Method and device for suppressing asymmetric short-circuit current

Abstract

The invention discloses a method and a device for suppressing asymmetric short-circuit current. The relay protection device is controlled to send time sequence control signals to the phase control vacuum circuit breaker and the high-voltage SF6 circuit breaker, and the high-voltage SF6 circuit breaker cuts off current at a first zero crossing point after opening and arcing according to the signals. Meanwhile, a phase control device of the phase control vacuum circuit breaker predicts a second zero crossing point according to the signal, and the current is cut off at the point. According to the invention, the advantages of the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker are combined, the action time sequence is optimized, the switching-on and switching-off strategy is matched, the asymmetric short-circuit current is efficiently suppressed, and the reliability and the safety of a power system are improved.

Description

Technical Field

[0001] The present invention relates to the field of suppressing asymmetric short-circuit current, and in particular to a method and a device for suppressing asymmetric short-circuit current. Background Art

[0002] With the continuous expansion of my country's power grid, the complexity and capacity of the power system are also increasing significantly, and the short-circuit current is rising rapidly. In order to limit the excessive AC component, high-impedance transformers and current-limiting reactors are used in large quantities, resulting in an increase in the decay time constant of the DC component in the short-circuit current. In addition, due to the problem of excessive short-circuit current in power supply and load-intensive areas, the hidden danger of insufficient circuit breaker breaking capacity has become increasingly prominent, becoming an unavoidable major technical and economic issue in the development of contemporary power grids.

[0003] Asymmetric short-circuit current will increase the difficulty of breaking, the arc will be difficult to extinguish, the arc will burn for a longer time, resulting in more serious arc burning, damage to the contacts and insulation structure of the circuit breaker, shortening the life of the equipment, and placing higher requirements on the breaking performance of the circuit breaker.

[0004] Traditional circuit breakers often have problems such as slow response, incomplete breaking, and severe equipment wear when dealing with asymmetric short-circuit faults in large-scale power grids. Phase-controlled vacuum circuit breakers have high-speed and high-precision breaking capabilities, can respond quickly and break current in a shorter arcing time. High-voltage SF6 circuit breakers have higher breaking capabilities and stronger insulation performance, and can provide stable and reliable protection under high voltage and high current conditions. The vacuum medium recovers quickly, but the vacuum gap breakdown voltage has a saturation effect as the vacuum gap increases, and the insulation strength is low. SF6 has high insulation strength, but the medium recovers slowly. Both have superior performance, but when used alone, they still cannot fully cope with the increasingly complex short-circuit conditions in modern power systems.

[0005] Therefore, there is an urgent need for a new solution that can combine the advantages of phase-controlled vacuum circuit breakers and high-voltage SF6 circuit breakers, optimize their action timing and coordinated breaking strategies, achieve efficient suppression of asymmetric short-circuit currents, and improve the reliability and safety of the power system. Summary of the invention

[0006] The present invention provides a method and a device for suppressing an asymmetric short-circuit current, so as to solve the problem that the asymmetric short-circuit current cannot be efficiently suppressed in the prior art.

[0007] In a first aspect, the present application provides a method for suppressing asymmetric short-circuit current, comprising:

[0008] Controlling the relay protection device to send a timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively; wherein the timing control signal is generated by the relay protection device of the power system when a short circuit fault is detected;

[0009] So that the high-voltage SF6 circuit breaker breaks the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal;

[0010] The phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current according to the timing control signal to obtain a second zero-crossing point; the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0011] The present application ensures a rapid response to a short-circuit fault by quickly detecting and issuing a timing control signal through a relay protection device; the phase-controlled device of the phase-controlled vacuum circuit breaker determines the optimal zero-crossing breaking moment through an intelligent prediction algorithm, which can improve the accuracy and synchronization of the breaking, and cooperates with the high-voltage SF6 circuit breaker. The two circuit breakers cooperate to break at the same zero-crossing point, thereby achieving efficient suppression of the short-circuit current, so as to solve the problem that the prior art cannot achieve efficient suppression of asymmetric short-circuit current.

