Main transformer protection tripping outlet automatic switching device and method

Abstract

The invention provides a main transformer protection tripping outlet automatic switching device, and the system comprises a disconnecting link position detection unit which is used for collecting the position signal of a bus disconnecting link hung on a current main transformer high-voltage side switch; the tripping control units are connected to the section switches respectively, each tripping control unit comprises a switching relay linked with the corresponding bus disconnecting link, and the switching relays are automatically controlled to be switched on and off according to bus disconnecting link position signals; the state indication unit is used for controlling the on / off of an indication lamp according to the on / off of the switching relay in each tripping control unit so as to display the on / off state of the corresponding tripping outlet pressing plate; and the disconnecting link operation locking unit locks the operation of the disconnecting link when the disconnecting link gives a low-air-pressure alarm. The invention further discloses a corresponding method. According to the invention, the switching-on and switching-off of the tripping outlet pressing plate can be automatically switched according to the switching-on and switching-off position of the bus disconnecting link, indication is carried out, and the safety and the operation and maintenance efficiency of a power system are improved.

Description

Technical Field

[0001] This invention relates to the field of trip protection technology for double busbar and double-section busbar structures, and particularly to an automatic switching device and method for trip output of main transformer protection. Background Technology

[0002] like Figure 1 As shown, in a 220kV power system with a double busbar and double-section busbar structure, based on the double busbar connection, two sectionalizing switches divide each of the two busbars into two sections, forming four busbar sections (1M, 3M, 2M, 4M), and two bus tie switches are configured. For example, the 220kV distribution equipment of a 500kV substation adopts this structure, achieving flexible connection through sectionalizing switches (the first and second sectionalizing switches in the figure) and bus tie switches (the first and second bus tie switches in the figure).

[0003] Understandably, in a double-bus, double-section wiring configuration, the sectionalizing switches and bus tie switches, as key connection and switching devices, have tripping control circuits that are a fundamental requirement for power system relay protection configurations. Each switch is equipped with an independent tripping circuit to ensure that, in the event of a fault, the protection device can accurately control the tripping operation of a specific switch, thereby isolating the faulty area.

[0004] According to the relay protection configuration requirements, manual on-site switching is required between the tripping circuit of the second section switch and the tripping circuit of the first section switch of the backup protection of the #1 main transformer, depending on the different busbars connected to the high-voltage switch of the main transformer. The switching instructions are as follows: like Figure 1 As shown, when the #1 main transformer high-voltage switch is connected to 220kV 1M operation (i.e., 1M disconnector 1G is closed and 2M disconnector 2G is opened), according to the protection configuration requirements, the tripping circuit of the first section switch and the first bus tie switch of the #1 main transformer backup protection tripping should be activated, and the tripping circuit of the second section switch of the #1 main transformer backup protection tripping should be disconnected.

[0005] Figure 2 for Figure 1The circuit diagram shows the trip control circuit of the circuit breaker. Each section switch has a trip control circuit based on the same principle. The traditional switching method involves manually engaging the "first pressure plate" in the first section switch's trip circuit and disengaging the "second pressure plate" in the second section switch's trip circuit. Note that the pressure plate corresponding to the first bus tie switch is normally engaged and is not included in this switching. In the circuit diagram, the closing position relay (HWJ) is a key component for monitoring the circuit breaker's closing status; the trip coil (TQ) generates a magnetic field after receiving an electrical signal, driving the circuit breaker to open; the protection output switching relay (TJ) is controlled by the protection device and closes to connect the trip circuit in case of a fault; the anti-pumping relay (TBJ) prevents the circuit breaker from reversing due to control contact sticking; the circuit breaker auxiliary contact (DL) reflects the circuit breaker's position status and is used to cut off the trip current. Pressure plates (such as the "first pressure plate") are used as interfaces for manually engaging and disengaging the circuit, enabling switching of operating modes.

[0006] Similarly, such as Figure 1 As shown, when the #1 main transformer high-voltage switch is connected to 220kV 2M operation (i.e., 2M disconnector 2G is closed, 1M disconnector 1G is open), the tripping circuits of the #1 main transformer backup protection interlocking second section switch and the first bus tie switch need to be activated, and the tripping circuit of the #1 main transformer backup protection interlocking first section switch needs to be disconnected. For example... Figure 2 As shown, similarly, it is necessary to manually engage the "second pressure plate" in the second section switch tripping circuit and disengage the "first pressure plate" in the first section switch tripping circuit.

