A series resonant circuit breaker staged breaking system, method, and storage medium

Abstract

The present application relates to the technical field of electronic power system segmentation protection, in particular to a series oscillation type circuit breaker hierarchical breaking system and method and storage medium. When the circuit current exceeds the preset fault value, the self-protection breaking module can firstly automatically perform the circuit breaking action locally to complete the primary circuit breaking, increase the circuit impedance in advance, and suppress the rising rate and peak value of the circuit current. After the upper control system detects that the circuit generates a real fault current, it controls the controlled breaking module to perform the circuit breaking action with a delay to complete the secondary circuit breaking. At this time, the current value that the controlled breaking module needs to break is reduced, and the breaking burden and difficulty are significantly reduced. Finally, the time-delay hierarchical breaking of the two types of breaking modules is realized. Compared with the traditional synchronous breaking mode, the action response time is significantly reduced, so that the fault current that each breaking module needs to withstand and break is reduced, and the flexibility and safety of the equipment segmentation protection fault handling are improved.

Description

Technical Field

[0001] This invention relates to the field of segmented protection technology for electronic power systems, and in particular to a series oscillating circuit breaker graded interruption system, method, and storage medium. Background Technology

[0002] With the rapid development of flexible DC transmission, multi-terminal DC systems, and large-scale renewable energy integration, power systems are placing higher demands on their ability to quickly clear DC faults. Oscillating DC circuit breakers, due to their advantages such as low current loss, fast breaking speed, and low cost, have become a key area of ​​research and engineering application in DC breaking equipment in recent years. In existing technologies, oscillating DC circuit breakers typically consist of a current-carrying branch, an oscillating branch, and an energy-dissipating branch. The oscillating branch generates an oscillating current when a fault occurs, thus providing a zero-crossing arc-extinguishing condition for fast mechanical switching. The energy-dissipating branch absorbs residual energy in the system, limits overvoltage during the breaking process, and ensures safe equipment operation.

[0003] To accommodate higher voltage levels such as ±500kV and improve system reliability, multiple complete oscillating DC circuit breakers are typically connected in series within the system to share voltage load and isolate faults. Existing engineering solutions often employ a synchronous interruption strategy controlled by a higher-level system, where all circuit breakers connected in series synchronously interrupt upon receiving a fault signal from the higher-level control and protection system. However, this control strategy can lead to a significant time delay between the occurrence of a fault and the circuit breaker receiving the interruption command, particularly pronounced under fault conditions with high current rise rates. This results in each series-connected circuit breaker needing to withstand and interrupt a large fault current, significantly increasing the difficulty of interruption. Summary of the Invention

[0004] The present invention aims to provide a series oscillating circuit breaker graded interruption system, method and storage medium to avoid the series circuit breaker from bearing and interrupting large fault currents, reduce peak currents and improve the flexibility and safety of equipment sectional protection fault handling.

[0005] To achieve the above objectives, a first aspect of the present invention provides a series oscillating circuit breaker graded interruption system, comprising an oscillating circuit breaker circuit and an upper-level control module, wherein: The oscillating circuit breaker has several self-protected circuit breaker modules and several controlled circuit breaker modules connected in series between its input and output terminals. For any of the self-protection circuit breaking modules, when the self-protection circuit breaking module determines that the circuit current of the oscillating circuit breaking circuit exceeds the preset fault value, it performs a circuit breaking action to increase the impedance of the oscillating circuit breaking circuit, suppress the rise of the circuit current, and send a current fault signal to the upper-level control module. The upper-level control module responds to the current fault signal, determines that the oscillating circuit breaker generates a fault current, and then, after a preset delay, controls several controlled circuit breaker modules to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules, and thus completing the graded breaking of the fault current.

[0006] The aforementioned series-connected oscillating circuit breaker self-protection hierarchical interruption system, based on connecting multiple circuit breaker modules (i.e., circuit breakers) in series, incorporates a self-protecting circuit breaker module with local self-protection capabilities and a controlled circuit breaker module that awaits instructions from the upper-level control module. When the circuit current exceeds a preset fault value, the self-protecting circuit breaker module automatically initiates a circuit interruption locally, completing the primary circuit interruption by pre-increasing circuit impedance and suppressing the current rise rate and peak value. The upper-level control system, after confirming the generation of a fault current, then controls the controlled circuit breaker module to delay its circuit interruption, completing the secondary circuit interruption. In this case, the controlled circuit breaker module needs to interrupt a smaller current, significantly reducing its interruption burden and difficulty. Ultimately, this system achieves delayed hierarchical interruption for both types of circuit breaker modules. Compared to traditional synchronous interruption methods, its response time is significantly reduced, thereby lowering the fault current that each circuit breaker module needs to withstand and interrupt, improving the flexibility and safety of the equipment's segmented protection fault handling.

[0007] Furthermore, any of the self-protection circuit breaker modules includes a first switching unit, a first oscillating inductor, a first oscillating capacitor, a first oscillation unit, a first metal oxide rheostat, and a control unit; wherein: The first end of the first switch unit serves as the input end of the self-protection circuit breaker module, and the second end of the first switch unit serves as the output end of the self-protection circuit breaker module. One end of the first oscillating capacitor is electrically connected to the first end of the first switching unit, the other end of the first oscillating capacitor is electrically connected to one end of the first oscillating inductor, the other end of the first oscillating inductor is electrically connected to the input end of the first oscillating unit, and the output end of the first oscillating unit is electrically connected to the second end of the first switching unit. One end of the first metal oxide rheostat is electrically connected to the first end of the first switching unit, and the other end of the first metal oxide rheostat is electrically connected to the second end of the first switching unit. When the control unit determines that the circuit current of the oscillating circuit breaker exceeds the preset fault value, it controls the first switching unit to open and controls the first oscillating unit to generate oscillating current, thereby sending a current fault signal to the upper-level control module.

