Hierarchical reclosing control method and system of oscillation type direct current circuit breaker

Abstract

The invention discloses a grading reclosing control method and system of an oscillation type direct current circuit breaker, the oscillation type direct current circuit breaker is electrically connected between a direct current power supply and a load, and the oscillation type direct current circuit breaker comprises a main through-flow branch and an oscillation branch. Wherein the main through-flow branch is electrically connected between a direct-current power supply and a load; the main through-flow branch comprises at least two series-connected graded closing units, and each graded closing unit comprises a first switch and an energy consumption element which are connected in parallel; the oscillation branch is electrically connected between the direct-current power supply and the load; the method comprises the steps that under the condition of troubleshooting, the multiple first switches are controlled to be reclosed in a hierarchical mode, and the time when the multiple first switches are reclosed in the hierarchical control is different. According to the embodiment of the invention, the current can be gradually increased through grading reclosing, large current impact generated when all the first switches are switched on at the same time can be avoided, high-frequency oscillation generated when the first switches are switched on at the same time is avoided, and the stability and safety of the reclosing process are ensured.

Description

Technical Field

[0001] This application belongs to the field of DC power transmission technology, and in particular relates to a graded reclosing control method and system for an oscillating DC circuit breaker. Background Technology

[0002] In high-voltage direct current transmission systems, DC circuit breakers are key equipment to ensure rapid fault clearance and stable system operation.

[0003] Oscillating DC circuit breakers have become an important development direction due to their simple structure and suitability for economical high-voltage, high-capacity DC breaking scenarios. Oscillating DC circuit breakers mainly rely on a controllable voltage source and the LC circuit of the oscillating branch to generate forced resonance, transferring the main current to the oscillating branch, thereby enabling reliable interruption of the main current-carrying branch at the current zero-crossing point.

[0004] In actual high-voltage direct current (HVDC) transmission system operation, faults are difficult to completely avoid. To achieve rapid power restoration after a fault and reduce power outage time and impact on users, DC circuit breakers are equipped with reclosing functions. However, oscillating DC circuit breakers can induce high-frequency current oscillations during reclosing, causing strong transient stress on the vacuum switch and the entire power supply system, making it impossible to guarantee the smoothness and safety of the reclosing process. Summary of the Invention

[0005] This application provides a graded reclosing control method and system for an oscillating DC circuit breaker. By graded reclosing, the current can be gradually increased, which can avoid the large current surge when all the first switches are closed at the same time, avoid high-frequency oscillation when closing at the same time, and ensure the stability and safety of the reclosing process.

[0006] In a first aspect, embodiments of this application provide a graded reclosing control method for an oscillating DC circuit breaker, wherein the oscillating DC circuit breaker is electrically connected between a DC power supply and a load, and the oscillating DC circuit breaker includes:

[0007] The main current-carrying branch is electrically connected between the DC power supply and the load; the main current-carrying branch includes at least two series-connected staged closing units, and each staged closing unit includes a first switch and an energy-consuming element connected in parallel;

[0008] The oscillation branch is electrically connected between the DC power supply and the load;

[0009] The method includes:

[0010] In the event that the fault has been cleared, multiple first switches are reclosed in a tiered manner, with the timing of the reclosing of the multiple first switches being different.

[0011] In one possible embodiment of the first aspect, hierarchical control of multiple first switches for reclosing includes:

[0012] After controlling the i-th first switch to reclose at the first moment, obtain the current of the main current-carrying branch, where i is an integer greater than or equal to 1;

[0013] Based on the current in the main current-carrying branch, continue or stop the graded control.

[0014] In one possible embodiment of the first aspect, the graded control is continued or stopped based on the current of the main current-carrying branch, including:

[0015] If the rate of increase of the current in the main current-carrying branch is less than or equal to a preset threshold, the fault type is determined to be a temporary fault, and the (i+1)th first switch is controlled to reclose at the second moment.

[0016] In one possible embodiment of the first aspect, the oscillation branch includes an oscillation capacitor and an inductor; the time interval between the first moment and the second moment satisfies the following relationship:

[0017]

[0018] Where ΔT is the time interval between the first and second moments, and L ce C is the inductance value of the inductor. M This is the capacitance value of the oscillating capacitor.

[0019] In one possible embodiment of the first aspect, the graded control is continued or stopped based on the current of the main current-carrying branch, including:

[0020] If the rate of increase of the current in the main current-carrying branch exceeds a preset threshold, the fault type is determined to be a permanent fault, and all first switches are controlled to open.

[0021] Based on the same inventive concept, in a second aspect, embodiments of this application also provide a graded reclosing control system for an oscillating DC circuit breaker, including an oscillating DC circuit breaker and a controller. The oscillating DC circuit breaker is electrically connected between a DC power supply and a load. The oscillating DC circuit breaker includes:

[0022] The main current-carrying branch is electrically connected between the DC power supply and the load; the main current-carrying branch includes at least two series-connected staged closing units, and each staged closing unit includes a first switch and an energy-consuming element connected in parallel;

[0023] The oscillation branch is electrically connected between the DC power supply and the load;

[0024] The controller's multiple output terminals are electrically connected to the control terminals of multiple first switches, one by one.

[0025] The controller is configured as follows:

[0026] In the event that the fault has been cleared, multiple first switches are reclosed in a tiered manner, with the timing of the reclosing of the multiple first switches being different.

[0027] In one possible embodiment of the second aspect, it further includes:

[0028] The current sensor has its input terminal electrically connected to the main current-carrying branch and its output terminal electrically connected to the controller. It is used to collect and output the current of the main current-carrying branch.

[0029] The controller is configured as follows:

[0030] After controlling the i-th first switch to reclose at the first moment, the current of the main current-carrying branch collected by the current sensor is obtained, where i is an integer greater than or equal to 1;

[0031] Based on the current in the main current-carrying branch, continue or stop the graded control.

[0032] In one possible embodiment of the second aspect, the oscillation branch includes an oscillation capacitor and an inductor connected in series between the DC power supply and the load;

[0033] The oscillation branch also includes a first controllable voltage source, and the oscillation capacitor, inductor and the first controllable voltage source are connected in series between the DC power supply and the load;

[0034] The first controllable voltage source is either a full-bridge structure or a half-bridge structure.

[0035] In one possible embodiment of the second aspect, the oscillation branch includes an oscillation capacitor and an inductor connected in series between the DC power supply and the load;

[0036] The main current-carrying branch also includes a second controllable voltage source, and the second controllable voltage source and multiple staged closing units are connected in series between the DC power supply and the load;

[0037] The second controllable voltage source is a solid-state switch structure or a hybrid switch structure.

[0038] In one possible embodiment of the second aspect, the number of tiered closing units is positively correlated with the voltage level of the DC power supply.

