A control circuit for synchronous switching-on and switching-off of DC isolation devices of multiple transformers

Abstract

The present invention discloses a control circuit for synchronous switching-on and switching-off of multiple transformer DC isolation devices, comprising: N DC isolation devices, where N > 2, and the DC isolation devices are cascaded with each other. The DC isolation device includes: a controller, a linkage switching-on control branch, and a transformer connection branch. The first port of the controller is connected to the input end of the linkage switching-on control branch and sends a linkage switching-on control signal. Its second port is connected to the first output end of the linkage switching-on control branch and obtains a linkage switching-on execution signal. Its third port is connected to the second output end of the linkage switching-on control branch to provide a power supply signal to the linkage switching-on control branches of other DC isolation devices. The controller is connected to the switching switch on the transformer connection branch and controls the switching switch to close according to the linkage switching-on execution signal, so as to realize the synchronous switching-on of N DC isolation devices. It avoids the damage caused by the additional DC bias borne by other transformers due to asynchronous switching-on and switching-off, and prolongs the service life.

Description

Technical Field

[0001] The present invention relates to the fields of power plants and substations, and in particular to a control circuit for synchronous switching-on and switching-off of multiple transformer DC isolation devices. Background Art

[0002] In recent years, with the rapid development of the power grid, the AC-DC hybrid power transmission mode of DC power transmission and AC power transmission has become more and more common. In this process, the single-pole grounding operation of the DC transmission line causes part of the DC current to flow into the AC substation system, which has an adverse effect on the neutral point of the transformer, and then leads to DC bias, magnetic saturation and harmonic increase of the transformer, affecting the safe and stable operation of the transformer and the AC system. In addition, continuous noise and vibration also have a negative impact on the daily life of surrounding residents.

[0003] To alleviate this problem, the PAC-50K DC isolation device isolates the DC component by connecting a capacitor to the neutral point of the transformer, thereby blocking the influence of the DC current on the transformer. However, when multiple transformer systems operate in parallel, since each DC isolation device works independently, synchronous switching-on or synchronous switching-off cannot be achieved, resulting in problems such as increased DC bias in the case of non-synchronization. Especially when a single device fails or is under maintenance, the load of other devices is increased, thus affecting the safety and stability of the system. Summary of the Invention

[0004] An embodiment of the present invention provides a control circuit for synchronous switching-on and switching-off of multiple transformer DC isolation devices to solve the problem of increased DC bias caused by the inability of each DC isolation device to achieve synchronous switching-on or synchronous switching-off.

[0005] Based on the above object, in one embodiment, a control circuit for synchronous switching-on and switching-off of multiple transformer DC isolation devices is provided, including: N DC isolation devices, where N>2, and the DC isolation devices are cascaded with each other. Each of the DC isolation devices includes: a controller, a linkage switching-on control branch, and a transformer connection branch;

[0006] The first port of the controller is connected to the input end of the linkage switching-on control branch for sending a linkage switching-on control signal to the linkage switching-on control branch. The second port of the controller is connected to the first output end of the linkage switching-on control branch for obtaining a linkage switching-on execution signal. The third port of the controller is connected to the second output end of the linkage switching-on control branch for providing a power supply signal to the linkage switching-on control branch of other DC isolation devices through the second output end of the linkage switching-on control branch;

[0007] The controller is connected to a switching switch on the transformer connection branch to control the switching switch on the transformer connection branch to close according to the linkage switching-on execution signal, so as to realize the synchronous switching-on of the N DC isolation devices.

[0008] In one embodiment, each of the DC-blocking devices further includes: a global input status monitoring branch. The input end of the global input status monitoring branch is connected to the fourth port of the controller, and is used to obtain the DC-blocking input status monitoring signal output by the controller. The first output end of the global input status monitoring branch is connected to the fifth port of the controller, and is used to output the global input status monitoring signal to the controller. The second output ends of the global input status monitoring branches of each of the DC-blocking devices are connected to form a DC-blocking input status loop.

[0009] In one embodiment, the global input status monitoring branch includes: a DC-blocking input status switch and a global input status switch. The control end of the DC-blocking input status switch serves as the input end of the global input status monitoring branch. Both ends of the DC-blocking input status switch serve as the second output end of the global input status monitoring branch. The input end of the global input status switch is connected to the output end of the DC-blocking input status switch. The output end of the global input status switch serves as the first output end of the global input status monitoring branch.

[0010] In one embodiment, it further includes: a control host, which is respectively connected to the sixth ports of the controllers of each of the DC-blocking devices, and is used to obtain the global input status monitoring signals sent by each of the controllers, and determine whether the N DC-blocking devices are synchronously input according to the N global input status monitoring signals.

[0011] In one embodiment, the DC-blocking device further includes: a camera module. The input end of the camera module is used to obtain a first switch image containing the changeover switch on the transformer connection branch and a second switch image containing the DC-blocking input status switch of the global input status monitoring branch.

[0012] The output end of the camera module is connected to the seventh port of the controller, and is used to input the first switch image and the second switch image into the trained switch status monitoring model, output the input status of the changeover switch and the input status of the DC-blocking input status switch to the controller, and send the input status of the changeover switch and the input status of the DC-blocking input status switch to the control host through the sixth port of the controller.

[0013] The control host is used to determine whether each of the DC-blocking devices is synchronously input according to the input status of the N changeover switches, and determine whether the controller has a communication failure according to the input status of the N DC-blocking input status switches.

[0014] In one embodiment, a control circuit for synchronous switching-on and switching-off of multiple transformer DC-blocking devices is provided, including: N DC-blocking devices, where N > 2, and the DC-blocking devices are cascaded with each other. Each of the DC-blocking devices includes: a controller, a linkage-off control branch, and a transformer connection branch;

[0015] The eighth port of the controller is connected to the input end of the linkage-off control branch, and is used to send a linkage-off control signal to the linkage-off control branch. The ninth port of the controller is connected to the first output end of the linkage-off control branch, and is used to obtain a linkage-off execution signal. The second output ends of the linkage-off control branches of the DC-blocking devices are connected to form a DC-blocking-off loop;

[0016] The controller is connected to the switching switch on the transformer connection branch, and is used to control the switching switch on the transformer connection branch to disconnect according to the linkage-off execution signal, so as to realize the synchronous switching-off of the N DC-blocking devices.

[0017] In one embodiment, each of the DC-blocking devices further includes: a global-off state monitoring branch. The input end of the global-off state monitoring branch is connected to the tenth port of the controller, and is used to obtain a DC-blocking-off state monitoring signal output by the controller. The first output end of the global-off state monitoring branch is connected to the eleventh port of the controller, and is used to output a global-off state monitoring signal to the controller. The twelfth port of the controller is connected to the second output end of the global-off state monitoring branch, and is used to obtain the global-off state monitoring signals of other DC-blocking devices through the second output end of the global-off state monitoring branch.