[0007] However, the existing manual operation method has the following shortcomings: Traditional switching methods usually rely on manual operation, which is inefficient and prone to delays due to human negligence or insufficient skills, leading to malfunctions or failures of the protection device.

[0008] Manual operation carries the risk of misoperation, and the lack of corresponding indicator lights to remotely monitor whether the pressure plate switching is correct may lead to serious power system failures.

[0009] Under complex busbar operating conditions, the accuracy of manual judgment and operation is difficult to guarantee.

[0010] Therefore, developing a device that can automatically switch the backup protection tripping circuit of the main transformer is of great significance for improving the safety and reliability of the power system. Summary of the Invention

[0011] The technical problem to be solved by the present invention is that the present invention proposes an automatic switching device and method for the trip output of the main transformer protection, which can automatically switch the input and output of the trip output pressure plate according to the opening and closing position of the bus disconnect switch and provide indication, thereby improving the safety and operation and maintenance efficiency of the power system.

[0012] As one aspect of the present invention, an automatic switching device for the tripping output of the main transformer protection is provided, applicable to a 220kV double busbar double-section busbar structure, comprising: The disconnector position detection unit is used to collect the bus disconnector position signal of the current high-voltage side switch of the main transformer; Multiple trip control units are connected to each section switch. Each trip control unit includes a switching relay that is linked to its corresponding bus disconnect switch. The switching relay is connected in series to the trip circuit of its corresponding section switch. The switching relay is automatically controlled to open and close according to the bus disconnect switch position signal, thereby realizing the automatic activation and deactivation of the corresponding trip pressure plate. The status indicator unit is used to control the indicator lights to turn on and off according to the on and off states of the switching relays in each trip control unit, so as to display the on / off status of the corresponding trip output pressure plate in real time. The knife switch operation interlocking unit is used to lock the knife switch operation when a low air pressure alarm is triggered in the knife switch air chamber.

[0013] Preferably, the plurality of trip control units include: The first trip control unit includes a first sectionalizing switch trip circuit, which includes a pre-activated trip output first pressure plate; a first switching relay (ZJ4) is connected in series in the first sectionalizing switch trip circuit, and the first switching relay is controlled by the bus disconnector (1G) state of the 1M bus. The second trip control unit includes a second sectionalizing switch trip circuit, which includes a pre-activated trip output second pressure plate; a second switching relay (ZJ9) is connected in series in the second sectionalizing switch trip circuit, and the second switching relay is controlled by the bus disconnector (2G) state of the 2M bus. Specifically, when the busbar disconnector (1G) of the 1M busbar is closed and the busbar disconnector (2G) of the 2M busbar is open, the first switching relay (ZJ4) is energized, and its normally open contact closes, thus enabling the first sectionalizing switch tripping circuit to conduct; when the busbar disconnector (2G) of the 2M busbar is closed and the busbar disconnector (1G) of the 1M busbar is open, the second switching relay (ZJ9) is energized, and its normally open contact closes, thus enabling the second sectionalizing switch tripping circuit to conduct.

[0014] Preferably, the status indication unit includes: The low-voltage power supply is isolated from the high-voltage tripping circuit; LED indicator lights are connected in series with current-limiting resistors and then in parallel to the two ends of the corresponding trip output pressure plate; The LED indicator circuit is controlled to be on or off according to the status of the corresponding switching relay. When the trip circuit is on, the corresponding LED indicator lights up; otherwise, it turns off.

[0015] Preferably, the indicator light is a high-brightness LED; when the light is on, it indicates that the pressure plate is engaged, and when the light is off, it indicates that the pressure plate is disengaged.

[0016] Preferably, the disconnector operation interlocking unit is used to connect a normally open node for the low pressure signal of the disconnector air chamber in series in the disconnector control circuit. When the pressure of the disconnector air chamber is low, the disconnector control circuit is disconnected to prevent the disconnector from being operated; at the same time, the switching circuit where the disconnector is located is cut off to prevent the automatic switching device from switching automatically.