[0039] In one possible embodiment of the second aspect, the first switch is a vacuum switch; the energy-consuming element is a metal oxide varistor.

[0040] Based on the same inventive concept, in a third aspect, embodiments of this application also provide a graded reclosing control device for an oscillating DC circuit breaker, the device including a processor and a memory storing computer program instructions; when the processor executes the computer program instructions, it implements the graded reclosing control method for the oscillating DC circuit breaker in the first aspect, or any embodiment of the first aspect.

[0041] Based on the same inventive concept, in a fourth aspect, embodiments of this application also provide a computer-readable storage medium storing computer program instructions, which, when executed by a processor, implement the first aspect, or the graded reclosing control method for an oscillating DC circuit breaker in any embodiment of the first aspect.

[0042] Based on the same inventive concept, in a fifth aspect, embodiments of this application also provide a computer program product, wherein when the instructions in the computer program product are executed by the processor of a device, the device is able to execute the graded reclosing control method for an oscillating DC circuit breaker in the first aspect or any embodiment of the first aspect.

[0043] The tiered reclosing control method and system for an oscillating DC circuit breaker provided in this application are as follows: The oscillating DC circuit breaker is electrically connected between a DC power supply and a load. Under normal operating conditions, the oscillating DC circuit breaker maintains the electrical connection between the DC power supply and the load, providing power to the load. When a circuit fault occurs, the oscillating DC circuit breaker disconnects the electrical connection between the DC power supply and the load, protecting both the load and the DC power supply. After the fault is cleared, the oscillating DC circuit breaker needs to perform a reclosing operation (referred to as reclosing) to restore the electrical connection between the DC power supply and the load, restoring normal power supply to the load. The oscillating DC circuit breaker may include a main current-carrying branch and an oscillating branch, which are connected in parallel and electrically connected between the DC power supply and the load. Specifically, the main current-carrying branch includes multiple series-connected tiered closing units. Each tiered closing unit includes a first switch connected in parallel and energy-consuming components. When the first switch needs to be reclosed after fault clearance, multiple first switches can be controlled to reclose in stages. Tiered control refers to controlling multiple first switches to reclose at different times. Tiered reclosing allows the current to gradually increase, avoiding large current surges when all first switches close simultaneously, preventing high-frequency oscillations during simultaneous closing, and ensuring the smoothness and safety of the reclosing process. Attached Figure Description

[0044] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals denote the same or similar features, and the drawings are not drawn to scale.

[0045] Figure 1-A This is a schematic diagram of a structure of an oscillating DC circuit breaker provided in an embodiment of this application;

[0046] Figure 1-B This is a schematic flowchart of a graded reclosing control method for an oscillating DC circuit breaker provided in an embodiment of this application;

[0047] Figure 2 This is another schematic flowchart of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application;

[0048] Figure 3 This is another schematic flowchart of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application;

[0049] Figure 4 This is another schematic flowchart of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application;

[0050] Figure 5 This is a schematic diagram of a graded reclosing control system for an oscillating DC circuit breaker provided in an embodiment of this application;

[0051] Figure 6 This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0052] Figure 7-A This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0053] Figure 7-B This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0054] Figure 7-C This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0055] Figure 8-A This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0056] Figure 8-B This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0057] Figure 8-C This is another structural schematic diagram of the graded reclosing control system for the oscillating DC circuit breaker provided in the embodiments of this application;

[0058] Figure 9 This is a schematic diagram of a graded reclosing process of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application;

[0059] Figure 10This is a waveform diagram illustrating the sequential reclosing of multiple first switches under a temporary fault in the graded reclosing control method for an oscillating DC circuit breaker provided in this application embodiment.

[0060] Figure 11 This is a schematic diagram of a graded reclosing control device for an oscillating DC circuit breaker provided in an embodiment of this application. Detailed Implementation

[0061] The features and exemplary embodiments of various aspects of this application will now be described in detail. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only configured to explain this application and are not configured to limit this application. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples of this application.

[0062] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0063] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0064] Various modifications and variations can be made to this application without departing from its spirit or scope, which will be apparent to those skilled in the art. Therefore, this application is intended to cover modifications and variations falling within the scope of the corresponding claims (the claimed technical solutions) and their equivalents. It should be noted that the embodiments provided in this application can be combined with each other without contradiction.

[0065] Before describing the technical solutions provided in the embodiments of this application, in order to facilitate understanding of the embodiments of this application, this application first specifically explains the problems existing in the related technologies:

[0066] In high-voltage direct current transmission systems, DC circuit breakers are key equipment to ensure rapid fault clearance and stable system operation.

[0067] Oscillating DC circuit breakers have become an important development direction due to their simple structure and suitability for economical high-voltage, high-capacity DC breaking scenarios. Oscillating DC circuit breakers mainly rely on a controllable voltage source and the oscillating capacitor and inductor of the oscillating branch to generate forced resonance, transferring the current of the main current-carrying branch to the oscillating branch, thereby reliably disconnecting the main current-carrying branch at the current zero-crossing point (the moment when the instantaneous value of the current is zero).

[0068] It should be noted that alternating current naturally has a zero-crossing point (the moment when the instantaneous value of the current is zero), which is crucial for the reliable arc extinguishing of AC circuit breakers. Direct current, however, does not have a natural zero-crossing point. Forcibly interrupting a continuously flowing large current (especially in high-voltage, high-capacity systems) will create a strong arc that is difficult to extinguish and may even burn out equipment. Therefore, DC breaking is more difficult than AC breaking. Although DC itself does not have a zero-crossing point, an oscillating DC circuit breaker can create one. The oscillating DC circuit breaker uses a controllable voltage source to drive an LC oscillating circuit to generate a high-frequency oscillating current superimposed on the DC current, forcibly canceling the main current and causing the composite current to reach a zero-crossing point, thus creating conditions for arc extinguishing or shutdown at the break point.

[0069] In the operation of high-voltage direct current (HVDC) transmission systems, oscillating DC circuit breakers are equipped with reclosing functions to achieve rapid power restoration after a fault, reduce power outage time and impact on users. When the controller determines that the fault is transient, reclosing the circuit breaker can avoid unnecessary power outages and manual intervention.

[0070] The inventors discovered that the reclosing strategy in related technologies typically involves closing all vacuum switches simultaneously. While simple, this method induces strong high-frequency current oscillations. Before the circuit breaker recloses, the oscillating capacitor maintains a high voltage. During reclosing, the controller closes all vacuum switches simultaneously, creating a closed circuit across the capacitor in a very short time. Because the capacitor voltage cannot change abruptly, this results in a significant current change in the circuit, leading to high-frequency current fluctuations. These high-frequency current oscillations exert strong transient stress on the vacuum switches and the entire power supply system, potentially causing contact erosion, insulation damage, and even affecting the stability of the entire power supply system, thus compromising the smoothness and safety of the reclosing process.