[0012] As a preferred embodiment of the first aspect, the high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal, and further includes:

[0013] If the high-voltage SF6 circuit breaker fails to interrupt the short-circuit current at the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0014] In this preferred embodiment, the present application provides a double insurance mechanism to ensure that the fault current can be reliably cut off when an asymmetric short circuit occurs in the power system. First, when the high-voltage SF6 circuit breaker receives the timing control signal from the relay protection device, its inherent opening and arcing time ensures that the first attempt to break is made at the first zero crossing point of the current. The design of this step utilizes the high insulation strength and stable breaking capacity of the high-voltage SF6 circuit breaker, and strives to successfully cut off the short-circuit current in the first time, thereby quickly isolating the fault and reducing the impact on the system. At the same time, the phase-controlled device of the phase-controlled vacuum circuit breaker of the present invention will use its high-precision prediction algorithm to determine the second zero crossing point. If the second zero crossing point is consistent with the first zero crossing point, both will perform breaking, share the transient recovery voltage, and be more conducive to successful breaking; however, if the high-voltage SF6 circuit breaker fails to successfully break at the first zero crossing point due to some unforeseen factors, the phase-controlled vacuum circuit breaker of the present invention performs a breaking action at the second zero crossing point. This design not only provides redundant protection, ensuring that the short-circuit current can be effectively cut off even in the event of an initial breaking failure, but also further reduces the arc duration and potential damage to the power grid caused by the fault current through the rapid response of the phase-controlled vacuum circuit breaker. In general, this dual protection mechanism significantly improves the reliability and safety of the power system in the face of asymmetric short circuits, while also optimizing the operating efficiency of the circuit breaker and the recovery speed of the system.

[0015] As a preferred embodiment of the first aspect, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point, comprising:

[0016] If the second zero-crossing point is equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point;

[0017] If the second zero-crossing point is not equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker does not break the short-circuit circuit or breaks the short-circuit current at the second zero-crossing point.

[0018] The phase-controlled vacuum circuit breaker does not interrupt the short-circuit circuit or interrupts the short-circuit current at the second zero-crossing point, specifically:

[0019] After the preset time, if the phase-controlled vacuum circuit breaker does not receive the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker does not interrupt the short-circuit current;

[0020] If the phase-controlled vacuum circuit breaker receives the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point; wherein the moment when the short-circuit current is successfully interrupted is the first zero-crossing point.

[0021] In this preferred embodiment, the present application provides an intelligent fault handling mechanism to ensure the safety and reliability of the power system when facing asymmetric short-circuit currents. First, the phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current through an intelligent algorithm to achieve accurate disconnection timing. If the prediction fails or the predicted second zero-crossing point is later than the ideal first zero-crossing point, the system will automatically switch to the backup plan: the high-voltage SF6 circuit breaker uses its inherent opening and arcing time to independently disconnect the short-circuit current at the first zero-crossing point. This step is crucial because it ensures that even if the phase-controlled vacuum circuit breaker fails to make a successful prediction, the fault current can be cut off in time to prevent the fault from expanding.

[0022] After the high-voltage SF6 circuit breaker is successfully disconnected, it will send an action response signal to the phase-controlled device of the phase-controlled vacuum circuit breaker. The purpose of this signal is to inform the phase-controlled device of the current operating status and trigger subsequent logical judgment. If the phase-controlled device has not sent an action response signal to the phase-controlled vacuum circuit breaker within the preset time, the system will decide not to perform the disconnection action, thereby avoiding unnecessary operations and possible equipment damage. On the contrary, if the phase-controlled device has issued an action signal, the phase-controlled vacuum circuit breaker will perform disconnection at the predicted second zero crossing point, even if the short-circuit current has been successfully cut off by the high-voltage SF6 circuit breaker at the first zero crossing point. This design not only improves the fault tolerance of the system, but also optimizes the fault handling process through intelligent control logic, reducing the risks caused by prediction failure or delay. In the end, in either case, the safety and stability of the system are guaranteed, ensuring the continuity and reliability of power supply.