[0017] Accordingly, as another aspect of the present invention, an automatic switching device for the tripping output of the main transformer protection is also provided, which is implemented using the system described above, and includes the following steps: Collect the current bus disconnector position signal of the high-voltage side switch of the main transformer; The system automatically controls the switching relays in the trip control unit to open and close based on the busbar disconnector position signal, thereby enabling the automatic activation and deactivation of the corresponding trip pressure plate; thus, only the trip circuit matching the currently operating busbar is activated, while non-associated circuits are disconnected. The switching relays in each trip control unit are switched on and off, and the indicator lights are turned on and off to display the activation / deactivation status of the corresponding trip output pressure plate in real time.

[0018] Preferably, it further includes: The first trip output pressure plate in the first trip control unit and the second trip output pressure plate in the second trip control unit are put into operation once in the initial stage and kept in constant operation.

[0019] Preferably, the trip control unit automatically controls the switching relays in the trip control unit to open and close based on the busbar disconnector position signal, thereby achieving automatic activation and deactivation of the corresponding trip pressure plate, further including: When the busbar disconnector (1G) of the 1M busbar is closed and the busbar disconnector (2G) of the 2M busbar is open, the first switching relay (ZJ4) is energized, and its normally open contact closes, making the first sectionalizing switch tripping circuit conduct. At this time, when the air chamber pressure of the 2M busbar disconnector is low, the normally open contact 2GY1 of the 2M busbar disconnector air chamber pressure opens, cutting off the 2M busbar disconnector control circuit and prohibiting the 2M busbar disconnector from closing. At the same time, the normally open contact 2GY1 of the 2M busbar disconnector cuts off the switching circuit where the 2M busbar disconnector is located, preventing the second sectionalizing switch tripping circuit from conducting. When the busbar disconnector (2G) of the 2M busbar is closed and the busbar disconnector (1G) of the 1M busbar is open, the second switching relay (ZJ9) is energized, and its normally open contact closes, making the second sectional switch tripping circuit conduct. At this time, when the air chamber pressure of the 1M busbar disconnector is low, the normally open contact 1GY1 of the 1M busbar disconnector air chamber pressure is opened, cutting off the 1M busbar disconnector control circuit and prohibiting the 1M busbar disconnector from closing. At the same time, the normally open contact 1GY1 of the 1M busbar disconnector cuts off the switching circuit where the 1M busbar disconnector is located, preventing the first sectional switch tripping circuit from conducting.

[0020] Preferably, the indicator lights are controlled to turn on and off according to the switching relays in each trip control unit, so as to display the activation / deactivation status of the corresponding trip output pressure plate in real time, further including: The status indicator unit controls the on / off state of the corresponding LED indicator circuit according to the status of the switching relay. When the trip circuit pressure plate is engaged, the corresponding LED indicator lights up; otherwise, it turns off.

[0021] Implementing the embodiments of the present invention has the following beneficial effects: This invention provides an automatic switching device and method for the trip output of a main transformer protection system. By automatically detecting the open / close position signal of the busbar disconnector, the system automatically switches the trip output pressure plate on and off according to the open / close position of the busbar disconnector. The system also provides real-time indicator lights to remind on-site personnel of the current status of the pressure plate. This eliminates the need for manual switching of the pressure plate, thereby improving the safety and operation and maintenance efficiency of the power system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention. Figure 1 This is a schematic diagram of an existing 220kV double busbar double segmented busbar structure; Figure 2 for Figure 1 A schematic diagram of the circuit structure of a trip control unit; Figure 3 This is a schematic diagram illustrating the application environment of an automatic switching device for main transformer protection trip output provided by the present invention. Figure 4 for Figure 3 Schematic diagram of the circuit structure of the middle disconnect switch position detection unit; Figure 5 for Figure 3 A schematic diagram of the circuit structure of the first trip control unit in the circuit; Figure 6 for Figure 3 A schematic diagram of the circuit structure of the second trip control unit; Figure 7 for Figure 3 Schematic diagram of the control circuit structure of the intermediate disconnect switch; Figure 8 This is a schematic diagram of the main flow of an embodiment of the automatic switching method for tripping output of main transformer protection provided by the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0024] like Figure 3 The diagram shows an application environment schematic of the automatic switching device for main transformer protection trip output provided by the present invention; combined with... Figures 4 to 7 As shown, in this embodiment, the automatic switching device for the main transformer protection tripping output is applied to a 220kV double busbar double-section busbar structure, and includes: The disconnector position detection unit is used to collect the bus disconnector position signal of the current high-voltage side switch of the main transformer; Multiple trip control units are connected to each section switch. Each trip control unit includes a switching relay that is linked to its corresponding bus disconnect switch. The switching relay is connected in series to the trip circuit of its corresponding section switch. The switching relay is automatically controlled to open and close according to the bus disconnect switch position signal, thereby realizing the automatic activation and deactivation of the corresponding trip pressure plate. The status indicator unit is used to control the indicator lights to turn on and off according to the on and off states of the switching relays in each trip control unit, so as to display the on / off status of the corresponding trip output pressure plate in real time. The knife switch operation interlocking unit is used to lock the knife switch operation when a low air pressure alarm is triggered in the knife switch air chamber.