[0071] Based on this, the embodiments of this application provide a graded reclosing control method, device, equipment, medium and program product for an oscillating DC circuit breaker. By graded reclosing, the current can be gradually increased, which can avoid the large current surge when all the first switches are closed at the same time, avoid high-frequency oscillation when closing at the same time, and ensure the stability and safety of the reclosing process.

[0072] The graded reclosing control method for an oscillating DC circuit breaker provided in this application will be described in detail below with reference to the accompanying drawings.

[0073] Figure 1-A This is a schematic diagram of an oscillating DC circuit breaker provided in an embodiment of this application.

[0074] Figure 1-B This is a schematic flowchart of a graded reclosing control method for an oscillating DC circuit breaker provided in an embodiment of this application.

[0075] In one embodiment, such as Figure 1-A As shown, the oscillating DC circuit breaker 300 is electrically connected between the DC power supply 100 and the load 200. The oscillating DC circuit breaker 300 may include a main current-carrying branch 10 and an oscillating branch 20.

[0076] Under normal operating conditions, the oscillating DC circuit breaker 300 is in the closed state (conducting state) to maintain the electrical connection between the DC power supply 100 and the load 200, and to provide power to the load 200 based on the electrical energy of the DC power supply 100.

[0077] When a circuit fault occurs (such as a short circuit), the oscillating DC circuit breaker 300 switches to the open state (disconnected state) to cut off the electrical connection between the DC power supply 100 and the load 200, thereby protecting the DC power supply 100 and the load 200.

[0078] After the fault is cleared, the oscillating DC circuit breaker 300 needs to be reclosed to restore the electrical connection between the DC power supply 100 and the load 200, that is, to restore the normal power supply from the DC power supply 100 to the load 200.

[0079] For example, the fault can be identified by monitoring the current in the main current-carrying branch 10 in real time. If the current in the main current-carrying branch 10 is greater than or equal to a preset current threshold, it indicates that a short circuit fault has occurred. If the current in the main current-carrying branch 10 is less than the preset current threshold, it indicates that the fault has been eliminated.

[0080] The main current-carrying branch 10 is electrically connected between the DC power supply 100 and the load 200. The main current-carrying branch 10 includes at least two series-connected graded closing units 11, each graded closing unit 11 including a first switch 111 and an energy-consuming element 112 connected in parallel.

[0081] The oscillation branch 20 is electrically connected between the DC power supply 100 and the load 200.

[0082] For example, the first switch 111 can be a vacuum switch. Vacuum, as an insulating medium, has a high breaking capacity and a breaking speed of up to milliseconds. It matches the LC resonant period of the oscillation branch, can accurately control the current to turn off at the zero point, and can avoid equipment damage caused by arc reignition.

[0083] The energy-consuming element 112 can be a metal oxide varistor (MOV), which can quickly absorb overvoltage and avoid overvoltage.

[0084] When the first switch 111 is open, current flows through the energy-consuming element 112 connected in parallel with the first switch 111. When the first switch 111 is closed, the energy-consuming element 112 connected in parallel with the first switch 111 is short-circuited, and current flows through the first switch 111. This is equivalent to the resistance of the staged closing unit 11 decreasing, so the current in the entire main current-carrying branch will increase. Therefore, closing the first switch 111 one by one gradually increases the current, that is, staged reclosing can gradually increase the current.

[0085] like Figure 1-B As shown, the graded reclosing control method of the oscillating DC circuit breaker may include step S110.

[0086] S110, in the case of troubleshooting, multiple first switches 111 are reclosed in a hierarchical manner, and the hierarchical control includes the different times when the multiple first switches 111 are reclosed.

[0087] Among them, reclosing refers to reclosing after a fault has been recovered (i.e., in the absence of a fault).

[0088] Specifically, after the fault is cleared, the first switch 111 needs to be reclosed. Multiple first switches can be controlled to reclose at different times in a hierarchical manner.

[0089] For example, if there are N graded closing units 11, then there are N first switches 111. The first first switch 111 can be controlled to reclose at time t1, the second first switch 111 at time t2, ..., and so on, until the Nth first switch 111 recloses at time t... N Reclosing at specific times, where t1~t N At least two of the time points are different time points or any two of them are different time points. By using staged reclosing, the current can be gradually increased, which can avoid the large current surge when all the first switches 111 are closed at the same time, avoid high-frequency oscillation when closing at the same time, and ensure the smoothness and safety of the reclosing process.

[0090] According to the graded reclosing control method for an oscillating DC circuit breaker provided in this application embodiment, the oscillating DC circuit breaker 300 is electrically connected between the DC power supply 100 and the load 200. Under normal operating conditions, the oscillating DC circuit breaker 300 maintains the electrical connection between the DC power supply 100 and the load 200, providing power to the load 200. When a circuit fault occurs, the oscillating DC circuit breaker 300 disconnects the electrical connection between the DC power supply 100 and the load 200, protecting both the DC power supply 100 and the load 200. After the fault is cleared, the oscillating DC circuit breaker 300 needs to perform a reclosing operation to restore the electrical connection between the DC power supply 100 and the load 200, that is, to restore the normal power supply from the DC power supply 100 to the load 200. The oscillating DC circuit breaker 300 may include a main current-carrying branch 10 and an oscillating branch 20, which are connected in parallel and electrically connected between the DC power supply 100 and the load 200. Specifically, the main current-carrying branch 10 includes multiple series-connected graded closing units 11. Each graded closing unit 11 includes a first switch 111 connected in parallel and an energy-consuming element 112. When the first switch 111 needs to be reclosed after the fault is cleared, multiple first switches 111 can be controlled to reclose in a graded manner. Graded control refers to controlling multiple first switches 111 to reclose at different times. Through graded reclosing, the current can be gradually increased, which can avoid the large current surge when all first switches 111 are closed at the same time, avoid high-frequency oscillation when closing at the same time, and ensure the stability and safety of the reclosing process.

[0091] The following is combined with Figures 2-4 This section describes the specific process of step S110, which involves controlling N first switches 111 to reclose the circuit in a tiered manner after the fault has been cleared.

[0092] Figure 2 This is another schematic flowchart of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application.

[0093] In some embodiments, such as Figure 2 As shown, step S110 involves hierarchically controlling multiple first switches to reclose, which may include steps S111 and S112.

[0094] S111: After controlling the i-th first switch 111 to reclose at the first moment, obtain the current of the main current-carrying branch 10, where i is an integer greater than or equal to 1.