[0018] In one embodiment, the global-off state monitoring branch includes: a DC-blocking-off state switch and a global-off state switch. The control end of the DC-blocking-off state switch is used as the input end of the global-off state monitoring branch. One end of the DC-blocking-off state switch is connected to the power supply of the DC-blocking device. The other end of the DC-blocking-off state switch is used as the second output end of the global-off state monitoring branch. The other end of the DC-blocking-off state switch is further connected to the input end of the global-off state switch. The output end of the global-off state switch is used as the first output end of the global-off state monitoring branch.

[0019] In one embodiment, it further includes: a control host, which is respectively connected to the sixth ports of the controllers of the DC-blocking devices, and is used to obtain the global-off state monitoring signals sent by the controllers, and determine whether the N DC-blocking devices are synchronously switched off according to the N global-off state monitoring signals.

[0020] In one embodiment, the DC-blocking device further includes: a camera module, an input end of the camera module is configured to obtain a first switch image containing a switching switch on a transformer connection branch and a second switch image containing a DC-blocking exit status switch of a global exit status monitoring branch;

[0021] An output end of the camera module is connected to a seventh port of the controller, and is configured to input the first switch image and the second switch image into a trained switch status monitoring model, output an exit status of the switching switch and an exit status of the DC-blocking exit status switch to the controller, and send the exit status of the switching switch and the exit status of the DC-blocking exit status switch to the control host through a sixth port of the controller;

[0022] The control host is configured to determine whether each DC-blocking device exits synchronously according to the exit statuses of N switching switches, and determine whether the controller has a communication failure according to the exit statuses of N DC-blocking exit status switches.

[0023] The above control circuit for synchronous switching-on and switching-off of multiple transformer DC-blocking devices cascades each DC-blocking device, enabling communication between the controllers of each DC-blocking device. It controls each DC-blocking device through a linkage switching-on control branch to achieve synchronous switching-on operation, suppress the influence of DC current on the transformer, avoid transformer failures caused by DC bias, and ensure the safe and stable operation of the transformer. It controls each DC-blocking device through a linkage switching-off control branch to achieve synchronous switching-off actions, avoid additional DC bias current borne by other transformers due to asynchronous switching-off, thereby avoiding damage to the transformer and extending the service life of the equipment. Description of the Drawings

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings without creative efforts.

[0025] Figure 1 is a circuit diagram of linkage switching-on control in an embodiment of the present invention;

[0026] Figure 2 is a signal diagram of all 1SK switches when any one DC-blocking device meets the switching-on conditions in an embodiment of the present invention;

[0027] Figure 3 is a signal diagram of all 1SK switches when one DC-blocking device is in an abnormal state in an embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the voltage change across the capacitor of the DC-blocking device when one DC-blocking device enters the bypass protection state in an abnormal state in an embodiment of the present invention;

[0029] Figure 5 It is a circuit diagram of the linkage input control and linkage input monitoring in an embodiment of the present invention;

[0030] Figure 6 It is a circuit diagram of the linkage exit control in an embodiment of the present invention;

[0031] Figure 7 It is a signal schematic diagram of all 1SK switches when all DC-blocking devices meet the exit conditions in an embodiment of the present invention;

[0032] Figure 8 It is a signal schematic diagram of all 1SK switches when one DC-blocking device does not meet the exit conditions or is in an abnormal state in an embodiment of the present invention;

[0033] Figure 9 It is a circuit diagram of the linkage exit control and linkage exit monitoring in an embodiment of the present invention.

[0034] Reference numerals: 1, controller; 101, the first port of the controller; 102, the second port of the controller; 103, the third port of the controller; 104, the fourth port of the controller; 105, the fifth port of the controller; 106, the sixth port of the controller; 108, the eighth port of the controller; 109, the ninth port of the controller; 110, the tenth port of the controller; 111, the eleventh port of the controller; 112, the twelfth port of the controller; 3, linkage input control branch; 5, control host; 7, global input status monitoring branch; 9, linkage exit control branch; 11, global exit status monitoring branch. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0036] It should be understood that the present invention can be implemented in different forms and should not be construed as limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. In the drawings, for clarity, the dimensions and relative dimensions of layers and regions may be exaggerated. The same reference numerals denote the same elements throughout.

[0037] It should be understood that when an element or layer is referred to as being "on", "adjacent to", "connected to" or "coupled to" another element or layer, it can be directly on, adjacent to, connected or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on", "directly adjacent to", "directly connected to" or "directly coupled to" another element or layer, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers and / or portions, these elements, components, regions, layers and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or portion from another element, component, region, layer or portion. Thus, without departing from the teachings of the present invention, the first element, component, region, layer or portion discussed below may be denoted as the second element, component, region, layer or portion.

[0038] Spatial relationship terms such as "under", "below", "lower", "beneath", "above", "upper", etc. are used herein for convenience in describing the relationship of one element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientation shown in the figures, spatial relationship terms are intended to also include different orientations of the device in use and operation. For example, if the device in the figures is flipped, then an element or feature described as "under" or "beneath" or "below" another element or feature will be oriented "above" the other element or feature. Thus, the exemplary terms "under" and "beneath" can include both an upper and a lower orientation. The device may be otherwise oriented (rotated 90 degrees or other orientations) and the spatial descriptors used herein are to be interpreted accordingly.

[0039] The purpose of the terms used herein is only to describe specific embodiments and is not a limitation of the present invention. As used herein, the singular forms "a", "an" and "the" are also intended to include the plural forms unless the context clearly dictates otherwise. It should also be understood that the terms "comprising" and / or "including", when used in this specification, specify the presence of the stated features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0040] To fully understand the present invention, detailed structures and steps will be set forth in the following description in order to explain the technical solutions proposed by the present invention. The preferred embodiments of the present invention are described in detail below. However, in addition to these detailed descriptions, the present invention may have other embodiments.

[0041] In one embodiment, a control circuit for synchronously switching on and off multiple DC isolation devices for transformers is provided, as Figure 1 shown, including: N DC isolation devices, where N > 2, and the DC isolation devices are cascaded with each other. Each of the DC isolation devices includes: a controller 1, a linkage input control branch 3, and a transformer connection branch;

[0042] The first port 101 of the controller is connected to the input end of the linkage input control branch 3 for sending a linkage input control signal to the linkage input control branch 3. The second port 102 of the controller is connected to the first output end of the linkage input control branch 3 for obtaining a linkage input execution signal. The third port 103 of the controller is connected to the second output end of the linkage input control branch 3 for providing a power signal to the linkage input control branches of other DC isolation devices through the second output end of the linkage input control branch 3;

[0043] The controller 1 is connected to the switching switch on the transformer connection branch to control the closing of the switching switch on the transformer connection branch according to the linkage input execution signal, so as to realize the synchronous input of the N DC isolation devices.

[0044] Among them, as Figure 1 shown, the linkage input control branch 3 is specifically provided with a linkage input control output switch, a linkage input execution input switch, and a power supply. One end of the linkage input control output switch is connected to the power supply, and the other end is connected to the linkage input execution input switch. Among them, the linkage input control output switch is a relay switch, and the linkage input execution input switch is an optocoupler.