[0008] In this implementation, the first switching unit constitutes the current-carrying branch of the self-protected circuit breaker module, the first oscillating inductor, the first oscillating capacitor, and the first oscillating unit constitute the oscillation branch of the self-protected circuit breaker module, and the first metal oxide rheostat constitutes the energy-dissipating branch of the self-protected circuit breaker module.

[0009] When the control module detects that the current flowing through the current-carrying branch where the first switching unit is located exceeds a preset fault value, it triggers the control of the first switching unit to open, generating an arc on the first switching unit. At this time, the control module simultaneously controls the first oscillation unit to generate an oscillating current, which discharges through the first oscillating capacitor and the first oscillating inductor into the current-carrying branch. This causes the oscillating current to cancel out the fault current at a certain moment, creating a zero-crossing current condition in the current-carrying branch and extinguishing the arc. After the arc is extinguished, the fault current is completely transferred to the oscillating branch, causing the first oscillating capacitor to continue charging and its voltage to rise. When the voltage of the first oscillating capacitor rises to the operating threshold of the first metal oxide rheostat, i.e., the clamping voltage, the fault current is transferred to the energy-dissipating branch and consumed by the first metal oxide rheostat, completing the opening action of the self-protection circuit breaker module.

[0010] Furthermore, all of the self-protection circuit breaker modules also satisfy a first design rule, which includes: Obtain the clamping voltage of the first metal oxide rheostat in each of the self-protected circuit breaking modules; The sum of all the clamping voltages is taken as the total clamping voltage, which is less than the preset rated input voltage.

[0011] In this implementation, the circuit breaker module is divided into two types: one is a self-protection circuit breaker module with local self-protection function, which triggers circuit breaking based on a preset current fault value; the other is a controlled circuit breaker module that only breaks the circuit after receiving control commands from the upper-level control module. While the self-protection circuit breaker module can quickly respond to fault currents and break the circuit to prevent equipment damage, it is not controlled by the fault current detection and confirmation function of the upper-level control module and is therefore susceptible to fluctuations in normal circuit current values.

[0012] If the self-protection circuit breaker module malfunctions and triggers a disconnection action due to fluctuations in the normal circuit current value, it will cause the system to be impacted and downstream equipment to lose power. Furthermore, it will cause multiple metal oxide rheostats to lose a large amount of energy redundancy, resulting in the rheostats overheating and being unable to resume operation in a short period of time, increasing the risk of system failure.

[0013] Therefore, this implementation adopts the first design rule, controlling the number of self-protecting circuit breaker modules in the system within a certain range, so that the total clamping voltage is less than the preset rated input voltage. This design ensures that even if all self-protecting circuit breaker modules malfunction simultaneously due to interference and activate their energy-consuming branches, the total clamping voltage they generate is insufficient to offset the system power supply electromotive force. This allows the system current to avoid being forced to zero after a malfunction, and the current-carrying branch can maintain a non-zero current flow. This implementation avoids system power outages caused by malfunctions and can quickly restore the system to normal operation through automatic reclosing, minimizing the impact of local disturbances and significantly improving the system's robustness and safety.

[0014] Furthermore, any of the controlled circuit-breaking modules includes a second switching unit, a second oscillating inductor, a second oscillating capacitor, a second oscillation unit, a second metal-oxide rheostat, and a controlled unit; wherein: The first end of the second switch unit serves as the input end of the self-protection circuit breaker module, and the second end of the second switch unit serves as the output end of the self-protection circuit breaker module. One end of the second oscillating capacitor is electrically connected to the first end of the second switching unit, the other end of the second oscillating capacitor is electrically connected to one end of the second oscillating inductor, the other end of the second oscillating inductor is electrically connected to the input end of the second oscillating unit, and the output end of the second oscillating unit is electrically connected to the second end of the second switching unit. One end of the second metal oxide rheostat is electrically connected to the first end of the second switching unit, and the other end of the second metal oxide rheostat is electrically connected to the second end of the second switching unit. The controlled unit responds to the control command of the upper-level control module by controlling the second switching unit to open and controlling the second oscillation unit to generate oscillation current, thereby completing the graded interruption of fault current.

[0015] In this implementation, the second switching unit constitutes the current-carrying branch of the controlled circuit breaking module, the second oscillating inductor, the second oscillating capacitor and the second oscillating unit constitute the oscillation branch of the controlled circuit breaking module, and the second metal oxide rheostat constitutes the energy-dissipating branch of the controlled circuit breaking module.

[0016] When the upper-level control module receives a current fault signal and confirms that a fault current has indeed appeared in the current-carrying branch, and that it is not a normal current fluctuation, it controls the controlled module to perform an opening action after a certain delay after the self-protection circuit breaker module opens, completing the overall system-wide graded opening action. The controlled module triggers the control of the second switching unit to open, generating an arc on the second switching unit. At this time, the controlled module synchronously controls the second oscillation unit to generate an oscillating current, which discharges through the second oscillating capacitor and the second oscillating inductor into the current-carrying branch, so that the oscillating current cancels out the fault current at a certain moment, forming a current zero-crossing condition in the current-carrying branch, extinguishing the arc. After the arc is extinguished, the fault current is completely transferred to the oscillating branch, causing the second oscillating capacitor to continue charging, and the voltage of the second oscillating capacitor rises. When the voltage of the second oscillating capacitor rises to the action threshold of the second metal oxide rheostat, i.e., the clamping voltage, the fault current is transferred to the energy-dissipating branch and consumed by the second metal oxide rheostat, completing the opening action of the self-protection circuit breaker module.

[0017] Furthermore, for any of the self-protection circuit breaker modules, when the self-protection circuit breaker module determines that the circuit current of the oscillating circuit breaker exceeds a preset fault value, it performs a circuit breaking action to increase the impedance of the oscillating circuit breaker, suppress the rise of the circuit current, and sends a current fault signal to the upper-level control module, it further includes: If the upper-level control module does not determine that the oscillating circuit breaker generates a fault current within a preset time interval, the self-protection circuit breaker module will perform a circuit closing action.