[0095] S112, based on the current in the main current-carrying branch 10, continues or stops the graded control.

[0096] Specifically, if a fault is detected and cleared at time t0 (e.g., the current in the main current-carrying branch 10 is less than a preset current threshold), a tiered reclosing control process is initiated. At time t1, the first switch 111 is controlled to perform a reclosing operation, and the current in the main current-carrying branch 10 is then measured. If the current in the main current-carrying branch 10 is still less than the preset threshold, at time t2, the second switch 111 is controlled to perform a reclosing operation, and the current in the main current-carrying branch 10 is measured. If the current in the main current-carrying branch 10 is still less than the preset threshold, at time t3, the third switch 111 is controlled to perform a reclosing operation, and so on, until all switches 111 are reclosed, restoring normal power supply. Time t1 is after time t0, time t2 is after time t1, time t3 is after time t2, and so on. In this embodiment, tiered reclosing allows the current to gradually increase, avoiding a large current surge when all switches 111 close simultaneously, preventing high-frequency oscillations during simultaneous closing, and ensuring the smoothness and safety of the reclosing process. During the graded reclosing process, once the current in the main current-carrying branch 10 is detected to be greater than or equal to the preset current threshold, all first switches 111 are immediately disconnected.

[0097] For example, step S112, based on the current in the main current-carrying branch, continues or stops the graded control, including:

[0098] If the current in the main current-carrying branch 10 is greater than or equal to the preset current threshold, all first switches 111 are disconnected; if the current in the main current-carrying branch 10 is less than the preset current threshold, the hierarchical control continues.

[0099] Specifically, during the tiered reclosing process, if the current in the main current-carrying branch 10 is greater than or equal to a preset current threshold, all first switches 111 can be disconnected. For example, once the current in the main current-carrying branch 10 is detected to be greater than or equal to the preset current threshold, it is determined to be a current abnormality, and all first switches 111 are immediately disconnected. Alternatively, if the current in the main current-carrying branch 10 is less than the preset current threshold, tiered control can continue, and the (i+1)th first switch 111 can be controlled to reclose at the next moment, and so on.

[0100] This embodiment controls the reclosing of the first switch in a tiered manner, gradually increasing the current in the main current-carrying branch. This effectively avoids the large current surge and high-frequency oscillation caused by the simultaneous closing of all switches, ensuring the stability of the reclosing process. Simultaneously, by monitoring the current in the main current-carrying branch in real time during the tiered closing process, it is possible to determine whether to continue or stop the tiered control based on the current in the main current-carrying branch, significantly improving the safety and reliability of the reclosing operation.

[0101] It should be noted that during the graded reclosing process, if the current in the main current-carrying branch 10 is detected to be greater than or equal to the preset current threshold, it is determined to be an abnormal current, and all first switches 111 are immediately disconnected; or, if the rate of increase of the current in the main current-carrying branch 10 is detected to be greater than the preset rate of increase threshold, it is determined to be an abnormal current, and all first switches 111 are immediately disconnected. This allows for early identification of faults such as short circuits, and even if the current does not reach the preset current threshold, it can respond quickly in the early stages of a fault.

[0102] Figure 3 This is another schematic flowchart of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application.

[0103] In some embodiments, such as Figure 3 As shown, step S112, which involves continuing or stopping the graded control based on the current in the main current-carrying branch 10, may include step S1121.

[0104] S1121, if the rate of increase of the current in the main current branch 10 is less than or equal to a preset threshold, the fault type is determined to be a temporary fault, and the (i+1)th first switch 111 is controlled to reclose at the second moment.

[0105] Among them, a temporary fault refers to a fault that occurs temporarily when the gate is opened (the opening occurs before the reclosing). After the fault is cleared, there will be no sudden increase in current when multiple first switches are reclosing in a hierarchical control manner, and multiple first switches can be reclosing normally in sequence.

[0106] Specifically, if after controlling the i-th first switch 111 to reclose, it is found that the current rise rate of the main current branch 10 is less than or equal to the preset rise rate threshold, then it means that the (i+1)-th first switch 111 can continue to be controlled to reclose. That is, if the current rise is slow, it means that the previous fault was only temporary and there is no fault now, so the reclosing command can continue to be issued. For example, if a fault is detected and cleared at time t0 (e.g., the current in the main current-carrying branch 10 is less than a preset current threshold), a tiered reclosing process can be initiated. At time t1, the first switch 111 can be controlled to perform a reclosing operation, and the current in the main current-carrying branch 10 can be obtained. If the rate of increase of the current in the main current-carrying branch 10 is less than a preset rate of increase threshold, the second switch 111 can be controlled to perform a reclosing operation at time t2, and the current in the main current-carrying branch 10 can be obtained. If the rate of increase of the current in the main current-carrying branch 10 is less than a preset rate of increase threshold, the third switch 111 can be controlled to perform a reclosing operation at time t3, and so on, until all switches 111 are reclosed and normal power supply is restored. Tiered reclosing allows the current to gradually increase, avoiding large current surges when all switches 111 are closed simultaneously, preventing high-frequency oscillations during simultaneous closing, and ensuring the smoothness and safety of the reclosing process. During the graded reclosing process, once the rising rate of the current in the main current-carrying branch 10 is detected to be greater than or equal to the preset rising rate threshold, all first switches 111 are immediately disconnected.

[0107] This embodiment controls the reclosing of the first switch in a tiered manner, gradually increasing the current in the main current-carrying branch. This effectively avoids the large current surge and high-frequency oscillation caused by all switches closing simultaneously, ensuring the stability of the reclosing process. Simultaneously, the main current-carrying branch current is monitored in real time during the tiered closing process. Once the current rise rate is detected to be greater than a preset rise rate threshold, all switches are immediately disconnected, allowing for early identification of faults such as short circuits. Even if the current does not reach the preset current threshold, a rapid response can be achieved in the early stages of a fault, significantly improving the safety and reliability of the reclosing operation and the system.

[0108] In some embodiments, the oscillation branch 20 may include an oscillation capacitor 21 and an inductor 22. The time interval between the first moment and the second moment satisfies the following relationship:

[0109]

[0110] Where ΔT is the time interval between the first and second moments, and L ce C is the inductance value of inductor 22. M This is the capacitance value of the oscillation capacitor 21.

[0111] in, This is the inherent oscillation period of the circuit.

[0112] Specifically, the time interval ΔT between adjacent reclosing operations should not be too small. ΔT should be greater than or equal to the inherent oscillation period of the circuit to avoid large-amplitude current oscillations caused by the oscillating current not being sufficiently attenuated before reclosing due to the short closing interval.