[0045] The working process of the above control circuit is as follows:

[0046] When the controller 1 of any one of the N DC isolation devices detects that the DC current at the neutral point of the transformer connected to it is greater than or equal to 50 A, that is, when the input condition is met, the first port 101 of the controller sends a linkage input control signal to the linkage input control branch 3, causing the linkage input control output switch of the linkage input control branch 3 to close, outputting a power signal to the linkage input execution input switch to make it close. The second port 102 of the controller obtains the linkage input execution signal output from the first output end of the linkage input control branch 3 and makes the switching switch on the transformer connection branch close, so that the DC isolation device enters the input state;

[0047] While outputting a power signal to the linkage input execution input switch to make it close, as Figure 2As shown, at this time, let N = 3. The switch 1SK is a linkage input execution input switch. The second output terminal of the linkage input control branch of branch 3 also outputs a power signal to the linkage input control branches of other DC-blocking devices, causing the linkage input execution input switches of other DC-blocking devices to close, that is, the signal of switch 1SK is 1, and the switching switches on the transformer connection branches of other DC-blocking devices are also closed, so that other DC-blocking devices also enter the input state synchronously, thus realizing the synchronous input of N DC-blocking devices.

[0048] As Figure 3 shown, at this time, let N = 3. The switch 1SK is a linkage input execution input switch. When one DC-blocking device is in an abnormal state, such as severe DC bias abnormality exceeding the load of the DC-blocking device, even if the other two DC-blocking devices meet the input conditions, the linkage input execution input switch of the abnormal DC-blocking device remains open, and all DC-blocking devices do not enter the input state;

[0049] As Figure 4 shown, at this time, the system enters the bypass protection state, quickly releases the voltage across the DC-blocking capacitor, enables the DC-blocking device to return to the normal state, and starts to be used again.

[0050] In this embodiment, by cascading and connecting between the DC-blocking devices, the controllers of the DC-blocking devices can communicate with each other. The linkage input control branch is used to control each DC-blocking device to realize synchronous input operation, suppress the influence of DC current on the transformer, avoid the transformer from malfunctioning due to DC bias, and ensure the safe and stable operation of the transformer.

[0051] In one embodiment, as Figure 5 shown, each of the DC-blocking devices further includes: a global input state monitoring branch 7. The input end of the global input state monitoring branch 7 is connected to the fourth port 104 of the controller, and is used to obtain the DC-blocking input state monitoring signal output by the controller 1. The first output end of the global input state monitoring branch 7 is connected to the fifth port 105 of the controller, and is used to output the global input state monitoring signal to the controller 1. The second output ends of the global input state monitoring branches 7 of each of the DC-blocking devices are connected to form a DC-blocking input state loop.

[0052] Among them, the working process of the above control circuit is as follows:

[0053] When the controller 1 of any one of the N DC-blocking devices detects that the DC current at the neutral point of the transformer connected thereto is greater than or equal to 50 A, that is, when the input condition is met, the first port 101 of the controller sends a linkage input control signal to the linkage input control branch 3, causing the linkage input control switch of the linkage input control branch 3 to close, outputting a power signal to the linkage input execution switch to make it close. The second port 102 of the controller obtains the linkage input execution signal output from the first output end of the linkage input control branch 3, and closes the changeover switch on the transformer connection branch, so that the DC-blocking device enters the input state;

[0054] While outputting the power signal to the linkage input execution switch to make it close, the second output end of the linkage input control branch 3 also outputs a power signal to the linkage input control branches of other DC-blocking devices, causing the linkage input execution switches of other DC-blocking devices to close, and also closing the changeover switches on the transformer connection branches of other DC-blocking devices, so that other DC-blocking devices also enter the input state synchronously;

[0055] After the controller 1 of the DC-blocking device detects that the DC-blocking device enters the input state, the fourth port 104 of the controller outputs a DC-blocking input state monitoring signal to the input end of the global input state monitoring branch 7. The second output ends of each global input state monitoring branch 7 are connected to form a DC-blocking input state loop, and then through the first output end of the global input state monitoring branch 7, output a global input state monitoring signal to the fifth port 105 of the controller, realizing the synchronous input of N DC-blocking devices.

[0056] In this embodiment, by setting up the global input state monitoring branch, the global input state monitoring signals of each DC-blocking device are transmitted to the controllers of each DC-blocking device, and the operating states of each DC-blocking device are monitored in real time, realizing unified monitoring and management of the DC-blocking input states of the entire system, enabling the controllers of each DC-blocking device to communicate with each other, controlling each DC-blocking device through the linkage input control branch to achieve synchronous input operation, suppressing the influence of DC current on the transformer, avoiding faults of the transformer due to DC bias, and ensuring the safe and stable operation of the transformer.

[0057] In one embodiment, as Figure 5 shown, the global input state monitoring branch 7 includes: a DC-blocking input state switch and a global input state switch. The control end of the DC-blocking input state switch serves as the input end of the global input state monitoring branch 7, the two ends of the DC-blocking input state switch serve as the second output ends of the global input state monitoring branch 7, the input end of the global input state switch is connected to the output end of the DC-blocking input state switch, and the output end of the global input state switch serves as the first output end of the global input state monitoring branch 7.

[0058] Among them, as Figure 5 shown, the control terminal of the DC-blocking input state switch is connected to the fourth port 104 of the controller and serves as the input end of the global input state monitoring branch 7, receiving the DC-blocking input state monitoring signal output by the controller 1. The two ends of the DC-blocking input state switch serve as the second output end of the global input state monitoring branch 7 and are connected to the DC-blocking input state switches of the global input state monitoring branches of other DC-blocking devices to form a DC-blocking input state loop. The output end of the DC-blocking input state switch is also connected to the input end of the global input state switch, used to receive the global input state monitoring signal of the DC-blocking input state loop and output it to the fifth port 105 of the controller. Among them, the DC-blocking input state switch is a relay switch, and the global input state switch is an optocoupler.

[0059] The working process of the above control circuit is as follows:

[0060] When the controller 1 of any one of the N DC-blocking devices detects that the DC current at the neutral point of the transformer connected to it is greater than or equal to 50 A, that is, when the input condition is met, the first port 101 of the controller sends a linkage input control signal to the linkage input control branch 3, causing the linkage input control output switch of the linkage input control branch 3 to close, outputting a power signal to the linkage input execution input switch to make it close. The second port 102 of the controller obtains the linkage input execution signal output from the first output end of the linkage input control branch 3 and makes the changeover switch on the transformer connection branch close, so that the DC-blocking device enters the input state;

[0061] While outputting the power signal to the linkage input execution input switch to make it close, the second output end of the linkage input control branch 3 also outputs a power signal to the linkage input control branches of other DC-blocking devices, making the linkage input execution input switches of other DC-blocking devices close, and making the changeover switches on the transformer connection branches of other DC-blocking devices also close, so that other DC-blocking devices also enter the input state synchronously;

[0062] After the controller 1 of the DC-blocking device detects that the DC-blocking device enters the input state, the fourth port 104 of the controller outputs a DC-blocking input state monitoring signal to the DC-blocking input state switch of the global input state monitoring branch 7 and makes the DC-blocking input state switch close. When all the DC-blocking input state switches in all DC-blocking devices are closed, a DC-blocking input state loop is formed. The DC-blocking input state monitoring signal is transmitted through the DC-blocking input state loop to the global state switches of each global input state monitoring branch 7 and makes them close. At this time, the global input state monitoring signal is 1, and then the global input state monitoring signal is transmitted to the controller 1 through the fifth port 105 of the controller to realize the synchronous input of N DC-blocking devices;

[0063] When a certain one of the N DC-blocking devices fails and cannot enter the energized state synchronously with other DC-blocking devices, the DC-blocking input state switch of this device is in the off state. At this time, the DC-blocking input state loop cannot form a path, and the DC-blocking input state monitoring signal cannot be transmitted through the DC-blocking input state loop. The global state switch of the global input state monitoring branch 7 is also turned off. At this time, the global input state monitoring signal is 0, and the global input state monitoring signal is transmitted to the controller 1 through the fifth port 105 of the controller.