[0023] As a preferred embodiment of the first aspect, after the control relay protection device sends the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively, it also includes:

[0024] The phase-controlled vacuum circuit breaker first bears the transient recovery voltage. When the dielectric recovery strength of the high-voltage SF6 circuit breaker recovers to the preset threshold, the high-voltage SF6 circuit breaker bears the transient recovery voltage.

[0025] In this preferred embodiment, after receiving the timing control signal and successfully breaking the short-circuit current, the phase-controlled vacuum circuit breaker of the present application will first withstand the transient recovery voltage generated by the sudden cut-off of the short-circuit current. Since the vacuum circuit breaker has a faster dielectric recovery speed, it can effectively cope with the high voltage shock in this initial stage, thereby protecting the system from the influence of the voltage peak. Subsequently, when the dielectric recovery strength of the high-voltage SF6 circuit breaker reaches the preset threshold, the high-voltage SF6 circuit breaker takes over the task of bearing the transient recovery voltage. Due to its high insulation strength, the SF6 circuit breaker can safely withstand the remaining transient recovery voltage after the dielectric recovers to a sufficient level, thereby further ensuring the stability of the system and the safety of the equipment. This strategy of bearing the transient recovery voltage in stages not only optimizes the workload of the two circuit breakers, but also makes full use of their respective advantages: the fast response of the phase-controlled vacuum circuit breaker and the high insulation strength of the high-voltage SF6 circuit breaker. Through this intelligent control process, the present invention not only improves the ability of the power system to handle asymmetric short-circuit faults, but also significantly improves the reliability and safety of the system, while also extending the service life of the circuit breaker and reducing maintenance costs.

[0026] In a second aspect, the present application provides a device for suppressing asymmetric short-circuit current. The device for suppressing asymmetric short-circuit current includes a sending module and a breaking module;

[0027] The sending module is used to control the relay protection device to send the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively; wherein the timing control signal is generated by the relay protection device of the power system when a short circuit fault is detected;

[0028] The high-voltage SF6 circuit breaker in the breaking module breaks the short-circuit current at the first zero-crossing point after the opening time and the arcing time according to the timing control signal;

[0029] The phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current according to the timing control signal to obtain a second zero-crossing point; the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0030] The device uses two modules to divide the work and coordinate work to better achieve efficient suppression of asymmetric short-circuit current. The application quickly detects and sends out timing control signals through the relay protection device, ensuring a rapid response to short-circuit faults; the phase-controlled device of the phase-controlled vacuum circuit breaker determines the optimal zero-crossing breaking moment through an intelligent prediction algorithm, which can improve the accuracy and synchronization of breaking, and cooperates with the high-voltage SF6 circuit breaker. The two circuit breakers cooperate to break at the same zero-crossing point, achieving efficient suppression of short-circuit current, so as to solve the problem that the prior art cannot achieve efficient suppression of asymmetric short-circuit current.

[0031] As a preferred embodiment of the second aspect, the high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal, and further includes:

[0032] If the high-voltage SF6 circuit breaker fails to interrupt the short-circuit current at the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0033] In this preferred embodiment, the present application provides a double insurance mechanism to ensure that the fault current can be reliably cut off when an asymmetric short circuit occurs in the power system. First, when the high-voltage SF6 circuit breaker receives the timing control signal from the relay protection device, its inherent opening and arcing time ensures that the first attempt to break is made at the first zero crossing point of the current. The design of this step utilizes the high insulation strength and stable breaking capacity of the high-voltage SF6 circuit breaker, and strives to successfully cut off the short-circuit current in the first time, thereby quickly isolating the fault and reducing the impact on the system. At the same time, the phase-controlled device of the phase-controlled vacuum circuit breaker of the present invention will use its high-precision prediction algorithm to determine the second zero crossing point. If the second zero crossing point is consistent with the first zero crossing point, both will perform breaking, share the transient recovery voltage, and be more conducive to successful breaking; however, if the high-voltage SF6 circuit breaker fails to successfully break at the first zero crossing point due to some unforeseen factors, the phase-controlled vacuum circuit breaker of the present invention performs a breaking action at the second zero crossing point. This design not only provides redundant protection, ensuring that the short-circuit current can be effectively cut off even in the event of an initial breaking failure, but also further reduces the arc duration and potential damage to the power grid caused by the fault current through the rapid response of the phase-controlled vacuum circuit breaker. In general, this dual protection mechanism significantly improves the reliability and safety of the power system in the face of asymmetric short circuits, while also optimizing the operating efficiency of the circuit breaker and the recovery speed of the system.