[0113] In this embodiment, the time interval ΔT between two adjacent reclosing operations is set to be greater than or equal to the inherent oscillation period of the oscillation branch. This ensures that the oscillating current has sufficiently decayed before each closing, effectively avoiding the problem of large-amplitude current oscillations due to excessively short closing intervals, and further improving the stability and safety of the reclosing process.

[0114] Figure 4 This is another schematic flowchart of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application.

[0115] In some embodiments, such as Figure 4 As shown, step S112 may include step S1122, which involves continuing or stopping the graded control based on the current in the main current-carrying branch 10.

[0116] S1122, if the rate of increase of the current in the main current branch 10 is greater than a preset threshold, determine that the fault type is a permanent fault and control all first switches 111 to open.

[0117] In this context, a permanent fault refers to a fault that occurs during the opening of the circuit breaker (before reclosing) and is not temporary; it will recur even after the fault is cleared. Therefore, a sudden increase in current will occur during the reclosing of multiple first switches in a tiered control system. Related technologies employ simultaneous reclosing for both temporary and permanent faults, which carries the risk of overcurrent damage to the equipment.

[0118] Specifically, if after controlling the i-th first switch 111 to reclose, it is found that the current rise rate of the main current branch 10 is greater than the preset rise rate threshold, it means that the current rises too fast, indicating that the fault has reappeared after the previous fault was cleared. In other words, the previous fault was not a temporary fault but a permanent fault. At this time, it is necessary to control all first switches 111 to open.

[0119] In the tiered reclosing process, this application embodiment can quickly identify fault types (such as temporary or permanent faults) by monitoring the rise rate of the main current-carrying branch. When the i-th first switch 111 detects that the rise rate of the main current-carrying branch exceeds a preset rise rate threshold after reclosing, it is immediately determined to be a permanent fault and all first switches are disconnected. This effectively avoids the problem of equipment overcurrent damage caused by blindly reclosing without eliminating permanent faults, and improves the intelligence level of the reclosing process and the safety of system operation.

[0120] Figure 5 This is a schematic diagram of a hierarchical reclosing control system for an oscillating DC circuit breaker provided in an embodiment of this application.

[0121] Based on the same inventive concept, such as Figure 5 As shown in the figure, this application embodiment also provides a graded reclosing control system 1000 for an oscillating DC circuit breaker, including an oscillating DC circuit breaker 300 and a controller 400. The oscillating DC circuit breaker is electrically connected between a DC power supply 100 and a load 200. The oscillating DC circuit breaker 300 includes a main current-carrying branch 10 and an oscillating branch 20.

[0122] The main current-carrying branch 10 is electrically connected between the DC power supply 100 and the load 200. The main current-carrying branch 10 includes at least two series-connected graded closing units 11, each graded closing unit 11 including a first switch 111 and an energy-consuming element 112 connected in parallel.

[0123] The oscillation branch 20 is electrically connected between the DC power supply 100 and the load 200.

[0124] The multiple output terminals of the controller 400 are electrically connected to the control terminals of the multiple first switches 111 respectively.

[0125] Controller 400 is configured as follows:

[0126] In the event that the fault has been cleared, multiple first switches 111 are reclosed in a tiered manner, and the tiered control includes the fact that the multiple first switches 111 reclose at different times.

[0127] According to the embodiment of this application, the graded reclosing control system 1000 for an oscillating DC circuit breaker may include an oscillating DC circuit breaker 300 and a controller 400. The oscillating DC circuit breaker 300 is electrically connected between a DC power supply 100 and a load 200. Under normal operating conditions, the oscillating DC circuit breaker 300 maintains the electrical connection between the DC power supply 100 and the load 200, providing power to the load 200. When a circuit fault occurs, the oscillating DC circuit breaker 300 disconnects the electrical connection between the DC power supply 100 and the load 200, protecting both the DC power supply 100 and the load 200. After the fault is cleared, the oscillating DC circuit breaker 300 needs to perform a reclosing operation to restore the electrical connection between the DC power supply 100 and the load 200, that is, to restore the normal power supply from the DC power supply 100 to the load 200. The oscillating DC circuit breaker 300 may include a main current-carrying branch 10 and an oscillating branch 20. The main current-carrying branch 10 and the oscillating branch 20 are connected in parallel and electrically connected between the DC power supply 100 and the load 200. Specifically, the main current-carrying branch 10 includes multiple series-connected graded closing units 11. Each graded closing unit 11 includes a first switch 111 connected in parallel and an energy-consuming element 112. Multiple output terminals of the controller 400 are electrically connected to the control terminals of the multiple first switches 111 respectively. Therefore, when a reclosing operation of the first switch 111 is required after fault clearing, the multiple output terminals of the controller 400 can control the multiple first switches 111 to reclose in a graded manner. Graded control refers to controlling the multiple first switches 111 to reclose at different times. Through graded reclosing, the current can gradually increase, which can avoid the large current surge when all the first switches 111 close simultaneously, avoid high-frequency oscillation when closing simultaneously, and ensure the smoothness and safety of the reclosing process.

[0128] It should be noted that in related technologies, one output terminal of the controller is connected to the control terminals of N first switches, and all N first switches reclose simultaneously upon fault recovery. In this embodiment, the controller has multiple output terminals, each connected to the control terminals of N first switches, and controls the N first switches to reclose sequentially in stages upon fault recovery. For example, the multiple first switches may include K1 to KN. The controller can control K1 to reclose at time t1, K2 to reclose at time t2, ..., KN to reclose at time tN. This staged closing allows the current to gradually increase, avoiding a large current surge when all first switches close simultaneously, preventing high-frequency oscillations during simultaneous closing, and ensuring the smoothness and safety of the reclosing process. Simultaneously, the main current branch is monitored in real time during the staged closing process. Once the current rise rate is detected to be greater than a preset rise rate threshold, all switches are immediately disconnected, allowing for early identification of faults such as short circuits. Even if the current does not reach the preset current threshold, a rapid response can be achieved in the early stages of a fault, realizing rapid response to fault conditions and further improving the safety and reliability of the reclosing operation.

[0129] In some embodiments, such as Figure 6 As shown, the graded reclosing control system 1000 of the oscillating DC circuit breaker may also include a current sensor 500.

[0130] The input terminal of the current sensor 500 is electrically connected to the main current-carrying branch 10, and the output terminal of the current sensor 500 is electrically connected to the controller 400, used to collect the current of the main current-carrying branch 10 and output it.

[0131] The current sensor 30 can be either a Hall sensor or a shunt, both capable of detecting the magnitude and direction of the current. A Hall sensor is a magnetic field sensor based on the Hall effect, a non-contact sensor with good isolation performance. A shunt, on the other hand, is based on the voltage division principle of a resistor; it calculates the circuit current based on the voltage generated across the resistor when current flows through it. It has a simple structure, low cost, and is a contact measurement method. In this embodiment, the current sensor 30 can be either a Hall sensor or a shunt; the user can choose the appropriate sensor type according to their actual needs.