[0018] In this implementation, after the self-protection circuit breaker module performs the circuit breaking action and sends a current fault signal to the upper-level control module, an additional false trip judgment time interval is introduced. If the upper-level control module does not determine that the oscillating circuit breaker circuit has generated a fault current within this time interval, it indicates that the current over-limit is a transient disturbance of the normal circuit current, rather than a fault current. At this time, the self-protection circuit breaker module performs the circuit closing action and quickly restores the system to normal operation through automatic reclosing, avoiding false tripping that could affect the normal operation of the system and downstream equipment, minimizing the impact of local disturbances, and significantly improving the robustness and safety of the system.

[0019] Furthermore, in response to the current fault signal, the upper-level control module determines that the oscillating circuit breaker generates a fault current. Then, after a preset delay, it controls several controlled circuit breaker modules to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules, thus completing the graded fault current breaking, including: In response to the current fault signal, it is determined that the oscillating circuit breaker generates a fault current. Then, after a preset delay, all the controlled circuit breaker modules are controlled to simultaneously perform circuit breaking actions, thereby increasing the circuit breaking action rate of the controlled circuit breaker modules and completing the graded breaking of the fault current.

[0020] In this implementation, in order to reduce the fault current that each circuit breaker module needs to withstand and interrupt by delay-level interruption of the two types of circuit breaker modules, thereby improving the flexibility and safety of fault handling of equipment segmented protection, the response speed of fault current interruption is improved. All the controlled circuit breaker modules are controlled to simultaneously and quickly interrupt the fault current, thereby suppressing the fault current to the maximum extent. Moreover, since the circuit impedance has been increased in advance during the primary circuit interruption, the rise rate and peak value of the circuit current are suppressed, thus ensuring the robustness and safety of the system.

[0021] A second aspect of the present invention provides a method for graded interruption of a series resonant circuit breaker, applicable to the self-protected graded interruption system of a series resonant circuit breaker as described in any one of the first aspects of the present invention. The method includes the following steps: For any of the self-protection circuit breaking modules, when it is determined that the circuit current of the oscillating circuit breaking circuit exceeds the preset fault value, a circuit breaking action is performed to increase the impedance of the oscillating circuit breaking circuit, suppress the rise of the circuit current, and detect the fault current of the oscillating circuit breaking circuit. The fault current generated by the oscillating circuit is determined, and then after a preset delay, several controlled circuit breaking modules are controlled to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaking modules, and thus completing the graded breaking of the fault current.

[0022] In this implementation, when the circuit current exceeds a preset fault value, the self-protection circuit breaker module can first automatically initiate a circuit interruption locally, completing the primary circuit interruption and pre-increasing the circuit impedance to suppress the rise rate and peak value of the circuit current. The upper-level control system, after detecting and confirming that a fault current has indeed been generated in the circuit, then controls the controlled circuit breaker module to delay its circuit interruption, completing the secondary circuit interruption. At this point, the current value that the controlled circuit breaker module needs to interrupt is reduced, significantly lowering its interruption burden and difficulty. Ultimately, this system achieves delayed, graded interruption for two types of circuit breaker modules. Compared to the traditional synchronous interruption method, its action response time is significantly reduced, thereby reducing the fault current that each circuit breaker module needs to withstand and interrupt, improving the flexibility and safety of the equipment's segmented protection fault handling.

[0023] Furthermore, after determining that the circuit current of the oscillating circuit breaker exceeds a preset fault value for any of the self-protection circuit breaker modules, performing a circuit breaking action to increase the impedance of the oscillating circuit breaker, suppressing the rise of the circuit current, and detecting the fault current of the oscillating circuit breaker, the method further includes: If the oscillating circuit does not generate a fault current within a preset time interval, the self-protection circuit breaker module is controlled to close the circuit.

[0024] In this implementation, after the self-protection circuit breaker module performs the circuit breaking action and sends a current fault signal to the upper-level control module, an additional false trip judgment time interval is introduced. If the upper-level control module does not determine that the oscillating circuit breaker circuit has generated a fault current within this time interval, it indicates that the current over-limit is a transient disturbance of the normal circuit current, rather than a fault current. At this time, the self-protection circuit breaker module performs the circuit closing action and quickly restores the system to normal operation through automatic reclosing, avoiding false tripping that could affect the normal operation of the system and downstream equipment, minimizing the impact of local disturbances, and significantly improving the robustness and safety of the system.

[0025] Furthermore, the step of determining that the oscillating circuit breaker generates a fault current, and then, after a preset delay, controlling several controlled circuit breaker modules to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules, and thus completing the graded breaking of the fault current, includes: The fault current is determined to be generated by the oscillating circuit breaking circuit. Then, after a preset delay, all the controlled circuit breaking modules are controlled to simultaneously perform circuit breaking actions, thereby increasing the circuit breaking action rate of the controlled circuit breaking modules and completing the graded breaking of the fault current.

[0026] In this implementation, in order to reduce the fault current that each circuit breaker module needs to withstand and interrupt by delay-level interruption of the two types of circuit breaker modules, thereby improving the flexibility and safety of fault handling of equipment segmented protection, the response speed of fault current interruption is improved. All the controlled circuit breaker modules are controlled to simultaneously and quickly interrupt the fault current, thereby suppressing the fault current to the maximum extent. Moreover, since the circuit impedance has been increased in advance during the primary circuit interruption, the rise rate and peak value of the circuit current are suppressed, thus ensuring the robustness and safety of the system.