[0034] As a preferred embodiment of the second aspect, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point, comprising:

[0035] If the second zero-crossing point is equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point;

[0036] If the second zero-crossing point is not equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker does not break the short-circuit circuit or breaks the short-circuit current at the second zero-crossing point.

[0037] The phase-controlled vacuum circuit breaker does not interrupt the short-circuit circuit or interrupts the short-circuit current at the second zero-crossing point, specifically:

[0038] After the preset time, if the phase-controlled vacuum circuit breaker does not receive the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker does not interrupt the short-circuit current;

[0039] If the phase-controlled vacuum circuit breaker receives the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point; wherein the moment when the short-circuit current is successfully interrupted is the first zero-crossing point.

[0040] In this preferred embodiment, the present application provides an intelligent fault handling mechanism to ensure the safety and reliability of the power system when facing asymmetric short-circuit currents. First, the phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current through an intelligent algorithm to achieve accurate disconnection timing. If the prediction fails or the predicted second zero-crossing point is later than the ideal first zero-crossing point, the system will automatically switch to the backup plan: the high-voltage SF6 circuit breaker uses its inherent opening and arcing time to independently disconnect the short-circuit current at the first zero-crossing point. This step is crucial because it ensures that even if the phase-controlled vacuum circuit breaker fails to make a successful prediction, the fault current can be cut off in time to prevent the fault from expanding.

[0041] After the high-voltage SF6 circuit breaker is successfully disconnected, it will send an action response signal to the phase-controlled device of the phase-controlled vacuum circuit breaker. The purpose of this signal is to inform the phase-controlled device of the current operating status and trigger subsequent logical judgment. If the phase-controlled device has not sent an action response signal to the phase-controlled vacuum circuit breaker within the preset time, the system will decide not to perform the disconnection action, thereby avoiding unnecessary operations and possible equipment damage. On the contrary, if the phase-controlled device has issued an action signal, the phase-controlled vacuum circuit breaker will perform disconnection at the predicted second zero crossing point, even if the short-circuit current has been successfully cut off by the high-voltage SF6 circuit breaker at the first zero crossing point. This design not only improves the fault tolerance of the system, but also optimizes the fault handling process through intelligent control logic, reducing the risks caused by prediction failure or delay. In the end, in either case, the safety and stability of the system are guaranteed, ensuring the continuity and reliability of power supply.

[0042] As a preferred embodiment of the second aspect, after the control relay protection device sends the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively, it also includes:

[0043] The phase-controlled vacuum circuit breaker first bears the transient recovery voltage. When the dielectric recovery strength of the high-voltage SF6 circuit breaker recovers to the preset threshold, the high-voltage SF6 circuit breaker bears the transient recovery voltage.