[0132] Controller 400 is configured as follows:

[0133] After controlling the i-th first switch 111 to reclose at the first moment, the current of the main current-carrying branch 10 collected by the current sensor 500 is obtained, where i is an integer greater than or equal to 1.

[0134] Based on the current in the main current-carrying branch 10, the hierarchical control can be continued or stopped.

[0135] In this embodiment, if no abnormal current is detected during the graded reclosing process, graded control can continue until all first switches have completed their reclosing operations. By controlling the first switches to reclose sequentially in stages, the current in the main current-carrying branch gradually increases, effectively avoiding the large current surge and high-frequency oscillation caused by all switches closing simultaneously, thus ensuring the stability of the reclosing process. At the same time, if an abnormal current is detected during the graded closing process, all first switches are immediately disconnected, achieving rapid response to fault conditions. This effectively avoids equipment overcurrent damage caused by all first switches closing simultaneously, improving the safety of the reclosing operation and the reliability of the system.

[0136] It should be noted that, based on whether the controllable voltage source contains a pre-charged capacitor for driving, oscillating DC circuit breakers can be divided into two categories: active and passive. Among them, passive oscillating DC circuit breakers rely on the pre-charged oscillating capacitor and the current-limiting inductor to form a natural LC oscillation, requiring no external drive. They have the characteristics of simpler structure and more direct control. The graded reclosing control method for oscillating DC circuit breakers provided in this application embodiment is applicable to both passive and active oscillating DC circuit breakers.

[0137] In some embodiments, such as Figure 7-A As shown, the oscillation branch 20 may include an oscillation capacitor 21 and an inductor 22 connected in series between the DC power supply 100 and the load 200.

[0138] The oscillation branch 20 also includes a first controllable voltage source 23, and the oscillation capacitor 21, inductor 22 and the first controllable voltage source 23 are connected in series between the DC power supply 100 and the load 200.

[0139] The first controllable voltage source 23 is a full-bridge structure (see...). Figure 7-B ) or half-bridge structure (see Figure 7-C ).

[0140] See Figure 7-B The first controllable voltage source 23 can be located in the oscillation branch 20 and is a full-bridge structure. The first controllable voltage source 23 of the full-bridge structure includes a pre-charge capacitor C. E Power electronic switches T1 to T4 are connected in anti-parallel to each other. Diode D1, D2, D3, and D4 are connected in anti-parallel to each other across power electronic switch T1 and T2, T3, T3, and T4, respectively. During reclosing, T1 and T4 remain off, while T2 and T3 remain on. Current flows through T2, T3, or their anti-parallel diodes (depending on the current flow direction).

[0141] See Figure 7-CThe first controllable voltage source 23 can be located in the oscillation branch 20 and is a half-bridge structure. The first controllable voltage source 23 of the half-bridge structure includes a pre-charge capacitor C. E Power electronic switches T1 and T2 are connected. Diode D1 is connected in anti-parallel across power electronic switch T1, and diode D2 is connected in anti-parallel across power electronic switch T2. During reclosing, T1 remains off, while T2 remains on. Current flows through T2 or its anti-parallel diode (depending on the current flow direction).

[0142] The graded reclosing control method provided in this application embodiment can be applied to passive oscillating DC circuit breakers. Specifically, it can be applied to passive oscillating DC circuit breakers that integrate oscillating capacitors, inductors, and a full-bridge structure controllable voltage source, and it can also be applied to passive oscillating DC circuit breakers that integrate oscillating capacitors, inductors, and a half-bridge structure controllable voltage source.

[0143] In some embodiments, such as Figure 8-A As shown, the oscillation branch 20 includes an oscillation capacitor 21 and an inductor 22 connected in series between the DC power supply 100 and the load 200.

[0144] The main current-carrying branch 10 also includes a second controllable voltage source 12, and the second controllable voltage source 12 and multiple staged closing units 11 are connected in series between the DC power supply 100 and the load 200.

[0145] The second controllable voltage source 12 is a solid-state switch structure (see...). Figure 8-B ) or hybrid switching structure (see Figure 8-C ).

[0146] See Figure 8-B The second controllable voltage source 12 can be located in the main current-carrying branch 10 and is a solid-state switch structure. The second controllable voltage source 12 with the solid-state switch structure may include a set of power electronic devices T1, four diodes D1 to D4, a buffer resistor R, a buffer capacitor C, and a voltage-limiting surge arrester MOV. During the reclosing process, T1 remains in the off state, and the current flows through the voltage-limiting surge arrester MOV.

[0147] See Figure 8-C The second controllable voltage source 12 can be located in the main current-carrying branch 10 and has a hybrid switching structure. The second controllable voltage source 12 with the hybrid switching structure may include a mechanical switch, a set of power electronic devices T1, four diodes D1 to D4, a buffer resistor R, a buffer capacitor C, and a voltage-limiting surge arrester MOV. During reclosing, the mechanical switch remains open, T1 remains closed, and current flows through the voltage-limiting surge arrester MOV.

[0148] The hierarchical reclosing control method provided in this application can be applied to passive oscillating DC circuit breakers (integrating oscillating capacitors, inductors, and full-bridge / half-bridge controllable voltage sources) as well as active oscillating DC circuit breakers (integrating oscillating capacitors, inductors, and controllable voltage sources with solid-state / hybrid switching structures), and can meet the needs of different application scenarios.

[0149] It should be noted that the controllable voltage sources (such as the first controllable voltage source 23 and the second controllable voltage source 12) do not operate during the reclosing process of the first switch, but operate when the first switch is opened. The control terminal of the controllable voltage source (such as the gate of the power electronic switch) is electrically connected to the output terminal of the controller. In the event of a short-circuit fault (abnormal current), it generates a voltage signal in response to the opening command output by the controller, so as to force the oscillating capacitor and inductor to resonate and transfer the main current to the oscillating branch. This allows for reliable interruption of the main current branch at the current zero-crossing point (the moment when the instantaneous current value is zero).

[0150] Figure 9 This is a schematic diagram of a graded reclosing process of the graded reclosing control method for an oscillating DC circuit breaker provided in the embodiments of this application.

[0151] In one example, such as Figure 9 As shown, when the fault is cleared, the controller can control multiple first switches 111 to reclose in sequence, and the reclosing times of the multiple first switches 111 are different.

