contactor switch on the bus section as the target, disconnect the control power of the switch and confirm that the switch is in the open state of the test position; S2: Build a temporary vacuum contactor switch closing circuit connection and adjust the zero-sequence protection setting of the switch integrated protection device; whereby temporarily bridge the closing control circuit of the vacuum contactor switch, the negative end of the switch closing coil needs to be bridged to the negative pole of the DC control power supply, and the positive end of the closing coil needs to be connected in series with a normally open dry contact and bridged to the positive pole of the DC control power supply; S3: Set the state sequence logic of the microcomputer relay protection tester to simulate the action and opening of the switch when the switch is closed due to a ground fault; S4: Set different zero-sequence protection action time settings for the switch, record and analyze the inherent delay time of the switch opening to perform matching verification.

2. According to the method for checking the matching of the contactor inherent delay and zero-sequence protection time setting as described in claim 1, It is characterized in that In step S1, the vacuum contactor needs to disconnect the DC control power supply of the switch, and the secondary control plug of the switch is tightly connected.

3. According to the method for checking the matching of the contactor inherent delay and zero-sequence protection time setting as described in claim 1, It is characterized in that The model of the vacuum contactor is HN46AY-41.

4. According to the method for checking the matching of the contactor inherent delay and zero-sequence protection time setting as described in claim 1, It is characterized in that The normally open dry contacts adopt any group of switch output contacts of the microcomputer relay protection tester.

5. According to the method for checking the matching of the contactor inherent delay and zero-sequence protection time setting as described in claim 1, It is characterized in that The switch integrated protection device adopts CSC-237A, and the zero-sequence protection current action value I 0 =0.4A, action time T 0 It is adjusted to 0.1S-0.6S according to the actual needs on site.

6. According to the method for checking the matching of the contactor inherent delay and zero-sequence protection time setting as described in claim 1, It is characterized in that The microcomputer relay protection tester in step S3 needs to complete the wiring work of the relay protection tester. Connect the three-phase current output contact test line I A ,I B ,I C and I N They are respectively connected to the corresponding three-phase load current terminal blocks in the switch control cabinet. When wiring, the current terminal block connector needs to be disconnected to isolate the load current transformer body side from the switch integrated protection device side. The three-phase current output contact test lines of the relay protection tester are respectively connected to the switch integrated protection device side; Select a set of switch output contacts A of the relay protection tester as the normally open dry contacts for the vacuum contactor switch closing control, and connect its two test wires to the positive pole of the switch DC control power supply and the positive terminal of the switch closing coil respectively; A set of switch input contacts A of the relay protection tester are selected as feedback contacts for returning the action and opening time of the switch, and its two test lines are respectively connected to the two ends of the auxiliary normally open contacts of the switch; after the relay protection tester is powered on, the action and opening characteristics of the switch when it is closed on a ground fault are simulated by executing the state sequence logic program, and the action and opening time of the switch is returned.

7. According to claim 6, a method for checking the matching of contactor inherent delay and zero-sequence protection time setting, It is characterized in that The state sequence logic setting of the microcomputer relay protection tester consists of two states, wherein the state one parameter is set to the three-phase voltage and current amplitudes are all 0, the relay protection tester is set to the switch output contact A closed for vacuum contactor switch closing control, the end mode of state one is set to the switch input contact A closed, the switch auxiliary contact feedback closed, and the delay is set to 0.005S after state one is triggered, which is used as a buffer process time after the switch action; the state two parameter is set to the three-phase voltage amplitudes are all 0, the current amplitude A phase is set to 0.42A, B and C phases are both set to 0, the switch output contact A remains in the disconnected state, and the end mode of state two is set to the switch input contact A disconnected, and the switch auxiliary contact feedback open.

8. According to the method for checking the matching of the contactor inherent delay and zero-sequence protection time setting as described in claim 1, It is characterized in that In step S4, the zero-sequence protection current action value is kept at 0.4A and remains unchanged, and the zero-sequence protection action time T of the switch is set to 0 The zero-sequence protection action time constants are set to 0.1S, 0.2S, 0.3S, 0.4S, 0.5S and 0.6S respectively. Each time the zero-sequence protection action time constant is modified, the simulation of the action and opening test of the switch when closing the switch on a ground fault is repeated multiple times, and the returned switch action and opening time is recorded in sequence.

9. According to claim 8, a method for checking the matching of contactor inherent delay and zero-sequence protection time setting, It is characterized in that The difference ∆T obtained by subtracting the set zero-sequence protection action time setting value from the recorded return switch action opening time is the inherent delay time of the switch opening. When the switch is operating normally, ∆T must be less than 100mS to meet the on-site equipment operation requirements. By repeatedly performing switch action opening tests, the matching between the zero-sequence protection action time setting value and the switch action opening inherent delay time can be verified.

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