[0027] A third aspect of the present invention provides a computer-readable storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device in which the computer storage medium is located to perform a series oscillating circuit breaker graded interruption method as described in any of the second aspects of the present invention. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a series oscillating circuit breaker graded interruption system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of another series oscillating circuit breaker graded interruption system provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the fault current change during the operation of an oscillating circuit breaking circuit provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of voltage changes during the operation of an oscillating circuit breaking circuit provided in an embodiment of the present invention; Figure 5 This is a schematic flowchart of a series oscillating circuit breaker graded interruption method provided in an embodiment of the present invention; Among them: 100, oscillating circuit breaker; 110, self-protected circuit breaker module; 111, control unit; 112, first oscillation unit; 120, controlled circuit breaker module; 121, response unit; 122, second oscillation unit; 200, upper-level control module; S1, first switching unit; S2, second switching unit; C1, first oscillation capacitor; C2, second oscillation capacitor; L1, first oscillation inductor; L2, second oscillation inductor; MOV1, first metal oxide rheostat; MOV2, second metal oxide rheostat; MMC, modular multilevel converter. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following detailed descriptions are exemplary and intended to provide further detailed explanation of the invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein in the specification is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms "comprising" and "having," and any variations thereof, in the specification, claims, and foregoing drawings, are intended to cover non-exclusive inclusion. The terms "first," "second," etc., in the specification, claims, or foregoing drawings are used to distinguish different objects, not to describe a particular order.

[0030] It should be understood that although the steps in the flowcharts of the accompanying figures are shown sequentially as indicated by the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the accompanying figures may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily completed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the sub-steps or stages of other steps.

[0031] This invention proposes a self-protection hierarchical interruption method for multiple series-connected complete oscillating DC circuit breakers, enabling each circuit breaker in series to have self-protection and self-identification capabilities. Before the main control system sends a signal, some circuit breakers are allowed to automatically operate, which can effectively reduce the maximum value of the fault current, thereby improving the flexibility and safety of the system fault handling.

[0032] Please refer to Figure 1 To achieve the above objectives, the first embodiment of the present invention provides a series oscillating circuit breaker graded interruption system, including an oscillating circuit breaker circuit 100 and an upper-level control module 200, wherein: The oscillating circuit breaker 100 has several self-protection circuit breaker modules 110 and several controlled circuit breaker modules 120 connected in series between its input and output terminals. For any of the self-protection circuit breaker modules 110, when the self-protection circuit breaker module 110 determines that the circuit current of the oscillating circuit breaker 100 exceeds the preset fault value, it performs a circuit breaking action to increase the impedance of the oscillating circuit breaker 100, suppress the rise of the circuit current, and send a current fault signal to the upper-level control module 200. The upper-level control module 200 responds to the current fault signal, determines that the oscillating circuit breaker 100 generates a fault current, and then, after a preset delay, controls several controlled circuit breaker modules 120 to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules 120, and thus completing the graded breaking of the fault current.

[0033] The aforementioned series-connected oscillating circuit breaker self-protection hierarchical interruption system, based on connecting multiple circuit breaker modules (i.e., circuit breakers) in series, incorporates a self-protection circuit breaker module 110 with local self-protection capabilities and a controlled circuit breaker module 120 that awaits instructions from the upper-level control module 200. When the circuit current exceeds a preset fault value, the self-protection circuit breaker module 110 automatically initiates a circuit interruption locally, completing the primary circuit interruption and pre-increasing circuit impedance to suppress the current rise rate and peak value. The upper-level control system, after detecting and confirming the generation of a fault current, then controls the controlled circuit breaker module 120 to delay its circuit interruption, completing the secondary circuit interruption. In this case, the current value that the controlled circuit breaker module 120 needs to interrupt is reduced, significantly lowering its interruption burden and difficulty. Ultimately, this system achieves delayed hierarchical interruption for both types of circuit breaker modules. Compared to traditional synchronous interruption methods, its response time is significantly reduced, thereby lowering the fault current that each circuit breaker module needs to withstand and interrupt, improving the flexibility and safety of the equipment's segmented protection fault handling.

[0034] Please refer to Figure 2 Furthermore, any of the self-protection circuit breaker modules 110 includes a first switching unit S1, a first oscillating inductor L1, a first oscillating capacitor C1, a first oscillation unit 112, a first metal oxide rheostat MOV1, and a control unit 111; wherein: The first end of the first switch unit S1 serves as the input end of the self-protection circuit breaker module 110, and the second end of the first switch unit S1 serves as the output end of the self-protection circuit breaker module 110. One end of the first oscillating capacitor C1 is electrically connected to the first end of the first switching unit S1, the other end of the first oscillating capacitor C1 is electrically connected to one end of the first oscillating inductor L1, the other end of the first oscillating inductor L1 is electrically connected to the input end of the first oscillating unit 112, and the output end of the first oscillating unit 112 is electrically connected to the second end of the first switching unit S1. One end of the first metal oxide rheostat MOV1 is electrically connected to the first end of the first switching unit S1, and the other end of the first metal oxide rheostat MOV1 is electrically connected to the second end of the first switching unit S1. When the control unit 111 determines that the circuit current of the oscillating circuit breaker 100 exceeds the preset fault value, it controls the first switching unit S1 to open and controls the first oscillating unit 112 to generate oscillating current, thereby sending a current fault signal to the upper-level control module 200.

[0035] In this embodiment, the first switching unit S1 constitutes the current-carrying branch of the self-protected circuit breaker module 110, the first oscillating inductor L1, the first oscillating capacitor C1 and the first oscillating unit 112 constitute the oscillation branch of the self-protected circuit breaker module 110, and the first metal oxide rheostat MOV1 constitutes the energy-dissipating branch of the self-protected circuit breaker module 110.