[0064] In this embodiment, by setting a DC-blocking input state switch in the global input state monitoring branch and connecting the DC-blocking input state switches in each DC-blocking device in series to form a DC-blocking input state loop, it is ensured that only when all DC-blocking devices enter the energized state synchronously can the global state switch of the global input state monitoring branch receive the signal and transmit it to the controllers of each DC-blocking device, realizing the unity of the DC-blocking input state of the entire system, ensuring that each DC-blocking device enters the synchronous operation, suppressing the influence of the DC current on the transformer, avoiding the failure of the transformer due to DC bias, and ensuring the safe and stable operation of the transformer.

[0065] In one embodiment, as Figure 5 described, it further includes: a control host 5, which is respectively connected to the sixth port 106 of the controllers of each DC-blocking device, and is used to obtain the global input state monitoring signals sent by each controller, and determine whether the N DC-blocking devices are synchronously energized according to the N global input state monitoring signals.

[0066] Among them, the working process of the above control circuit is as follows:

[0067] When the controller of any one of the N DC-blocking devices detects that the DC current at the neutral point of the transformer connected to it is greater than or equal to 50A, that is, when the input condition is met, the first port 101 of the controller sends a linkage input control signal to the linkage input control branch 3, causing the linkage input control output switch of the linkage input control branch 3 to close, outputting a power signal to the linkage input execution input switch to make it close. The second port 102 of the controller obtains the linkage input execution signal output from the first output end of the linkage input control branch 3, and closes the switch on the transformer connection branch, so that the DC-blocking device enters the energized state;

[0068] While outputting the power signal to the linkage input execution input switch to make it close, the second output end of the linkage input control branch 3 also outputs a power signal to the linkage input control branches of other DC-blocking devices, causing the linkage input execution input switches of other DC-blocking devices to close, and causing the switches on the transformer connection branches of other DC-blocking devices to also close, so that other DC-blocking devices also enter the energized state synchronously;

[0069] When the controller 1 of the DC-blocking device detects that the DC-blocking device enters the input state, the fourth port 104 of the controller outputs a DC-blocking input state monitoring signal to the DC-blocking input state switch of the global input state monitoring branch 7, and closes the DC-blocking input state switch. When all the DC-blocking input state switches in all the DC-blocking devices are closed, a DC-blocking input state loop is formed. The DC-blocking input state monitoring signal is transmitted through the DC-blocking input state loop to the global state switches of each global input state monitoring branch and closes them. Finally, the global input state monitoring signal is transmitted to the controller 1 through the fifth port 105 of the controller. The controller 1 outputs the received global input state monitoring signal to the control host 5 through the sixth port 106 of the controller. The control host 5 determines whether the N DC-blocking devices are synchronously input according to the received N global input state monitoring signals. If the received global input state monitoring signal is 1, the synchronous input of the N DC-blocking devices is realized;

[0070] When a certain one of the N DC-blocking devices fails and cannot enter the input state synchronously with other DC-blocking devices, its DC-blocking input state switch is in the off state. At this time, the DC-blocking input state loop cannot form a path, and the DC-blocking input state monitoring signal cannot be transmitted through the DC-blocking input state loop. The global state switch of the global input state monitoring branch 7 is also off. At this time, the global input state monitoring signal is 0. The global input state monitoring signal is transmitted to the controller 1 through the fifth port 105 of the controller. The controller 1 outputs the received global input state monitoring signal to the control host 5 through the sixth port 106 of the controller. At the same time, the controller 1 also outputs an alarm signal to the control host 5. Since the synchronous input is not realized, the control host 5 sends signals to each controller to make the DC-blocking devices that have entered the input state exit the input. The control host 5 determines the position of the faulty DC-blocking device according to the received alarm signal and withdraws the faulty DC-blocking device from the system for maintenance. After the faulty device exits the system, it will not affect the normal operation of other DC-blocking devices in the system.

[0071] In this embodiment, the control host is connected to the sixth port of the controller of each DC-blocking device to obtain the global input state monitoring signal, and determines whether the N DC-blocking devices are synchronously input according to the global input state monitoring signal, centrally manages and monitors the working states of each DC-blocking device, discovers and repairs in time when a fault occurs, ensures that each DC-blocking device realizes synchronous input operation, suppresses the influence of the DC current on the transformer, avoids the transformer from failing due to DC bias, reduces the damage of the equipment, and improves the service life of the equipment.

[0072] In one embodiment, the DC-blocking device further includes: a camera module, an input end of the camera module is configured to obtain a first switch image containing a change-over switch on the transformer connection branch and a second switch image containing a DC-blocking input status switch of the global input status monitoring branch;

[0073] An output end of the camera module is connected to a seventh port of the controller, and is configured to input the first switch image and the second switch image into a trained switch status monitoring model, output the input status of the change-over switch and the input status of the DC-blocking input status switch to the controller 1, and send the input status of the change-over switch and the input status of the DC-blocking input status switch to the control host 5 through a sixth port 106 of the controller;

[0074] The control host 5 is configured to determine whether the DC-blocking devices are synchronously input according to the input statuses of N change-over switches, and determine whether the controller 1 has a communication failure according to the input statuses of N DC-blocking input status switches.

[0075] Wherein, the camera module is used to obtain the first switch image and the second switch image, and output the real-time captured first switch image and second switch image to the switch status monitoring model. The switch status monitoring model adopts a neural network with an encoder and a decoder structure. The trained switch status monitoring model can be used to predict the input status of the change-over switch and the input status of the DC-blocking input status switch. The training process of the switch status monitoring model is: input the first switch image sample and the second switch image sample with input status labels into the switch status monitoring model under initial parameters, use the cross-loss entropy function to calculate the deviation between the prediction result of the switch status monitoring model and the input status label. When the deviation reaches a preset condition, stop the model training, update the model parameters, and obtain the trained switch status monitoring model. The switch status monitoring model can implement the prediction of the input status of the switch through a separately provided processor, or can be implemented through the controller 1.

[0076] The switch status monitoring model obtains the input status of the change-over switch and the input status of the DC-blocking input status switch according to the first switch image and the second switch image, and outputs them to the controller 1, and then outputs them to the control host 5 through the controller 1 to determine whether there is a communication failure.