[0044] In this preferred embodiment, after receiving the timing control signal and successfully breaking the short-circuit current, the phase-controlled vacuum circuit breaker of the present application will first withstand the transient recovery voltage generated by the sudden cut-off of the short-circuit current. Since the vacuum circuit breaker has a faster dielectric recovery speed, it can effectively cope with the high voltage shock in this initial stage, thereby protecting the system from the influence of the voltage peak. Subsequently, when the dielectric recovery strength of the high-voltage SF6 circuit breaker reaches the preset threshold, the high-voltage SF6 circuit breaker takes over the task of bearing the transient recovery voltage. Due to its high insulation strength, the SF6 circuit breaker can safely withstand the remaining transient recovery voltage after the dielectric recovers to a sufficient level, thereby further ensuring the stability of the system and the safety of the equipment. This strategy of bearing the transient recovery voltage in stages not only optimizes the workload of the two circuit breakers, but also makes full use of their respective advantages: the fast response of the phase-controlled vacuum circuit breaker and the high insulation strength of the high-voltage SF6 circuit breaker. Through this intelligent control process, the present invention not only improves the ability of the power system to handle asymmetric short-circuit faults, but also significantly improves the reliability and safety of the system, while also extending the service life of the circuit breaker and reducing maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 : A flow chart of an embodiment of a method for suppressing asymmetric short-circuit current provided by the present application;

[0046] Figure 2 : A schematic diagram of the connection between the circuit breaker, phase control device, and relay protection device provided in this application;

[0047] Figure 3 : A schematic diagram of the timing control structure of the circuit breaker disconnection coordination provided in this application;

[0048] Figure 4 : A schematic diagram of the disconnection coordination timing control structure of the circuit breaker provided in the present application when the zero-crossing point predicted by the phase control device is late;

[0049] Figure 5 : A schematic structural diagram of an embodiment of a device for suppressing asymmetric short-circuit current provided in the present application. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] Embodiment 1

[0052] Please refer to Figure 1 , which is a method for suppressing asymmetric short-circuit current provided by an embodiment of the present invention.

[0053] In this embodiment, the process of the method for suppressing asymmetric short-circuit current in the present application is described in detail through steps S01-S02.

[0054] S01: Control the relay protection device to send a timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively; wherein the timing control signal is generated by the relay protection device of the power system when a short circuit fault is detected;

[0055] More specifically, a phase-controlled vacuum circuit breaker and a high-voltage SF6 circuit breaker are configured in series at a key node of the system or in a high-reliability protection situation. When a short-circuit fault occurs, the relay protection device will react quickly, triggering a hierarchical disconnection protection mechanism, and sending an action sequence control signal to the high-voltage SF6 circuit breaker and the fast phase-controlled vacuum circuit breaker. The connection diagram between the circuit breaker, the phase-controlled device, and the relay protection device is as shown in FIG. Figure 2 shown.

[0056] S02: so that the high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal;

[0057] The phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current according to the timing control signal to obtain a second zero-crossing point; the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0058] More specifically, the phase-controlled device of the fast phase-controlled vacuum circuit breaker includes: a current detection unit, a signal processing unit, and an intelligent control unit, etc., which can be combined with an algorithm program to determine the time when a fault occurs, quickly predict the current zero crossing point, and control the fast phase-controlled vacuum circuit breaker to open at a specific time.

[0059] The second zero-crossing point includes: the phase-control device of the fast phase-controlled vacuum circuit breaker predicts the zero-crossing point that can break the short-circuit current at the optimal arcing time through an intelligent algorithm;

[0060] The current detection unit is used to monitor the current waveform and phase shift in real time;

[0061] The signal processing unit is capable of distinguishing short-circuit current from other non-fault types of current fluctuations, thereby reducing false operations.

[0062] The signal processing unit is used to distinguish short-circuit current from other non-fault types of current fluctuations;

[0063] The intelligent control unit is used to quickly predict the current zero-crossing point in combination with an algorithm program.

[0064] More specifically, Figure 3 As shown, when a short circuit fault occurs at time t0, the relay protection system sends an action timing control signal at time t1, and both the fast phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker receive the action timing control signal, but their action times are different.