[0036] When the control module detects that the current flowing through the current-carrying branch where the first switching unit S1 is located exceeds a preset fault value, it triggers the control to open the first switching unit S1, generating an arc on the first switching unit S1. At this time, the control module synchronously controls the first oscillation unit 112 to generate an oscillating current, which discharges through the first oscillating capacitor C1 and the first oscillating inductor L1 into the current-carrying branch. This causes the oscillating current to cancel out the fault current at a certain moment, creating a zero-crossing current condition in the current-carrying branch and extinguishing the arc. After the arc is extinguished, the fault current is completely transferred to the oscillating branch, causing the first oscillating capacitor C1 to continue charging and its voltage to rise. When the voltage of the first oscillating capacitor C1 rises to the operating threshold of the first metal oxide rheostat MOV1, i.e., the clamping voltage, the fault current is transferred to the energy-dissipating branch and consumed by the first metal oxide rheostat MOV1, completing the opening action of the self-protection circuit breaker module 110.

[0037] Furthermore, all of the self-protection circuit breaker modules 110 also satisfy a first design rule, which includes: Obtain the clamping voltage of the first metal oxide rheostat MOV1 in each of the self-protection circuit breaking modules 110; The sum of all the clamping voltages is taken as the total clamping voltage, which is less than the preset rated input voltage.

[0038] In this embodiment, the circuit breaker module is divided into two types: one is a self-protection circuit breaker module 110 with local self-protection function, which triggers circuit breaking based on a preset current fault value; the other is a controlled circuit breaker module 120 that only breaks the circuit after receiving a control command from the upper-level control module 200. Although the self-protection circuit breaker module 110 can quickly respond to the fault current to break the circuit and prevent equipment damage, it is not controlled by the fault current detection and confirmation function of the upper-level control module 200, and is therefore susceptible to fluctuations in the normal circuit current value.

[0039] If the self-protection circuit breaker module 110 is malfunctioning due to fluctuations in the normal circuit current, it will cause the system to be impacted and downstream equipment to lose power. Furthermore, it will cause multiple metal oxide rheostats to lose a large amount of energy redundancy, resulting in the rheostats overheating and being unable to resume operation in a short period of time, increasing the risk of system failure.

[0040] Therefore, this embodiment adopts the first design rule, controlling the number of self-protecting circuit breaker modules 110 in the system within a certain range, so that the total clamping voltage is less than the preset rated input voltage. This design ensures that even if all self-protecting circuit breaker modules 110 malfunction simultaneously due to interference and engage their energy-consuming branches, the total clamping voltage they generate is insufficient to offset the system power supply electromotive force. This allows the system current to remain within zero after a malfunction, maintaining a non-zero current flow in the current-carrying branch. This embodiment avoids system power outages caused by malfunctions and can quickly restore the system to normal operation through automatic reclosing, minimizing the impact of local disturbances and significantly improving the system's robustness and safety.

[0041] Please refer to Figure 2 Furthermore, any of the controlled circuit breaker modules 120 includes a second switching unit S2, a second oscillating inductor L2, a second oscillating capacitor C2, a second oscillation unit 122, a second metal oxide rheostat MOV2, and a controlled unit; wherein: The first end of the second switch unit S2 serves as the input end of the self-protection circuit breaker module 110, and the second end of the second switch unit S2 serves as the output end of the self-protection circuit breaker module 110. One end of the second oscillating capacitor C2 is electrically connected to the first end of the second switching unit S2, the other end of the second oscillating capacitor C2 is electrically connected to one end of the second oscillating inductor L2, the other end of the second oscillating inductor L2 is electrically connected to the input end of the second oscillating unit 122, and the output end of the second oscillating unit 122 is electrically connected to the second end of the second switching unit S2. One end of the second metal oxide rheostat MOV2 is electrically connected to the first end of the second switching unit S2, and the other end of the second metal oxide rheostat MOV2 is electrically connected to the second end of the second switching unit S2. The controlled unit responds to the control command of the upper-level control module 200 by controlling the second switch unit S2 to open and controlling the second oscillation unit 122 to generate oscillation current, thereby completing the graded interruption of fault current.

[0042] In this embodiment, the second switching unit S2 constitutes the current-carrying branch of the controlled circuit breaking module 120, the second oscillating inductor L2, the second oscillating capacitor C2 and the second oscillating unit 122 constitute the oscillation branch of the controlled circuit breaking module 120, and the second metal oxide rheostat MOV2 constitutes the energy-dissipating branch of the controlled circuit breaking module 120.

[0043] When the upper-level control module 200 receives a current fault signal and confirms that a fault current has indeed appeared in the current-carrying branch, and that it is not a normal current fluctuation, it controls the controlled module to perform an opening action after a certain delay after the self-protection circuit breaker module 110 opens, completing the overall system-wide graded opening and closing. The controlled module triggers the control of the second switch unit S2 to open, generating an arc on the second switch unit S2. At this time, the controlled module synchronously controls the second oscillation unit 122 to generate an oscillating current, which discharges through the second oscillating capacitor C2 and the second oscillating inductor L2 into the current-carrying branch, so that the oscillating current cancels out the fault current at a certain moment, forming a current zero-crossing condition in the current-carrying branch, extinguishing the arc. After the arc is extinguished, the fault current is completely transferred to the oscillating branch, causing the second oscillating capacitor C2 to continue charging, and the voltage of the second oscillating capacitor C2 rises. When the voltage of the second oscillating capacitor C2 rises to the operating threshold of the second metal oxide rheostat MOV2, i.e. the clamping voltage, the fault current is transferred to the energy-consuming branch and consumed by the second metal oxide rheostat MOV2, thus completing the opening action of the self-protection circuit breaker module 110.

[0044] Furthermore, for any of the self-protection circuit breaker modules 110, when the self-protection circuit breaker module 110 determines that the circuit current of the oscillating circuit breaker circuit 100 exceeds a preset fault value, it performs a circuit breaking action to increase the impedance of the oscillating circuit breaker circuit 100, suppress the rise of the circuit current, and sends a current fault signal to the upper-level control module 200, it further includes: If the upper-level control module 200 does not determine that the oscillating circuit breaker 100 generates a fault current within a preset time interval, the self-protection circuit breaker module 110 performs a circuit closing action.