[0077] The working process of the above control circuit is as follows:

[0078] When the controller of any one of the N DC-blocking devices detects that the DC current at the neutral point of the transformer connected thereto is greater than or equal to 50 A, that is, when the input condition is met, the first port 101 of the controller sends a linkage input control signal to the linkage input control branch 3, causing the linkage input control switch of the linkage input control branch 3 to close, outputting a power signal to the linkage input execution switch to make it close. The second port 102 of the controller obtains the linkage input execution signal output from the first output end of the linkage input control branch 3, and closes the switch on the transformer connection branch of the DC-blocking device, so that the DC-blocking device enters the input state;

[0079] When outputting the power signal to the linkage input execution switch to make it close, the second output end of the linkage input control branch 3 also outputs a power signal to the linkage input control branches of other DC-blocking devices, causing the linkage input execution switches of other DC-blocking devices to close, and also closing the switches on the transformer connection branches of other DC-blocking devices, so that other DC-blocking devices also enter the input state synchronously;

[0080] After the controller 1 of the DC-blocking device detects that the DC-blocking device enters the input state, the fourth port 104 of the controller outputs a DC-blocking input state monitoring signal to the DC-blocking input state switch of the global input state monitoring branch 7, and makes the DC-blocking input state switch close. When all the DC-blocking input state switches in all the DC-blocking devices are closed, a DC-blocking input state loop is formed. The DC-blocking input state monitoring signal is transmitted through the DC-blocking input state loop to the global state switches of each global input state monitoring branch 7 and makes them close. Finally, the global input state monitoring signal is transmitted to the controller 1 through the fifth port 105 of the controller. The controller 1 outputs the received global input state monitoring signal to the control host 5 through the sixth port 106 of the controller. The control host 5 determines whether the N DC-blocking devices are synchronously input according to the received N global input state monitoring signals. If the received global input state monitoring signal is 1, the synchronous input of the N DC-blocking devices is achieved;

[0081] If a communication fault occurs when the fourth port 104 of the controller outputs a DC-blocking input status monitoring signal to the DC-blocking input status switch of the global input status monitoring branch 7, at this time, the DC-blocking input status loop cannot form a path, and the global input status monitoring signal is 0. However, if the control host 5 does not receive an alarm signal, the camera module acquires the first switch image of the changeover switch on the transformer connection branch and the second switch image of the DC-blocking input status switch of the global input status monitoring branch 7, and outputs them to the controller 1 through the seventh port of the controller. The controller 1 outputs the input status of the changeover switch and the input status of the DC-blocking input status switch to the control host 5 through the trained switch status monitoring model. The control host 5 makes a judgment. If the input status of the changeover switch is closed, but the input status of the DC-blocking input status switch is open, the control host 5 determines that a communication fault has occurred, but synchronous input has been achieved. At this time, only the faulty DC-blocking device is taken out of the system for maintenance, and the other already input DC-blocking devices remain in the input state.

[0082] In this embodiment, by setting the camera module to acquire the first switch image and the second switch image and output them to the controller, the input status of the changeover switch and the input status of the DC-blocking input status switch are obtained, and then the input status of the changeover switch and the input status of the DC-blocking input status switch are output to the monitoring host for judgment, avoiding misjudgment caused by communication faults, making the control circuit more perfect, ensuring that each DC-blocking device realizes synchronous input operation, suppressing the influence of DC current on the transformer, and avoiding faults of the transformer due to DC bias.

[0083] In one embodiment, as Figure 6 shown, a control circuit for synchronous input and output of multiple transformer DC-blocking devices is provided, including: N DC-blocking devices, where N > 2, and the DC-blocking devices are cascaded with each other. Each of the DC-blocking devices includes: a controller 1, a linkage withdrawal control branch 9, and a transformer connection branch;

[0084] The eighth port 108 of the controller is connected to the input end of the linkage withdrawal control branch 9 for sending a linkage withdrawal control signal to the linkage withdrawal control branch 9. The ninth port 109 of the controller is connected to the first output end of the linkage withdrawal control branch 9 for acquiring a linkage withdrawal execution signal. The second output ends of the linkage withdrawal control branches of the DC-blocking devices are connected to form a DC-blocking withdrawal loop;

[0085] The changeover switch on the transformer connection branch is also used to control the changeover switch on the transformer connection branch to disconnect according to the linkage withdrawal execution signal, so as to realize the synchronous withdrawal of the N DC-blocking devices.

[0086] Among them, as Figure 6As shown in the figure, the linkage withdrawal control branch 9 is specifically provided with a linkage withdrawal control output switch and a linkage withdrawal input switch. The controlled end of the linkage withdrawal control output switch is connected to the eighth port 108 of the controller. The second output end of the linkage withdrawal control branch 9, whose two ends are connected to other DC-blocking devices, forms a DC-blocking withdrawal loop. One end of the linkage withdrawal control output switch is also connected to the input end of the linkage withdrawal input switch, and the output end of the linkage withdrawal input switch is connected to the ninth port 109 of the controller. Among them, the linkage input control output switch is a relay switch, and the linkage input execution input switch is an optocoupler.

[0087] The working process of the above control circuit is as follows:

[0088] When the controller 1 of the DC-blocking device detects that the DC current at the neutral point of the transformer connected to it is less than 50 A, that is, when the withdrawal condition is met, the eighth port 108 of the controller sends a linkage withdrawal control signal to the linkage withdrawal control branch 9, causing the linkage withdrawal control output switch to close. When all DC-blocking devices meet the withdrawal conditions, the linkage withdrawal control branches 9 of all DC-blocking devices form a DC-blocking withdrawal loop, and transmit the linkage withdrawal control signal through the DC-blocking withdrawal loop to the input end of the linkage withdrawal input switch of the linkage withdrawal control branch 9 of each DC-blocking device. After receiving the linkage withdrawal control signal, the linkage withdrawal input switch closes. As Figure 7 shown in the figure, at this time, let N = 3, and the switch 1SK is the linkage withdrawal input switch, that is, the signal of the switch 1SK is 1. The linkage withdrawal execution signal is sent to the controller 1 through the ninth port 109 of the controller. The ninth port 109 of the controller obtains the linkage withdrawal execution signal output by the linkage withdrawal control branch 9, and disconnects the change-over switch on the transformer connection branch, so that the DC-blocking device enters the withdrawal state, realizing the synchronous withdrawal of N DC-blocking devices;

[0089] As Figure 8 shown in the figure, at this time, let N = 3, and the switch 1SK is the linkage withdrawal input switch. When one DC-blocking device does not meet the withdrawal conditions or is in an abnormal state, such as when the DC bias is extremely abnormal, the linkage withdrawal input switches of all DC-blocking devices remain open, and all DC-blocking devices remain in the input state and do not withdraw.

[0090] In this embodiment, the synchronous withdrawal operation of each DC-blocking device is controlled through the linkage withdrawal control branch, suppressing the influence of DC current on the transformer, avoiding the failure of the unwithdrawn transformer due to excessive DC bias, and at the same time avoiding the damage of the transformer caused by the large through-current borne by the transformer winding, ensuring the safe and stable operation of the transformer.