[0065] The high-voltage SF6 circuit breaker immediately acts after receiving the control signal, and the contacts separate at t3 after the inherent opening time to1, and the arc extinguishes at the current zero crossing point t5 after the arc burning time ta1, completing the disconnection. After receiving the control signal, the fast phase-controlled vacuum circuit breaker predicts the zero crossing point, performs the action at t2 after the delay time td, and separates the contacts at t4 after the inherent opening time to2, and the arc extinguishes at the current zero crossing point t5 after the arc burning time ta2. The two circuit breakers disconnect the short-circuit current at the same zero crossing point t5. The fast phase-controlled vacuum circuit breaker first bears the transient recovery voltage (TRV) in the initial stage. After the SF6 medium recovery strength recovers to a certain extent in the later stage, the SF6 circuit breaker mainly bears the TRV, ensuring the successful disconnection of the short-circuit current and completely isolating the fault point. Among them, the fast phase-controlled vacuum circuit breaker has a zero crossing prediction function, which can disconnect the short-circuit current at the predicted target zero crossing point after the inherent opening time and the optimal arc burning time. Among them, the delay time td is not a fixed value. The calculation method of the delay time is to subtract the inherent opening time of the circuit breaker, the optimal arcing time and a margin, and the action time of the relay protection from the zero point. Among them, the transient recovery voltage (TRV) is the transient recovery voltage generated on the contacts when the arc is generated between the contacts after the circuit breaker contacts are separated and the arc current passes through zero. The arc is extinguished at the moment when the arc current passes through zero. The first voltage that appears between the arc gaps during the voltage recovery process is a voltage with transient characteristics; if the circuit breaker cannot withstand this voltage, there will be a risk of contact breakdown, breaking failure, and equipment damage.

[0066] After receiving the timing control signal and successfully breaking the short-circuit current, the phase-controlled vacuum circuit breaker of the present application will first bear the transient recovery voltage generated by the sudden cutting off of the short-circuit current. Since the vacuum circuit breaker has a faster dielectric recovery speed, it can effectively cope with the high voltage shock in this initial stage, thereby protecting the system from the influence of the voltage peak. Subsequently, when the dielectric recovery strength of the high-voltage SF6 circuit breaker reaches the preset threshold, the high-voltage SF6 circuit breaker takes over the task of bearing the transient recovery voltage. Due to its high insulation strength, the SF6 circuit breaker can safely withstand the remaining transient recovery voltage after the dielectric recovers to a sufficient level, thereby further ensuring the stability of the system and the safety of the equipment. This strategy of bearing the transient recovery voltage in stages not only optimizes the workload of the two circuit breakers, but also makes full use of their respective advantages: the fast response of the phase-controlled vacuum circuit breaker and the high insulation strength of the high-voltage SF6 circuit breaker. Through this intelligent control process, the present invention not only improves the ability of the power system to handle asymmetric short-circuit faults, but also significantly improves the reliability and safety of the system, while also extending the service life of the circuit breaker and reducing maintenance costs.

[0067] As a preferred embodiment of the first embodiment, the high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal, and further includes:

[0068] If the high-voltage SF6 circuit breaker fails to interrupt the short-circuit current at the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0069] In this preferred embodiment, the present application provides a double insurance mechanism to ensure that the fault current can be reliably cut off when an asymmetric short circuit occurs in the power system. First, when the high-voltage SF6 circuit breaker receives the timing control signal from the relay protection device, its inherent opening and arcing time ensures that the first attempt to break is made at the first zero crossing point of the current. The design of this step utilizes the high insulation strength and stable breaking capacity of the high-voltage SF6 circuit breaker, and strives to successfully cut off the short-circuit current in the first time, thereby quickly isolating the fault and reducing the impact on the system. At the same time, the phase-controlled device of the phase-controlled vacuum circuit breaker of the present invention will use its high-precision prediction algorithm to determine the second zero crossing point. If the second zero crossing point is consistent with the first zero crossing point, both will perform breaking, share the transient recovery voltage, and be more conducive to successful breaking; however, if the high-voltage SF6 circuit breaker fails to successfully break at the first zero crossing point due to some unforeseen factors, the phase-controlled vacuum circuit breaker of the present invention performs a breaking action at the second zero crossing point. This design not only provides redundant protection, ensuring that the short-circuit current can be effectively cut off even in the event of an initial breaking failure, but also further reduces the arc duration and potential damage to the power grid caused by the fault current through the rapid response of the phase-controlled vacuum circuit breaker. In general, this dual protection mechanism significantly improves the reliability and safety of the power system in the face of asymmetric short circuits, while also optimizing the operating efficiency of the circuit breaker and the recovery speed of the system.