[0045] In this embodiment, after the self-protection circuit breaker module 110 performs a circuit breaking action and sends a current fault signal to the upper-level control module 200, an additional false trip judgment time interval is introduced. If the upper-level control module 200 does not determine that the oscillating circuit breaker 100 has generated a fault current within this time interval, it indicates that the current over-limit is a transient disturbance of the normal circuit current, rather than a fault current. At this time, the self-protection circuit breaker module 110 performs a circuit closing action, and quickly restores the system to normal operation through automatic reclosing, avoiding the impact of false trips on the normal operation of the system and downstream equipment, minimizing the impact of local disturbances, and significantly improving the robustness and safety of the system.

[0046] Furthermore, in response to the current fault signal, the upper-level control module 200 determines that the oscillating circuit breaker 100 has generated a fault current. Then, after a preset delay, it controls several controlled circuit breaker modules 120 to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules 120, thus completing the graded fault current breaking, including: In response to the current fault signal, it is determined that the oscillating circuit breaker 100 generates a fault current. Then, after a preset delay, all the controlled circuit breaker modules 120 are controlled to simultaneously perform circuit breaking actions, thereby increasing the circuit breaking action rate of the controlled circuit breaker modules 120 and completing the graded breaking of the fault current.

[0047] In this embodiment, in order to reduce the fault current that each circuit breaker module needs to withstand and interrupt by delay-level interruption of the two types of circuit breaker modules, improve the flexibility and safety of fault handling of equipment segmented protection, and improve the response speed of fault current interruption, all the controlled circuit breaker modules 120 are controlled to simultaneously and quickly interrupt, thereby suppressing the fault current to the maximum extent; and since the circuit impedance has been increased in advance for the primary circuit interruption, the rise rate and peak value of the circuit current are suppressed, thus ensuring the robustness and safety of the system.

[0048] Please refer to Figure 5 The second embodiment of the present invention provides a method for graded interruption of a series resonant circuit breaker, applicable to the self-protected graded interruption system of a series resonant circuit breaker as described in any of the first aspects of the present invention. The method includes the following steps: S1. For any of the self-protection circuit breaker modules 110, when it is determined that the circuit current of the oscillating circuit breaker 100 exceeds the preset fault value, a circuit breaking action is performed to increase the impedance of the oscillating circuit breaker 100, suppress the rise of the circuit current, and detect the fault current of the oscillating circuit breaker 100. S2. Determine that the oscillating circuit breaker 100 generates a fault current, and then after a preset delay, control several controlled circuit breaker modules 120 to perform circuit breaking actions, thereby reducing the fault current broken by several controlled circuit breaker modules 120, and thus completing the graded breaking of the fault current.

[0049] In this embodiment, when the circuit current exceeds a preset fault value, the self-protection circuit breaker module 110 can first automatically perform a circuit breaking action locally, completing the primary circuit breaking, pre-increasing the circuit impedance, and suppressing the rise rate and peak value of the circuit current. After the upper-level control system detects and confirms that a fault current has indeed been generated in the circuit, it then controls the controlled circuit breaker module 120 to delay its circuit breaking action, completing the secondary circuit breaking. At this time, the current value that the controlled circuit breaker module 120 needs to break is reduced, and its breaking burden and difficulty are significantly reduced. Ultimately, this system achieves delayed, graded breaking of two types of circuit breakers. Compared with the traditional synchronous breaking method, its action response time is significantly reduced, thereby reducing the fault current that each circuit breaker module needs to withstand and break, and improving the flexibility and safety of the equipment's segmented protection fault handling.

[0050] Furthermore, after determining that the circuit current of the oscillating circuit breaker 100 exceeds a preset fault value for any of the self-protection circuit breaker modules 110, the circuit is interrupted to increase the impedance of the oscillating circuit breaker 100, suppress the rise of the circuit current, and the fault current of the oscillating circuit breaker 100 is detected, the method further includes: If the oscillating circuit breaker 100 does not generate a fault current within a preset time interval, the self-protection circuit breaker module 110 is controlled to perform a circuit closing action.

[0051] In this embodiment, after the self-protection circuit breaker module 110 performs a circuit breaking action and sends a current fault signal to the upper-level control module 200, an additional false trip judgment time interval is introduced. If the upper-level control module 200 does not determine that the oscillating circuit breaker 100 has generated a fault current within this time interval, it indicates that the current over-limit is a transient disturbance of the normal circuit current, rather than a fault current. At this time, the self-protection circuit breaker module 110 performs a circuit closing action, and quickly restores the system to normal operation through automatic reclosing, avoiding the impact of false trips on the normal operation of the system and downstream equipment, minimizing the impact of local disturbances, and significantly improving the robustness and safety of the system.

[0052] Further, the step of determining that the oscillating circuit breaker 100 generates a fault current, and then, after a preset delay, controlling several controlled circuit breaker modules 120 to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules 120, and thus completing the graded breaking of the fault current, includes: Once it is determined that the oscillating circuit breaker 100 generates a fault current, after a preset delay, all the controlled circuit breaker modules 120 are controlled to simultaneously perform circuit breaking actions, thereby increasing the circuit breaking action rate of the controlled circuit breaker modules 120 and completing the graded breaking of the fault current.

[0053] In this embodiment, in order to reduce the fault current that each circuit breaker module needs to withstand and interrupt by delay-level interruption of the two types of circuit breaker modules, improve the flexibility and safety of fault handling of equipment segmented protection, and improve the response speed of fault current interruption, all the controlled circuit breaker modules 120 are controlled to simultaneously and quickly interrupt, thereby suppressing the fault current to the maximum extent; and since the circuit impedance has been increased in advance for the primary circuit interruption, the rise rate and peak value of the circuit current are suppressed, thus ensuring the robustness and safety of the system.

[0054] Please refer to this as well. Figure 2 , Figure 3 and Figure 4 In one specific embodiment, wherein Figure 2 This is a schematic diagram of a series oscillating circuit breaker graded interruption system; Figure 3 This is a schematic diagram of the fault current change during the operation of an oscillating circuit breaker 100 provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of voltage changes during the operation of an oscillating circuit breaker 100 provided in an embodiment of the present invention.