[0025] like Figure 4 As shown, it illustrates Figure 3 Schematic diagram of the circuit structure of the middle disconnect switch position detection unit; It is understood that, in the embodiments of the present invention, by inserting a 1M disconnector switching relay ZJ4 in series in the trip control circuit corresponding to each sectionalizing switch, and a 2M disconnector switching relay ZJ9 in series in the trip control circuit corresponding to the second sectionalizing switch, along with the corresponding low-voltage circuit, the trip circuit switching requirements can be automatically achieved without manual operation. This can be combined with... Figure 7 As shown.

[0026] like Figure 4As shown, when the main transformer high-voltage switch is connected to 220kV 1M operation (i.e., 1M disconnector 1G is closed, 2M disconnector 2G is open), the 1M disconnector switching circuit is activated, that is: power supply +——7QD1——7QD2——1G normally open contact (normally open contact is activated)——7QD4——R (current limiting resistor)——ZJ4 first switching relay——1M disconnector air chamber pressure contact 1GY1 (closed when the disconnector air chamber pressure is normal)——ZJ5 disconnector switching relay——332——7QD13——power supply—, the first switching relay ZJ4 is energized and its normally open contact is closed; similarly, the 2M disconnector switching relay (ZJ9) is not energized and its normally open contact is open. In this way, the opening and closing of the corresponding disconnector switching relay can be controlled by detecting the status of the corresponding disconnector.

[0027] like Figure 5 , Figure 6 As shown, a schematic diagram of the circuit structure of multiple trip control units is presented.

[0028] in, Figure 5 A schematic diagram of the circuit structure of the first trip control unit is shown.

[0029] Specifically, the first trip control unit includes a first sectionalizing switch trip circuit, which includes a pre-activated trip output first pressure plate; a first switching relay (ZJ4) is connected in series in the first sectionalizing switch trip circuit, and the first switching relay is controlled by the state of the bus disconnector (1G) of the 1M bus. When the busbar disconnector (1G) of the 1M busbar is closed and the busbar disconnector (2G) of the 2M busbar is open, the first switching relay (ZJ4) is energized, and its normally open contact closes, making the first sectional switch tripping circuit conduct. At this time, when the air chamber pressure of the 2M busbar disconnector is low, the normally open contact 2GY1 of the 2M busbar disconnector air chamber pressure is opened, cutting off the 2M busbar disconnector control circuit and prohibiting the 2M busbar disconnector from closing. At the same time, the normally open contact 2GY1 of the 2M busbar disconnector cuts off the switching circuit where the 2M busbar disconnector is located, preventing the second sectional switch tripping circuit from conducting. like Figure 5 As shown, because the current 1M disconnector 1G is closed, the normally open contact of the first switching relay (ZJ4) closes, causing the negative current circuit of the first sectionalizing switch trip circuit to automatically conduct. As long as the "protection trip" contact of the main transformer protection is open, the following occurs: +55V – protection trip – ZJ4 (normally open contact closed) – first pressure plate engaged – TBJ (anti-pump relay) – DL (automatically closes when the switch is closed) – TQ (trip coil) – -55V, first sectionalizing switch trips; At this time, because the normally open contact of the 2M knife switch switching relay (ZJ9) is open, the negative circuit of the second section switch tripping circuit is automatically disconnected (even if the "second pressure plate" is disconnected), and the protection will not connect the second section switch tripping circuit.