[0070] As a preferred embodiment of the first embodiment, if the zero-crossing point prediction of the fast phase-controlled vacuum circuit breaker fails after receiving the control signal, or the zero-crossing point predicted by the phase-controlled device is later than the zero-crossing point of the high-voltage SF6 circuit breaker, such as Figure 4 As shown in the figure, the zero-crossing point predicted by the phase-controlled device is at time t6, so the high-voltage SF6 circuit breaker immediately operates after receiving the control signal, and the contacts are separated at time t3 after the inherent opening time to1, and the arc is extinguished at the current zero-crossing point t5 after the arcing time ta1, and the fault is removed. Then, an action response signal is sent to the phase-controlled device of the fast phase-controlled vacuum circuit breaker. If the phase-controlled device has not yet sent an action signal to the fast phase-controlled vacuum circuit breaker at this moment, the phase-controlled device will no longer send an action signal, that is, the fast phase-controlled vacuum circuit breaker will no longer perform the breaking action, as shown in the figure. Figure 4 The middle contact state is shown as 1; if the phase control device has sent an action signal to the fast phase-controlled vacuum circuit breaker at this moment, then Figure 4 As shown in the middle contact state 2, the fast phase-controlled vacuum circuit breaker performs the breaking action normally, and the moment when the fault current is successfully broken is still the zero-crossing point t5 when the high-voltage SF6 circuit breaker breaks the fault current.

[0071] In this preferred embodiment, the present application provides an intelligent fault handling mechanism to ensure the safety and reliability of the power system when facing asymmetric short-circuit currents. First, the phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current through an intelligent algorithm to achieve accurate disconnection timing. If the prediction fails or the predicted second zero-crossing point is later than the ideal first zero-crossing point, the system will automatically switch to the backup plan: the high-voltage SF6 circuit breaker uses its inherent opening and arcing time to independently disconnect the short-circuit current at the first zero-crossing point. This step is crucial because it ensures that even if the phase-controlled vacuum circuit breaker fails to make a successful prediction, the fault current can be cut off in time to prevent the fault from expanding.

[0072] After the high-voltage SF6 circuit breaker is successfully disconnected, it will send an action response signal to the phase-controlled device of the phase-controlled vacuum circuit breaker. The purpose of this signal is to inform the phase-controlled device of the current operating status and trigger subsequent logical judgment. If the phase-controlled device has not sent an action response signal to the phase-controlled vacuum circuit breaker within the preset time, the system will decide not to perform the disconnection action, thereby avoiding unnecessary operations and possible equipment damage. On the contrary, if the phase-controlled device has issued an action signal, the phase-controlled vacuum circuit breaker will perform disconnection at the predicted second zero crossing point, even if the short-circuit current has been successfully cut off by the high-voltage SF6 circuit breaker at the first zero crossing point. This design not only improves the fault tolerance of the system, but also optimizes the fault handling process through intelligent control logic, reducing the risks caused by prediction failure or delay. In the end, in either case, the safety and stability of the system are guaranteed, ensuring the continuity and reliability of power supply.

[0073] The present application ensures a rapid response to a short-circuit fault by quickly detecting and issuing a timing control signal through a relay protection device; the phase-controlled device of the phase-controlled vacuum circuit breaker determines the optimal zero-crossing breaking moment through an intelligent prediction algorithm, which can improve the accuracy and synchronization of the breaking, and cooperates with the high-voltage SF6 circuit breaker. The two circuit breakers cooperate to break at the same zero-crossing point, thereby achieving efficient suppression of the short-circuit current, so as to solve the problem that the prior art cannot achieve efficient suppression of asymmetric short-circuit current.

[0074] Embodiment 2

[0075] Please refer to Figure 5 , which is a device for suppressing asymmetric short-circuit current provided in an embodiment of the present application.