[0152] like Figure 9 As shown, each of the first switches 111 has a power dissipation element 112 connected in parallel across its two ends, such as a metal oxide varistor (MOV) to prevent overvoltage. At the initial time t1, only the first switch 111 is closed. At this time, since the other first switches 111 are in the open state, the current path will pass through the power dissipation element 112 connected in parallel with the other first switches. At this time, the current is very small and there will be no violent fluctuations. Then, the second switch 111 to the Nth second switch 111 are turned on step by step according to the timing sequence. After each closing, the oscillating current will not be too large and will decay rapidly, ensuring that the circuit current can oscillate to a stable value during the time interval ΔT between two reclosings. The current flowing through the vacuum switch during the closing process will not oscillate significantly.

[0153] The entire closing process is like constructing a stepped current path, causing the current in the main current-carrying branch to gradually increase, effectively avoiding the current surge caused by concentrated closing. Assuming a temporary fault is detected during the reclosing process, system operation needs to be restored as quickly as possible. A tiered reclosing strategy is adopted, simulating a typical reclosing waveform of 10 groups of first switches 111 closing sequentially, as shown below. Figure 10As shown, K1 represents the first first switch 111, K2 represents the second first switch 111, ..., K10 represents the tenth first switch 111. Before the staged reclosing, the voltage of the oscillating capacitor is relatively large. As K1 to K10 are closed in sequence, the voltage across the oscillating capacitor decreases stepwise, and the current in the main current-carrying branch gradually increases.

[0154] In actual operation, if a permanent fault occurs during the graded reclosing process, the current rise rate will be significantly faster than in the case of a transient fault. The controller can determine the fault type after some of the first switches are closed, quickly interrupt the closing command of the remaining first switches, and re-drive all closed first switches to open, thereby quickly achieving secondary shutdown and effectively avoiding secondary impact on the source side or load side due to the rapid rise of fault current when a permanent fault occurs.

[0155] Specifically:

[0156] 1) At time t0, if the controller detects that the fault has been cleared, it will start the graded reclosing process.

[0157] 2) At time t1, control the first switch 111 to reclose.

[0158] After controlling the reclosing of the first switch 111, the current of the main current-carrying branch is monitored. If the rate of increase of the current in the main current-carrying branch is less than the preset rate of increase threshold, the second switch 111 is controlled to reclose at time t2.

[0159] The time interval ΔT between time t2 and time t1 satisfies the following relationship:

[0160]

[0161] In the formula, L ce C is the inductance value of the inductor. M This is the capacitance value of the oscillating capacitor.

[0162] Alternatively, if the rate of increase of the current in the main current-carrying branch is greater than or equal to a preset rate of increase threshold, control all first switches 111 to close.

[0163] 3) At time t2, control the second first switch 111 to reclose.

[0164] After controlling the reclosing of the second first switch 111, the current of the main current-carrying branch is monitored. If the rate of increase of the current in the main current-carrying branch is less than the preset rate of increase threshold, the third first switch 111 is controlled to reclose at time t3.

[0165] The time interval ΔT between time t3 and time t2 satisfies the following relationship:

[0166]

[0167] In the formula, L ce C is the inductance value of the inductor. M This is the capacitance value of the oscillating capacitor.

[0168] Alternatively, if the rate of increase of the current in the main current-carrying branch is greater than or equal to a preset rate of increase threshold, control all first switches 111 to close.

[0169] And so on.

[0170] The tiered reclosing control method provided in this application can significantly reduce the peak current oscillation during the reclosing process without significantly increasing system complexity, alleviate transient stress on core components such as vacuum switches, and improve fault identification capabilities, effectively avoiding secondary impacts on the system in the event of a permanent fault. This tiered reclosing control method is applicable to various types of oscillating DC circuit breakers, and is particularly suitable for high-voltage, high-capacity DC circuit breakers using a large number of vacuum switches connected in series. It can ensure the smoothness and safety of the reclosing process and has strong fault identification capabilities.

[0171] In one example, the number of tiered closing units 11 is positively correlated with the voltage level of the DC power supply 100.

[0172] In this embodiment, the higher the voltage level of the DC power supply 100, the more graded closing units 11 are set up, which can reliably shut off when closing and effectively suppress transient impacts through the step-like current increase during graded reclosing.

[0173] Figure 11 A schematic diagram of the hardware structure of the graded reclosing control device for an oscillating DC circuit breaker provided in an embodiment of this application is shown.

[0174] The graded reclosing control device of the oscillating DC circuit breaker may include a processor 1101 and a memory 1102 storing computer program instructions.

[0175] Specifically, the processor 1101 may include a central processing unit (CPU), an application specific integrated circuit (ASIC), or one or more integrated circuits that can be configured to implement the embodiments of this application.

[0176] Memory 1102 may include a large-capacity memory for data or instructions. For example, and not limitingly, memory 1102 may include a hard disk drive (HDD), a floppy disk drive, flash memory, optical disk, magneto-optical disk, magnetic tape, or a Universal Serial Bus (USB) drive, or a combination of two or more of these. Where suitable, memory 1102 may include removable or non-removable (or fixed) media. Where suitable, memory 1102 may be internal or external to the graded reclosing control device of an oscillating DC circuit breaker. In a particular embodiment, memory 1102 is a non-volatile solid-state memory.

[0177] Memory may include read-only memory (ROM), random access memory (RAM), disk storage media devices, optical storage media devices, flash memory devices, and electrical, optical, or other physical / tangible memory storage devices. Therefore, typically, memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., memory devices) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to one aspect of this disclosure.

[0178] The processor 1101 reads and executes computer program instructions stored in the memory 1102 to implement any of the graded reclosing control methods for oscillating DC circuit breakers in the above embodiments.

[0179] In one example, the graded reclosing control device for an oscillating DC circuit breaker may further include a communication interface 1103 and a bus 1104. Wherein, as Figure 11 As shown, the processor 1101, memory 1102, and communication interface 1103 are connected through bus 1104 and complete communication with each other.

[0180] The communication interface 1103 is mainly used to realize communication between various modules, devices, units and / or equipment in the embodiments of this application.

[0181] Bus 1104 includes hardware, software, or both, that couples the components of the graded reclosing control device for an oscillating DC circuit breaker together. For example, and not limited to, the bus may include an Accelerated Graphics Port (AGP) or other graphics bus, an Extended Industry Standard Architecture (EISA) bus, a Front Side Bus (FSB), a Hyper Transport (HT) interconnect, an Industry Standard Architecture (ISA) bus, an Infinite Bandwidth Interconnect, a Linear Predictive Coding (LPC) bus, a memory bus, a MicroChannel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (Peripheral Component Interconnect-X, PCI-X) bus, a Serial Advanced Technology Attachment (SATA) bus, a Video Electronics Standards Association Local Bus (VESA Local Bus, VLB) bus, or other suitable buses, or a combination of two or more of these. Where appropriate, bus 1104 may include one or more buses. Although specific buses are described and illustrated in embodiments of this application, any suitable bus or interconnection is contemplated herein.