[0030] and Figure 6 A schematic diagram of the circuit structure of the first trip control unit is shown.

[0031] The second trip control unit includes a second sectionalizing switch trip circuit, which includes a pre-activated trip output second pressure plate; a second switching relay (ZJ9) is connected in series in the second sectionalizing switch trip circuit, and the second switching relay is controlled by the bus disconnector (2G) state of the 2M bus. When the busbar disconnector (2G) of the 2M busbar is closed and the busbar disconnector (1G) of the 1M busbar is open, the second switching relay (ZJ9) is energized, and its normally open contact closes, making the second section switch tripping circuit conduct. At this time, when the air chamber pressure of the 1M busbar disconnector is low, the normally open contact 1GY1 of the 1M busbar disconnector air chamber pressure is opened, cutting off the 1M busbar disconnector control circuit and prohibiting the 1M busbar disconnector from closing. At the same time, the normally open contact 1GY1 of the 1M busbar disconnector cuts off the switching circuit where the 1M busbar disconnector is located, preventing the first section switch tripping circuit from conducting. Its specific circuit structure is as follows Figure 6 As shown, when the main transformer high-voltage switch is connected to 220kV 2M operation (i.e., 2M disconnector 2G is closed, and 1M disconnector 1G is open), its switching principle is the same as... Figure 5 Similar descriptions are not elaborated upon here.

[0032] More specifically, in this embodiment of the invention, the status indication unit includes: The low-voltage power supply is isolated from the high-voltage tripping circuit; LED indicator lights are connected in series with current-limiting resistors and then in parallel to the two ends of the corresponding trip output pressure plate; The LED indicator circuit is controlled to be on or off according to the status of the corresponding switching relay. When the trip circuit is on, the corresponding LED indicator lights up; otherwise, it turns off.

[0033] The indicator light is a high-brightness LED. When the light is on, it means the pressure plate is engaged, and when the light is off, it means the pressure plate is disengaged, ensuring that on-site personnel can quickly and accurately identify the status of the pressure plate.

[0034] For the specific circuit structure, please refer to Figure 5 and Figure 6 The content within the dashed box. By adding indicator lights and corresponding low-voltage circuits to the first and second section switch trip control circuits, the indicator lights can intuitively show the current status (engaged or deactivated) of the trip output pressure plate to on-site personnel.

[0035] like Figure 5 As shown within the dashed box, when the main transformer high-voltage switch is connected to 220kV 1M operation (i.e., 1M disconnector 1G is closed, 2M disconnector 2G is open), the first switching relay ZJ4 is energized, and its normally open contact closes. This results in: + weak current input – indicator light – resistor – ZJ4 (normally open contact closed) – first pressure plate – - weak current output, with the indicator light illuminating, visually demonstrating to on-site personnel that the trip output pressure plate is in operation; similarly, extinguishing it indicates deactivation.

[0036] Meanwhile, in this embodiment of the invention, the disconnector operation interlocking unit is further used to connect the normally open node of the low pressure signal of the disconnector air chamber in series in the disconnector control circuit. When the pressure of the disconnector air chamber is low, the disconnector control circuit is disconnected to prevent the disconnector from being operated; at the same time, the switching circuit where the disconnector is located is cut off to prevent the automatic switching device from switching automatically.

[0037] like Figure 8 The diagram shows the main flow of an embodiment of an automatic switching method for main transformer protection trip output provided by the present invention. In this embodiment, it adopts the method described above. Figures 3 to 6 The system described is implemented, and the apparatus includes the following: Step S10: Collect the bus disconnector position signal of the current high-voltage side switch of the main transformer; It is understandable that the first trip output pressure plate in the first trip control unit and the second trip output pressure plate in the second trip control unit are put into operation once in the initial stage and remain in operation.