[0055] In this embodiment, the oscillating circuit breaker 100 includes a modular multilevel converter (MMC); the input terminal of the modular multilevel converter (MMC) serves as the input terminal of the oscillating circuit breaker 100, and a self-protected circuit breaker module 110 and two controlled circuit breaker modules 120 are connected in series between the output terminal of the modular multilevel converter (MMC) and the output terminal of the oscillating circuit breaker 100. The multilevel converter is used to convert the AC input voltage on the AC side into a DC voltage.

[0056] In this embodiment, at time t0 when the fault current of the oscillating circuit breaker 100 is generated, the fault current begins to rise rapidly; at time t1, the control unit 111 of the self-protection circuit breaker module 110 detects that the fault current has reached its self-protection action current threshold, triggers the opening action of the first switching unit S1, and simultaneously controls the first oscillation unit 112 to start generating zero-crossing conditions, and feeds back the current information to the upper-level control module 200 through the status communication interface for fault identification.

[0057] Subsequently, at time t2, the upper-level control module 200 completes fault identification and sends disconnection commands to the two controlled circuit breaker modules 120, initiating their tripping operations. To address potential maloperations caused by system disturbances, the self-protected circuit breaker module 110 is equipped with a reclosing control strategy: if the upper-level control module 200 fails to send a disconnection command to the controlled circuit breaker module 120 within the preset waiting time interval, it is determined to be a maloperation, and the self-protected circuit breaker module 110 will automatically perform a reclosing operation.

[0058] After the inherent cutoff time of the self-protection circuit breaker module 110, at time t3, the voltage of the first oscillating capacitor C1 in the oscillating branch of the self-protection circuit breaker module 110 rises to the action threshold of the first metal oxide rheostat MOV1, the current is transferred to the energy-consuming branch, the first metal oxide rheostat MOV1 begins to absorb energy, thereby completing the disconnection action, and the fault current no longer continues to rise.

[0059] Meanwhile, after the inherent cut-off time of the two controlled circuit breaking modules 120, at time t4, both controlled modules complete the current transfer, the fault current gradually decreases, and at time t5, the fault current is completely interrupted.

[0060] like Figure 3 As shown, after adopting the graded interruption strategy of the present invention, the maximum value of the fault current is significantly lower than that of the prior art using the upper-level control synchronous interruption strategy. This reflects the response difference of different levels of protection. The delay between t1 and t2 reflects that the rapid action of the self-protection circuit breaker module 110 based on the local current threshold belongs to the equipment-level autonomous protection, while the upper-level control module 200 needs to perform inter-station communication and collaborative judgment, so that the controlled circuit breaker module 120 interrupts after the self-protection circuit breaker module 110 with a delay, which effectively reduces the peak value of the fault current and improves the system stability.

[0061] Furthermore, in this embodiment, the circuit breaker modules are configured in two different types to achieve coordinated protection: one type of circuit breaker module has a local self-protection function and can autonomously initiate a tripping operation when the fault current reaches its self-protection action threshold; the other type of circuit breaker module operates according to the instructions of the upper-level control and protection system. Therefore, by controlling the controlled circuit breaker module 120 to coordinate and quickly trip after receiving the tripping command, the rise of the fault current is suppressed to the maximum extent. If all circuit breaker modules in the system adopt the self-protection circuit breaker module 110 mode, then in the event of a malfunction, all circuit breakers need to perform a reclosing operation. This will not only cause a significant impact on the system, but also cause the parallel surge arrester energy absorption elements to dissipate a large amount of energy, causing them to lose the necessary energy redundancy. This results in the circuit breaker losing its ability to re-interrupt due to insufficient heat dissipation of the surge arrester in a short period of time, thus significantly increasing the risk of failure.

[0062] Therefore, in a series system containing a larger number of circuit breakers, the specific configuration quantity of the above two types of circuit breakers can be optimized and determined according to the system's tolerance to current surges and transient processes. This ensures that if any self-protected circuit breaker module 110 malfunctions and does not cause the system current to cross zero during the period before performing reclosing operations, thereby ensuring the continuity and reliability of system operation. In other words, the number of self-protected circuit breaker modules 110 in the system is controlled within a certain range, so that the total clamping voltage is less than the preset rated input voltage.

[0063] This design rule avoids system power outages caused by malfunctions and can quickly restore the system to normal operation through automatic reclosing, minimizing the impact of local disturbances and significantly improving the system's robustness and safety.

[0064] A third embodiment of the present invention provides a computer-readable storage medium comprising a stored computer program, wherein, when the computer program is executed, it controls the device where the computer storage medium is located to perform a series oscillating circuit breaker graded interruption method as described in any of the second aspects of the present invention.

[0065] Those skilled in the art will understand that all or part of the processes in the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments described above. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.

[0066] The term "embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; however, any combination of these technical features that does not contradict each other should be considered within the scope of this specification.

[0067] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the concept of this application, and these improvements and substitutions should also be considered within the scope of protection of this invention. Therefore, the scope of protection of this application should be determined by the appended claims.

Claims

1. A series oscillating circuit breaker graded interruption system, characterized in that, Includes an oscillating circuit breaker and an upstream control module, wherein: The oscillating circuit breaker has several self-protected circuit breaker modules and several controlled circuit breaker modules connected in series between its input and output terminals. For any of the self-protection circuit breaking modules, when the self-protection circuit breaking module determines that the circuit current of the oscillating circuit breaking circuit exceeds the preset fault value, it performs a circuit breaking action to increase the impedance of the oscillating circuit breaking circuit, suppress the rise of the circuit current, and send a current fault signal to the upper-level control module. The upper-level control module responds to the current fault signal, determines that the oscillating circuit breaker generates a fault current, and then, after a preset delay, controls several controlled circuit breaker modules to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules, and thus completing the graded breaking of the fault current.