[0182] This device can execute the graded reclosing control method of the oscillating DC circuit breaker in this application embodiment based on each unit / component in the graded reclosing control device of the oscillating DC circuit breaker, thereby achieving a combination of Figures 1-B to 4 The described method is a graded reclosing control method for an oscillating DC circuit breaker.

[0183] Furthermore, in conjunction with the graded reclosing control method for the oscillating DC circuit breaker in the above embodiments, this application embodiment can provide a computer storage medium for implementation. This computer storage medium stores computer program instructions; when these computer program instructions are executed by a processor, they implement any of the graded reclosing control methods for the oscillating DC circuit breaker in the above embodiments.

[0184] This application also provides a computer program product, wherein the instructions in the computer program product, when executed by the processor of an electronic device, cause the electronic device to perform various processes implementing any of the above-described embodiments of the graded reclosing control method for an oscillating DC circuit breaker.

[0185] It should be clarified that this application is not limited to the specific configurations and processes described above and shown in the figures. For the sake of brevity, detailed descriptions of known methods are omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of this application is not limited to the specific steps described and shown. Those skilled in the art can make various changes, modifications, and additions, or change the order of steps, after understanding the spirit of this application.

[0186] The functional blocks shown in the above-described block diagram can be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, they can be, for example, electronic circuits, application-specific integrated circuits (ASICs), appropriate firmware, plug-ins, function cards, etc. When implemented in software, the elements of this application are programs or code segments used to perform the required tasks. Programs or code segments can be stored on a machine-readable medium or transmitted over a transmission medium or communication link via data signals carried on a carrier wave. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, read-only memory (ROM), flash memory, erasable read-only memory (EROM), floppy disks, compact disc read-only memory (CD-ROM), optical disks, hard disks, fiber optic media, radio frequency (RF) links, etc. Code segments can be downloaded via computer networks such as the Internet, intranets, etc.

[0187] It should also be noted that the exemplary embodiments mentioned in this application describe methods or systems based on a series of steps or apparatus. However, this application is not limited to the order of the above steps; that is, the steps can be performed in the order mentioned in the embodiments, or in a different order, or several steps can be performed simultaneously.

[0188] The aspects of this disclosure have been described above with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this disclosure. It should be understood that each block in 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, a special-purpose computer, or other programmable data processing apparatus to produce a machine such that these instructions, executable via the processor of the computer or other programmable data processing apparatus, enable the implementation of the functions / actions specified in one or more blocks of the flowchart illustrations and / or block diagrams. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field-programmable logic circuit. It is also understood that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can also be implemented by special-purpose hardware performing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0189] The above are merely specific embodiments of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A graded reclosing control method for an oscillating DC circuit breaker, characterized in that, The oscillating DC circuit breaker is electrically connected between the DC power supply and the load, and the oscillating DC circuit breaker includes: The main current-carrying branch is electrically connected between the DC power supply and the load; the main current-carrying branch includes at least two series-connected graded closing units, and the graded closing unit includes a first switch and an energy-consuming element connected in parallel; An oscillation branch is electrically connected between the DC power supply and the load; The method includes: In the event that the fault has been cleared, multiple first switches are reclosed in a tiered manner, wherein the tiered control includes the reclosing of multiple first switches at different times.

2. The method according to claim 1, characterized in that, The hierarchical control of multiple first switches to reclose includes: After controlling the i-th first switch to reclose at the first moment, the current of the main current-carrying branch is obtained, where i is an integer greater than or equal to 1; The graded control is continued or stopped based on the current in the main current-carrying branch.

3. The method according to claim 2, characterized in that, The step of continuing or stopping the graded control based on the current of the main current-carrying branch includes: If the rate of increase of the current in the main current-carrying branch is less than or equal to a preset threshold, the fault type is determined to be a temporary fault, and the (i+1)th first switch is controlled to reclose at the second moment.

4. The method according to claim 3, characterized in that, The oscillation branch includes an oscillation capacitor and an inductor; the time interval between the first moment and the second moment satisfies the following relationship: Wherein, ΔT is the time interval between the first time point and the second time point, and L... ce The inductance value of the inductor, C M The capacitance value of the oscillating capacitor.

5. The method according to claim 2, characterized in that, The step of continuing or stopping the graded control based on the current of the main current-carrying branch includes: If the rate of increase of the current in the main current-carrying branch exceeds a preset threshold, the fault type is determined to be a permanent fault, and all the first switches are controlled to open.

6. A graded reclosing control system for an oscillating DC circuit breaker, characterized in that, The circuit breaker includes an oscillating DC circuit breaker and a controller, wherein the oscillating DC circuit breaker is electrically connected between a DC power supply and a load, and the oscillating DC circuit breaker includes: The main current-carrying branch is electrically connected between the DC power supply and the load; the main current-carrying branch includes at least two series-connected graded closing units, and the graded closing unit includes a first switch and an energy-consuming element connected in parallel; An oscillation branch is electrically connected between the DC power supply and the load; The controller's multiple output terminals are electrically connected to the control terminals of the multiple first switches one by one; The controller is configured to: In the event that the fault has been cleared, multiple first switches are reclosed in a tiered manner, wherein the tiered control includes the reclosing of multiple first switches at different times.

7. The system according to claim 6, characterized in that, Also includes: A current sensor, the input terminal of which is electrically connected to the main current-carrying branch, and the output terminal of which is electrically connected to the controller, are used to collect and output the current of the main current-carrying branch; The controller is configured to: After controlling the i-th first switch to reclose at the first moment, the current of the main current-carrying branch collected by the current sensor is obtained, where i is an integer greater than or equal to 1; The graded control is continued or stopped based on the current in the main current-carrying branch.

8. The system according to claim 6, characterized in that, The oscillation branch includes an oscillation capacitor and an inductor connected in series between the DC power supply and the load; The oscillation branch further includes a first controllable voltage source, and the oscillation capacitor, the inductor and the first controllable voltage source are connected in series between the DC power supply and the load; The first controllable voltage source is a full-bridge structure or a half-bridge structure.

9. The system according to claim 6, characterized in that, The oscillation branch includes an oscillation capacitor and an inductor connected in series between the DC power supply and the load; The main current-carrying branch also includes a second controllable voltage source, and the second controllable voltage source and multiple of the staged closing units are connected in series between the DC power supply and the load; The second controllable voltage source is a solid-state switch structure or a hybrid switch structure.

10. The system according to any one of claims 6 to 9, characterized in that, The first switch is a vacuum switch; the energy-consuming element is a metal oxide varistor.

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