[0038] Step S11: Based on the busbar disconnector position signal, the corresponding switching relay in the trip control unit is automatically switched on and off, thereby realizing the automatic activation and deactivation of the corresponding trip pressure plate; thus only the trip circuit matching the currently operating busbar is activated, and non-associated circuits are disconnected. Specifically, in this step: When the busbar disconnector (1G) of the 1M busbar is closed and the busbar disconnector (2G) of the 2M busbar is open, the first switching relay (ZJ4) is energized, and its normally open contact closes, making the first sectionalizing switch tripping circuit conduct. At this time, when the air chamber pressure of the 2M busbar disconnector is low, the normally open contact 2GY1 of the 2M busbar disconnector air chamber pressure opens, cutting off the 2M busbar disconnector control circuit and prohibiting the 2M busbar disconnector from closing. At the same time, the normally open contact 2GY1 of the 2M busbar disconnector cuts off the switching circuit where the 2M busbar disconnector is located, preventing the second sectionalizing switch tripping circuit from conducting. When the busbar disconnector (2G) of the 2M busbar is closed and the busbar disconnector (1G) of the 1M busbar is open, the second switching relay (ZJ9) is energized, and its normally open contact closes, making the second sectional switch tripping circuit conduct. At this time, when the air chamber pressure of the 1M busbar disconnector is low, the normally open contact 1GY1 of the 1M busbar disconnector air chamber pressure is opened, cutting off the 1M busbar disconnector control circuit and prohibiting the 1M busbar disconnector from closing. At the same time, the normally open contact 1GY1 of the 1M busbar disconnector cuts off the switching circuit where the 1M busbar disconnector is located, preventing the first sectional switch tripping circuit from conducting.

[0039] Step S12: Control the indicator lights to turn on and off according to the switching relays in each trip control unit, so as to display the activation / deactivation status of the corresponding trip output pressure plate in real time.

[0040] Specifically, in this step, the LED indicator circuit of the status indicator unit is turned on or off according to the status of the corresponding switching relay. When the pressure plate of the trip circuit is turned on, the corresponding LED indicator lights up; otherwise, it turns off.

[0041] For more details, please refer to the aforementioned [reference]. Figures 3 to 7 The description of that will not be repeated here.

[0042] Implementing the embodiments of the present invention has the following beneficial effects: This invention provides an automatic switching device and method for the trip output of a main transformer protection system. By automatically detecting the open / close position signal of the busbar disconnector, the system automatically switches the trip output pressure plate on and off according to the open / close position of the busbar disconnector. The system also provides real-time indicator lights to remind on-site personnel of the current status of the pressure plate. This eliminates the need for manual switching of the pressure plate, thereby improving the safety and operation and maintenance efficiency of the power system.

[0043] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0044] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An automatic switching device for the tripping output of a main transformer protection system, applied to a 220kV double-busbar, double-section busbar structure, characterized in that... include: The disconnector position detection unit is used to collect the bus disconnector position signal of the current high-voltage side switch of the main transformer; Multiple trip control units are connected to each section switch. Each trip control unit includes a switching relay that is linked to its corresponding bus disconnect switch. The switching relay is connected in series to the trip circuit of its corresponding section switch. The switching relay is automatically controlled to open and close according to the bus disconnect switch position signal, thereby realizing the automatic activation and deactivation of the corresponding trip pressure plate. The status indicator unit is used to control the indicator lights to turn on and off according to the on and off states of the switching relays in each trip control unit, so as to display the on / off status of the corresponding trip output pressure plate in real time. The knife switch operation interlocking unit is used to lock the knife switch operation when a low air pressure alarm is triggered in the knife switch air chamber.

2. The apparatus as claimed in claim 1, characterized in that, The plurality of trip control units include: The first trip control unit includes a first sectionalizing switch trip circuit, which includes a pre-activated trip output first pressure plate; a first switching relay (ZJ4) is connected in series in the first sectionalizing switch trip circuit, and the first switching relay is controlled by the bus disconnector (1G) state of the 1M bus. The second trip control unit includes a second sectionalizing switch trip circuit, which includes a pre-activated trip output second pressure plate; a second switching relay (ZJ9) is connected in series in the second sectionalizing switch trip circuit, and the second switching relay is controlled by the bus disconnector (2G) state of the 2M bus.