2. The series oscillating circuit breaker graded interruption system according to claim 1, characterized in that, For any of the self-protection circuit breaking modules, there are a first switching unit, a first oscillating inductor, a first oscillating capacitor, a first oscillation unit, a first metal oxide rheostat, and a control unit; wherein: The first end of the first switch unit serves as the input end of the self-protection circuit breaker module, and the second end of the first switch unit serves as the output end of the self-protection circuit breaker module. One end of the first oscillating capacitor is electrically connected to the first end of the first switching unit, the other end of the first oscillating capacitor is electrically connected to one end of the first oscillating inductor, the other end of the first oscillating inductor is electrically connected to the input end of the first oscillating unit, and the output end of the first oscillating unit is electrically connected to the second end of the first switching unit. One end of the first metal oxide rheostat is electrically connected to the first end of the first switching unit, and the other end of the first metal oxide rheostat is electrically connected to the second end of the first switching unit. When the control unit determines that the circuit current of the oscillating circuit breaker exceeds the preset fault value, it controls the first switching unit to open and controls the first oscillating unit to generate oscillating current, thereby sending a current fault signal to the upper-level control module.

3. A series oscillating circuit breaker graded interruption system according to claim 2, characterized in that, All of the self-protection circuit breaker modules also satisfy a first design rule, which includes: Obtain the clamping voltage of the first metal oxide rheostat in each of the self-protected circuit breaking modules; The sum of all the clamping voltages is taken as the total clamping voltage, which is less than the preset rated input voltage.

4. The series oscillating circuit breaker graded interruption system according to claim 1, characterized in that, For any of the controlled circuit breaking modules, there are a second switching unit, a second oscillating inductor, a second oscillating capacitor, a second oscillation unit, a second metal oxide rheostat, and a controlled unit; wherein: The first end of the second switch unit serves as the input end of the self-protection circuit breaker module, and the second end of the second switch unit serves as the output end of the self-protection circuit breaker module. One end of the second oscillating capacitor is electrically connected to the first end of the second switching unit, the other end of the second oscillating capacitor is electrically connected to one end of the second oscillating inductor, the other end of the second oscillating inductor is electrically connected to the input end of the second oscillating unit, and the output end of the second oscillating unit is electrically connected to the second end of the second switching unit. One end of the second metal oxide rheostat is electrically connected to the first end of the second switching unit, and the other end of the second metal oxide rheostat is electrically connected to the second end of the second switching unit. The controlled unit responds to the control command of the upper-level control module by controlling the second switching unit to open and controlling the second oscillation unit to generate oscillation current, thereby completing the graded interruption of fault current.

5. A series oscillating circuit breaker graded interruption system according to claim 1, characterized in that, For any of the self-protection circuit breaking modules, when the self-protection circuit breaking module determines that the circuit current of the oscillating circuit breaking circuit exceeds a preset fault value, it performs a circuit breaking action to increase the impedance of the oscillating circuit breaking circuit, suppress the rise of the circuit current, and sends a current fault signal to the upper-level control module, it further includes: If the upper-level control module does not determine that the oscillating circuit breaker generates a fault current within a preset time interval, the self-protection circuit breaker module will perform a circuit closing action.

6. A series oscillating circuit breaker graded interruption system according to claim 1, characterized in that, The upper-level control module responds to the current fault signal, determines that the oscillating circuit breaker generates a fault current, and then, after a preset delay, controls several controlled circuit breaker modules to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaker modules, and thus completing the graded fault current breaking, including: In response to the current fault signal, it is determined that the oscillating circuit breaker generates a fault current. Then, after a preset delay, all the controlled circuit breaker modules are controlled to simultaneously perform circuit breaking actions, thereby increasing the circuit breaking action rate of the controlled circuit breaker modules and completing the graded breaking of the fault current.

7. A method for graded interruption of a series oscillating circuit breaker, characterized in that, The method applicable to the series oscillating circuit breaker self-protection graded interruption system according to any one of claims 1 to 6 includes the following steps: For any of the self-protection circuit breaking modules, when it is determined that the circuit current of the oscillating circuit breaking circuit exceeds the preset fault value, a circuit breaking action is performed to increase the impedance of the oscillating circuit breaking circuit, suppress the rise of the circuit current, and detect the fault current of the oscillating circuit breaking circuit. The fault current generated by the oscillating circuit is determined, and then after a preset delay, several controlled circuit breaking modules are controlled to perform circuit breaking actions, thereby reducing the fault current broken by the several controlled circuit breaking modules, and thus completing the graded breaking of the fault current.

8. The method for graded interruption of a series oscillating circuit breaker according to claim 7, characterized in that, The method further includes, for any of the self-protection circuit breaking modules, determining that when the circuit current of the oscillating circuit breaking circuit exceeds a preset fault value, performing a circuit breaking action to increase the impedance of the oscillating circuit breaking circuit, suppressing the rise of the circuit current, and detecting the fault current of the oscillating circuit breaking circuit, as well as: If the oscillating circuit does not generate a fault current within a preset time interval, the self-protection circuit breaker module is controlled to close the circuit.

9. A method for graded interruption of a series oscillating circuit breaker according to claim 7, characterized in that, The process involves determining that the oscillating circuit breaks generate a fault current, and then, after a preset delay, controlling several controlled circuit breaking modules to perform circuit breaking actions. This reduces the fault current interrupted by the several controlled circuit breaking modules, thereby completing the graded interruption of the fault current. The fault current is determined to be generated by the oscillating circuit breaking circuit. Then, after a preset delay, all the controlled circuit breaking modules are controlled to simultaneously perform circuit breaking actions, thereby increasing the circuit breaking action rate of the controlled circuit breaking modules and completing the graded breaking of the fault current.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device on which the computer storage medium is located to perform the series oscillating circuit breaker graded interruption method as described in any one of claims 7 to 9.

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