[0091] In one embodiment, as Figure 9As shown, each of the DC blocking devices further includes: a global exit status monitoring branch 11. The input end of the global exit status monitoring branch 11 is connected to the tenth port 110 of the controller, and is used to obtain the DC blocking exit status monitoring signal output by the controller 1. The first output end of the global exit status monitoring branch 11 is connected to the eleventh port 111 of the controller, and is used to output the global exit status monitoring signal to the controller 1. The twelfth port 112 of the controller is connected to the second output end of the global exit status monitoring branch 11, and is used to obtain the global exit status monitoring signals of other DC blocking devices through the second output end of the global exit status monitoring branch 11.

[0092] Among them, the working process of the above control circuit is as follows:

[0093] When the controller 1 of the DC blocking device detects that the DC current at the neutral point of the transformer connected thereto is less than 50 A, that is, when the exit condition is met, the eighth port 108 of the controller sends a linkage exit control signal to the linkage exit control branch 9 to close the linkage exit control opening switch. When all the DC blocking devices meet the exit conditions, the linkage exit control branches 9 of all the DC blocking devices form a DC blocking exit loop, and transmit the linkage exit control signal to the input end of the linkage exit opening switch of the linkage exit control branch 9 of each DC blocking device through the DC blocking exit loop. After receiving the linkage exit control signal, the linkage exit opening switch closes, and sends the linkage exit execution signal to the controller 1 through the ninth port 109 of the controller. The ninth port 109 of the controller obtains the linkage exit execution signal output by the linkage exit control branch 9, and disconnects the changeover switch on the transformer connection branch, so that the DC blocking device enters the exit state;

[0094] After all the controllers 1 of the DC blocking devices detect that the DC blocking devices enter the exit state, the tenth port 110 of the controller outputs a DC blocking exit status monitoring signal to the input end of the global exit status monitoring branch 11 to disconnect the power signal. After the signal power supplies of all the DC blocking devices are disconnected, the global exit status monitoring branch 11 obtains the global exit status monitoring signals of other DC blocking devices through its second output end. When the global exit status monitoring signals of all the DC blocking devices are 0, the first output end of the global exit status monitoring branch 11 outputs the global exit status monitoring signal to the controller 1 through the eleventh port 111 of the controller, realizing the synchronous exit of N DC blocking devices.

[0095] In this embodiment, by setting up a global exit status monitoring branch, the global exit status monitoring signals of each DC-blocking device are transmitted to the controller, realizing unified monitoring and management of the DC-blocking exit status of the entire system, enabling communication between the controllers of each DC-blocking device, and controlling each DC-blocking device through the linkage exit control branch to achieve synchronous operation, suppressing the influence of DC current on the transformer, avoiding faults of the transformer due to DC bias, and ensuring the safe and stable operation of the transformer.

[0096] In one embodiment, as Figure 9 shown, the global exit status monitoring branch 11 includes: a DC-blocking exit status switch and a global exit status switch. The control end of the DC-blocking exit status switch serves as the input end of the global exit status monitoring branch 11. One end of the DC-blocking exit status switch is connected to the power supply of the DC-blocking device, and the other end of the DC-blocking exit status switch serves as the second output end of the global exit status monitoring branch 11. The other end of the DC-blocking exit status switch is also connected to the input end of the global exit status switch, and the output end of the global exit status switch serves as the first output end of the global exit status monitoring branch 11.

[0097] Among them, as Figure 9 shown, the control end of the DC-blocking exit status switch is connected to the tenth port 110 of the controller, serving as the input end of the global exit status monitoring branch 11. One end of it is connected to the power supply, the other end is connected to the input end of the global exit status switch, and is connected to the second output ends of other global exit status monitoring branches through the twelfth port 112 of the controller, serving as the second output end of the global exit status monitoring branch 11. The output end of the global exit status switch serves as the first output end of the global exit status monitoring branch 11 and is connected to the eleventh port 111 of the controller. Among them, the DC-blocking exit status switch is a relay switch, and the global exit status switch is an optocoupler.

[0098] The working process of the above control circuit is as follows:

[0099] When the controller of the DC-blocking device detects that the DC current at the neutral point of the transformer connected to it is less than 50 A, that is, when the exit condition is met, the eighth port 108 of the controller sends a linkage exit control signal to the linkage exit control branch 9, causing the linkage exit control switch to close. When all the DC-blocking devices meet the exit condition, the linkage exit control branches 9 of all the DC-blocking devices form a DC-blocking exit loop, and the linkage exit control signal is transmitted through the DC-blocking exit loop to the input end of the linkage exit switch of the linkage exit control branch 9 of each DC-blocking device. After receiving the linkage exit control signal, the linkage exit switch closes, and the linkage exit execution signal is sent to the controller 1 through the ninth port 109 of the controller. The ninth port 109 of the controller obtains the linkage exit execution signal output by the linkage exit control branch 9 and disconnects the changeover switch on the transformer connection branch, causing the DC-blocking device to enter the exit state;

[0100] After the controllers 1 of all the DC-blocking devices detect that the DC-blocking devices enter the exit state, the tenth port 110 of the controller outputs a DC-blocking exit state monitoring signal to the input end of the global exit state monitoring branch 11. The DC-blocking exit state switch closes, disconnecting the power signal. When all the DC-blocking exit state switches are closed and all the power signals are disconnected, the DC-blocking exit state monitoring signal (which is 0 at this time) is transmitted to the global exit state switch of each DC-blocking device. The global exit state switch closes and transmits the global exit state monitoring signal to the controller 1 through the eleventh port 111 of the controller, realizing the synchronous exit of N DC-blocking devices;

[0101] When a certain one of the N DC-blocking devices fails and cannot exit synchronously with other DC-blocking devices, its DC-blocking exit state switch remains closed, and the global exit state switch still receives the power signal. At this time, the global exit state switch does not close, and the global exit state monitoring signal transmitted to the controller 1 is 1.

[0102] In this embodiment, by setting the DC-blocking exit state switch and the global exit state switch in the global exit state monitoring branch, it is ensured that only when all the DC-blocking devices have exited, the global exit state switch of the global exit state monitoring branch will send a global exit state monitoring signal of 0 to the controller, indicating that all the DC-blocking devices have achieved synchronous exit, ensuring that each DC-blocking device achieves synchronous exit, suppressing the influence of DC current on the transformer, avoiding the transformer from malfunctioning due to DC bias, and ensuring the safe and stable operation of the transformer.

[0103] In one embodiment, it further includes: a control host 5, such as Figure 9As shown, the control host 5 is respectively connected to the sixth port 106 of the controllers of each of the DC blocking devices, and is used to obtain the global exit status monitoring signals sent by each of the controllers 1, and determine whether the N DC blocking devices exit synchronously according to the N global exit status monitoring signals.