3. The apparatus as described in claim 2, characterized in that, in: When the busbar disconnector (1G) of the 1M busbar is closed, the first switching relay (ZJ4) is energized, its normally open contact closes, which connects the first sectionalizing switch tripping circuit and disconnects the busbar disconnector (2G) of the 2M busbar; when the busbar disconnector (2G) of the 2M busbar is closed, the second switching relay (ZJ9) is energized, its normally open contact closes, which connects the second sectionalizing switch tripping circuit and disconnects the busbar disconnector (1G) of the 1M busbar.

4. The apparatus as described in claim 3, characterized in that, The status indication unit includes: The low-voltage power supply is isolated from the high-voltage tripping circuit; The LED indicator light, the current-limiting resistor, and the trip output pressure plate form a series circuit; The LED indicator circuit is controlled to be on or off according to the status of the corresponding switching relay. When the trip circuit is on, the corresponding LED indicator lights up; otherwise, it turns off.

5. The apparatus as described in claim 4, characterized in that, The indicator light is a high-brightness LED; when the light is on, it indicates that the pressure plate is engaged, and when the light is off, it indicates that the pressure plate is disengaged.

6. The apparatus as described in claim 5, characterized in that, The disconnector operation interlocking unit is further used to connect the normally open node of the low pressure signal of the disconnector air chamber in series in the disconnector control circuit. When the pressure of the disconnector air chamber is low, the disconnector control circuit is disconnected to prevent the disconnector from being operated; at the same time, the switching circuit where the disconnector is located is cut off to prevent the automatic switching device from switching automatically.

7. A method for automatic switching of main transformer protection trip outputs, implemented using the system described in any one of claims 1 to 6, characterized in that, Includes the following steps: Collect the position signal of the bus disconnect switch currently connected to the high-voltage side switch of the main transformer; The system automatically controls the switching relays in the trip control unit to open and close based on the busbar disconnector position signal, thereby enabling the automatic activation and deactivation of the corresponding trip pressure plate; thus, only the trip circuit matching the currently operating busbar is activated, while non-associated circuits are disconnected. The switching relays in each trip control unit are switched on and off, and the indicator lights are turned on and off to display the activation / deactivation status of the corresponding trip output pressure plate in real time.

8. The method as described in claim 7, characterized in that, Further includes: The first trip output pressure plate in the first trip control unit and the second trip output pressure plate in the second trip control unit are put into operation once in the initial stage and kept in constant operation.

9. The method as described in claim 8, characterized in that, The system automatically controls the switching relays in the trip control unit to open and close based on the busbar disconnector position signal, thereby automatically engaging and disengaging the corresponding tripping switch, further including: When the busbar disconnector (1G) of the 1M busbar is closed and the busbar disconnector (2G) of the 2M busbar is open, the first switching relay (ZJ4) is energized, and its normally open contact closes, making the first sectionalizing switch tripping circuit conduct. At this time, when the air chamber pressure of the 2M busbar disconnector is low, the normally open contact 2GY1 of the 2M busbar disconnector air chamber pressure opens, cutting off the 2M busbar disconnector control circuit and prohibiting the 2M busbar disconnector from closing. At the same time, the normally open contact 2GY1 of the 2M busbar disconnector cuts off the switching circuit where the 2M busbar disconnector is located, preventing the second sectionalizing switch tripping circuit from conducting. When the busbar disconnector (2G) of the 2M busbar is closed and the busbar disconnector (1G) of the 1M busbar is open, the second switching relay (ZJ9) is energized, and its normally open contact closes, making the second sectional switch tripping circuit conduct. At this time, when the air chamber pressure of the 1M busbar disconnector is low, the normally open contact 1GY1 of the 1M busbar disconnector air chamber pressure is opened, cutting off the 1M busbar disconnector control circuit and prohibiting the 1M busbar disconnector from closing. At the same time, the normally open contact 1GY1 of the 1M busbar disconnector cuts off the switching circuit where the 1M busbar disconnector is located, preventing the first sectional switch tripping circuit from conducting.

10. The method as described in claim 9, characterized in that, Based on the on / off state of the switching relays in each trip control unit, the indicator lights are controlled to turn on and off, so as to display the real-time on / off status of the corresponding trip output pressure plate, further including: The status indicator unit controls the on / off state of the corresponding LED indicator circuit according to the status of the switching relay. When the trip circuit pressure plate is engaged, the corresponding LED indicator lights up; otherwise, it turns off.

Images