[0104] Among them, the working process of the above control circuit is as follows:

[0105] When the controller 1 of the DC blocking device detects that the DC current at the neutral point of the transformer connected to it is less than 50A, that is, when the exit condition is met, the eighth port 108 of the controller sends a linkage exit control signal to the linkage exit control branch 9, causing the linkage exit control switch to close. When all the DC blocking devices meet the exit conditions, the linkage exit control branches 9 of all the DC blocking devices form a DC blocking exit loop, and transmit the linkage exit control signal to the input end of the linkage exit switch of the linkage exit control branch 9 of each DC blocking device through the DC blocking exit loop. After receiving the linkage exit control signal, the linkage exit switch closes, and transmits the linkage exit execution signal to the controller 1 through the ninth port 109 of the controller. The ninth port 109 of the controller obtains the linkage exit execution signal output by the linkage exit control branch 9, and disconnects the switch on the transformer connection branch, so that the DC blocking device enters the exit state;

[0106] After the controllers 1 of all the DC blocking devices detect that the DC blocking devices enter the exit state, the tenth port 110 of the controller outputs a DC blocking exit status monitoring signal to the input end of the global exit status monitoring branch 11, and the DC blocking exit status switch closes, disconnecting the power signal. When all the DC blocking exit status switches are closed and all the power signals are disconnected, the DC blocking exit status monitoring signal (which is 0 at this time) is transmitted to the global exit status switch of each DC blocking device. The global exit status switch closes, and transmits the global exit status monitoring signal to the controller 1 through the eleventh port 111 of the controller. The controller 1 transmits the received DC blocking exit status monitoring signal to the control host 5, and the control host 5 determines that if the DC blocking exit status monitoring signal is 0, it is determined that the N DC blocking devices have exited synchronously;

[0107] When a certain one of the N DC-blocking devices fails and cannot exit synchronously with other DC-blocking devices, the DC-blocking exit status switch of this device remains closed, and the global exit status switch still receives a power signal. At this time, the global exit status switch does not close, and the global exit status monitoring signal transmitted to Controller 1 is 1. Controller 1 transmits the received DC-blocking exit status monitoring signal to Control Host 5, and at the same time transmits the alarm signal to Control Host 5 through Controller 1. If the DC-blocking exit status monitoring signal received by Control Host 5 is 1, it is determined that the synchronous exit of the N DC-blocking devices has not been achieved. At this time, the DC-blocking devices that have successfully exited remain in the exit state. At the same time, the position of the faulty DC-blocking device is determined according to the alarm signal, and the faulty DC-blocking device is removed from the system for maintenance. After the faulty device exits the system, it will not affect the normal operation of other DC-blocking devices in the system.

[0108] In this embodiment, the control host is connected to the sixth port of the controller of each DC-blocking device to obtain the global exit status monitoring signal, and determine whether the N DC-blocking devices exit synchronously according to the global exit status monitoring signal. The working states of the DC-blocking devices are centrally managed and monitored, and faults are detected and repaired in a timely manner when a fault occurs, ensuring that the N DC-blocking devices exit synchronously, suppressing the influence of the DC current on the transformer, avoiding faults of the transformer due to DC bias, and reducing the damage of the transformer equipment.

[0109] In one embodiment, the DC-blocking device further includes: a camera module, the input end of the camera module is used to obtain a first switch image containing the change-over switch on the transformer connection branch and a second switch image containing the DC-blocking exit status switch of the global exit status monitoring branch 11;

[0110] The output end of the camera module is connected to the seventh port of the controller, and is used to input the first switch image and the second switch image into the trained switch status monitoring model, and output the exit status of the change-over switch and the exit status of the DC-blocking exit status switch to Controller 1, and send the exit status of the change-over switch and the exit status of the DC-blocking exit status switch to Control Host 5 through the sixth port 106 of the controller;

[0111] The control host 5 is used to determine whether each DC-blocking device exits synchronously according to the exit status of the N change-over switches, and determine whether Controller 1 has a communication fault according to the exit status of the N DC-blocking exit status switches.

[0112] Among them, the camera module is used to obtain the first switch image and the second switch image, and output the first switch image and the second switch image captured in real time to the switch state monitoring model. The switch state monitoring model adopts a neural network with an encoder-decoder structure. The trained switch state monitoring model can be used to predict the withdrawal state of the switching switch and the withdrawal state of the DC-blocking withdrawal state switch. The training process of the switch state monitoring model is as follows: Input the first switch image sample and the second switch image sample with withdrawal state labels into the switch state monitoring model under the initial parameters, and use the cross-loss entropy function to calculate the deviation between the prediction result of the switch state monitoring model and the withdrawal state label. When the deviation reaches the preset condition, stop the model training, update the model parameters, and obtain the trained switch state monitoring model. The switch state monitoring model can implement the prediction of the withdrawal state of the switch through another set processor, or can be implemented through Controller 1.

[0113] The switch state monitoring model obtains the withdrawal state of the switching switch and the withdrawal state of the DC-blocking withdrawal state switch based on the first switch image and the second switch image, and outputs them to Controller 1, and then outputs them to the control host 5 through Controller 1 to determine whether a communication failure occurs.

[0114] The working process of the above control circuit is as follows:

[0115] When the controller 1 of the DC-blocking device detects that the DC current at the neutral point of the transformer connected to it is less than 50 A, that is, when the withdrawal condition is met, the eighth port 108 of the controller sends a linkage withdrawal control signal to the linkage withdrawal control branch 9, so that the linkage withdrawal control switch is closed. When all the DC-blocking devices meet the withdrawal conditions, the linkage withdrawal control branches 9 of all the DC-blocking devices form a DC-blocking withdrawal loop, and transmit the linkage withdrawal control signal to the input end of the linkage withdrawal switch of the linkage withdrawal control branch 9 of each DC-blocking device through the DC-blocking withdrawal loop. After receiving the linkage withdrawal control signal, the linkage withdrawal switch is closed, and the linkage withdrawal execution signal is sent to the controller 1 through the ninth port 109 of the controller. The ninth port 109 of the controller obtains the linkage withdrawal execution signal output by the linkage withdrawal control branch 9, and disconnects the switching switch on the transformer connection branch, so that the DC-blocking device enters the withdrawal state;

[0116] When the controllers 1 of all the DC-blocking devices detect that the DC-blocking devices enter the exit state, the tenth port 110 of the controller outputs a DC-blocking exit state monitoring signal to the input end of the global exit state monitoring branch 11. The DC-blocking exit state switch closes, disconnecting the power signal. When all the DC-blocking exit state switches are closed and all the power signals are disconnected, the DC-blocking exit state monitoring signal (which is 0 at this time) is transmitted to the global exit state switches of each DC-blocking device. The global exit state switches close, and the global exit state monitoring signal is transmitted to the controller 1 through the eleventh port 111 of the controller. The controller 1 transmits the received DC-blocking exit state monitoring signal to the control host 5. The control host 5 makes a determination. If the DC-blocking exit state monitoring signal is 0, it is determined that the synchronous exit of N DC-blocking devices is achieved;

[0117] If a communication failure occurs when the tenth port 110 of the controller outputs a DC-blocking exit state monitoring signal to the DC-blocking exit state switch of the global exit state monitoring branch 11, at this time the DC-blocking exit state switch closes, the global exit state monitoring signal is 1, but the control host 5 does not receive the warning signal. Then the camera module acquires the first switch image of the changeover switch on the transformer connection branch and the second image of the DC-blocking exit state switch of the global exit state monitoring branch 11, and transmits them to the controller 1 through the seventh port of the controller. The controller 1 outputs the exit state of the changeover switch and the exit state of the DC-blocking exit state switch to the control host 5 through the trained switch state monitoring model. The control host 5 makes a judgment. If the exit state of the changeover switch is open, but the exit state of the DC-blocking exit state switch is closed, the control host 5 determines that a communication failure has occurred, but the synchronous exit is achieved. At this time, only the faulty DC-blocking device exits the system for maintenance, and the other already exited DC-blocking devices remain in the exit state. After the faulty device exits the system, it will not affect the normal operation of other DC-blocking devices in the system.

[0118] In this embodiment, by setting the camera module to acquire the first switch image and the second switch image and output them to the controller, obtaining the exit state of the changeover switch and the input state of the DC-blocking exit state switch, and then outputting the exit state of the changeover switch and the exit state of the DC-blocking exit state switch to the monitoring host for judgment, it avoids the misjudgment caused by the communication failure, makes the control circuit more perfect, ensures that each DC-blocking device achieves synchronous exit, suppresses the influence of the DC current on the transformer, avoids the failure of the transformer due to DC bias, and prolongs the service life of the equipment.

[0119] The above-described 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 foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A control circuit for synchronous switching-on and switching-off of a DC isolation device for multiple transformers, characterized in that, Including: N DC-blocking devices, where N > 2, and the DC-blocking devices are cascaded with each other. Each of the DC-blocking devices includes: a controller, a linkage input control branch, and a transformer connection branch; The first port of the controller is connected to the input end of the linkage input control branch for sending a linkage input control signal to the linkage input control branch. The second port of the controller is connected to the first output end of the linkage input control branch for obtaining a linkage input execution signal. The third port of the controller is connected to the second output end of the linkage input control branch for providing a power signal to the linkage input control branch of other DC-blocking devices through the second output end of the linkage input control branch; The controller is connected to the switching switch on the transformer connection branch to control the closing of the switching switch on the transformer connection branch according to the linkage input execution signal, so as to realize the synchronous input of the N DC-blocking devices; Each of the DC-blocking devices further includes: a global input state monitoring branch. The input end of the global input state monitoring branch is connected to the fourth port of the controller for obtaining a DC-blocking input state monitoring signal output by the controller. The first output end of the global input state monitoring branch is connected to the fifth port of the controller for outputting a global input state monitoring signal to the controller. The second output ends of the global input state monitoring branches of each of the DC-blocking devices are connected to form a DC-blocking input state loop; Among them, the global input state monitoring branch includes: a DC-blocking input state switch and a global input state switch. The control end of the DC-blocking input state switch serves as the input end of the global input state monitoring branch. The two ends of the DC-blocking input state switch serve as the second output end of the global input state monitoring branch. The input end of the global input state switch is connected to the output end of the DC-blocking input state switch. The output end of the global input state switch serves as the first output end of the global input state monitoring branch.

2. The control circuit according to claim 1, wherein Also including: A control host, which is respectively connected to the sixth ports of the controllers of each of the DC-blocking devices for obtaining the global input state monitoring signals sent by each of the controllers, and determining whether the N DC-blocking devices are synchronously input according to the N global input state monitoring signals.

3. The control circuit according to claim 2, wherein The DC-blocking device further includes: a camera module. The input end of the camera module is used for obtaining a first switch image containing the switching switch on the transformer connection branch and a second switch image containing the DC-blocking input state switch of the global input state monitoring branch; The output end of the camera module is connected to the seventh port of the controller for inputting the first switch image and the second switch image into a trained switch state monitoring model, outputting the input state of the switching switch and the input state of the DC-blocking input state switch to the controller, and sending the input state of the switching switch and the input state of the DC-blocking input state switch to the control host through the sixth port of the controller; The control host is used to determine whether each DC-blocking device is synchronously put into operation according to the input states of the N switching switches, and determine whether the controller has a communication failure according to the input states of the N DC-blocking input state switches.

4. A control circuit for synchronous switching-on and switching-off of DC isolation devices of multiple transformers, characterized in that, It includes: N DC-blocking devices, where N>2, and the DC-blocking devices are connected in cascade with each other. Each DC-blocking device includes: a controller, a linkage withdrawal control branch, and a transformer connection branch; The eighth port of the controller is connected to the input end of the linkage withdrawal control branch, and is used to send a linkage withdrawal control signal to the linkage withdrawal control branch. The ninth port of the controller is connected to the first output end of the linkage withdrawal control branch, and is used to obtain a linkage withdrawal execution signal. The second output ends of the linkage withdrawal control branches of the DC-blocking devices are connected to form a DC-blocking withdrawal loop; The controller is connected to the switching switch on the transformer connection branch, and is used to control the switching switch on the transformer connection branch to disconnect according to the linkage withdrawal execution signal, so as to realize the synchronous withdrawal of the N DC-blocking devices; Each DC-blocking device further includes: a global withdrawal state monitoring branch. The input end of the global withdrawal state monitoring branch is connected to the tenth port of the controller, and is used to obtain the DC-blocking withdrawal state monitoring signal output by the controller. The first output end of the global withdrawal state monitoring branch is connected to the eleventh port of the controller, and is used to output a global withdrawal state monitoring signal to the controller. The twelfth port of the controller is connected to the second output end of the global withdrawal state monitoring branch, and is used to obtain the global withdrawal state monitoring signals of other DC-blocking devices through the second output end of the global withdrawal state monitoring branch; Among them, the global withdrawal state monitoring branch includes: a DC-blocking withdrawal state switch and a global withdrawal state switch. The control end of the DC-blocking withdrawal state switch is used as the input end of the global withdrawal state monitoring branch. One end of the DC-blocking withdrawal state switch is connected to the power supply of the DC-blocking device. The other end of the DC-blocking withdrawal state switch is used as the second output end of the global withdrawal state monitoring branch. The other end of the DC-blocking withdrawal state switch is also connected to the input end of the global withdrawal state switch. The output end of the global withdrawal state switch is used as the first output end of the global withdrawal state monitoring branch.

5. The control circuit according to claim 4, wherein It further includes: A control host, which is respectively connected to the sixth port of the controller of each DC-blocking device, and is used to obtain the global withdrawal state monitoring signals sent by each controller, and determine whether the N DC-blocking devices are synchronously withdrawn according to the N global withdrawal state monitoring signals.

6. The control circuit according to claim 5, wherein The DC-blocking device further includes: a camera module. The input end of the camera module is used to obtain a first switch image containing the switching switch on the transformer connection branch and a second switch image containing the DC-blocking withdrawal state switch of the global withdrawal state monitoring branch; The output end of the camera module is connected to the seventh port of the controller, and is used to input the first switch image and the second switch image into the trained switch state monitoring model, output the exit state of the change-over switch and the exit state of the DC-blocking exit state switch to the controller, and send the exit state of the change-over switch and the exit state of the DC-blocking exit state switch to the control host through the sixth port of the controller; The control host is used to determine whether each DC-blocking device exits synchronously according to the exit states of the N change-over switches, and determine whether the controller has a communication failure according to the exit states of the N DC-blocking exit state switches.

Images