[0076] In this embodiment, the device for suppressing asymmetrical short-circuit current includes a sending module 10 and a breaking module 20 .

[0077] The sending module 10 is used to control the relay protection device to send the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively; wherein the timing control signal is generated by the relay protection device of the power system when a short circuit fault is detected;

[0078] More specifically, a phase-controlled vacuum circuit breaker and a high-voltage SF6 circuit breaker are configured in series at a key node of the system or in a high-reliability protection situation. When a short-circuit fault occurs, the relay protection device will react quickly, triggering a hierarchical disconnection protection mechanism, and sending an action sequence control signal to the high-voltage SF6 circuit breaker and the fast phase-controlled vacuum circuit breaker. The connection diagram between the circuit breaker, the phase-controlled device, and the relay protection device is as shown in FIG. Figure 2 shown.

[0079] The high-voltage SF6 circuit breaker in the breaking module 20 breaks the short-circuit current at the first zero-crossing point after the opening time and the arcing time according to the timing control signal;

[0080] The phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current according to the timing control signal to obtain a second zero-crossing point; the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0081] More specifically, the phase-control device of the fast phase-controlled vacuum circuit breaker includes: a current detection unit, a signal processing unit, and an intelligent control unit, etc., which can be combined with an algorithm program to determine the time when a fault occurs, quickly predict the current zero crossing point, and control the fast phase-controlled vacuum circuit breaker to open at a specific time.

[0082] The second zero-crossing point includes: the phase-control device of the fast phase-controlled vacuum circuit breaker predicts the zero-crossing point that can break the short-circuit current at the optimal arcing time through an intelligent algorithm;

[0083] The current detection unit is used to monitor the current waveform and phase shift in real time;

[0084] The signal processing unit is capable of distinguishing short-circuit current from other non-fault types of current fluctuations, thereby reducing false operations.

[0085] The signal processing unit is used to distinguish short-circuit current from other non-fault types of current fluctuations;

[0086] The intelligent control unit is used to quickly predict the current zero-crossing point in combination with an algorithm program.

[0087] More specifically, Figure 3 As shown, when a short circuit fault occurs at time t0, the relay protection system sends an action timing control signal at time t1, and both the fast phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker receive the action timing control signal, but their action times are different.

[0088] The high-voltage SF6 circuit breaker immediately acts after receiving the control signal, and the contacts separate at t3 after the inherent opening time to1, and the arc extinguishes at the current zero crossing point t5 after the arc burning time ta1, completing the disconnection. After receiving the control signal, the fast phase-controlled vacuum circuit breaker predicts the zero crossing point, performs the action at t2 after the delay time td, and separates the contacts at t4 after the inherent opening time to2, and the arc extinguishes at the current zero crossing point t5 after the arc burning time ta2. The two circuit breakers disconnect the short-circuit current at the same zero crossing point t5. The fast phase-controlled vacuum circuit breaker first bears the transient recovery voltage (TRV) in the initial stage. After the SF6 medium recovery strength recovers to a certain extent in the later stage, the SF6 circuit breaker mainly bears the TRV, ensuring the successful disconnection of the short-circuit current and completely isolating the fault point. Among them, the fast phase-controlled vacuum circuit breaker has a zero crossing prediction function, which can disconnect the short-circuit current at the predicted target zero crossing point after the inherent opening time and the optimal arc burning time. Among them, the delay time td is not a fixed value. The calculation method of the delay time is to subtract the inherent opening time of the circuit breaker, the optimal arcing time and a margin, and the action time of the relay protection from the zero point. Among them, the transient recovery voltage (TRV) is the transient recovery voltage generated on the contacts when the arc is generated between the contacts after the circuit breaker contacts are separated and the arc current passes through zero. The arc is extinguished at the moment when the arc current passes through zero. The first voltage that appears between the arc gaps during the voltage recovery process is a voltage with transient characteristics; if the circuit breaker cannot withstand this voltage, there will be a risk of contact breakdown, breaking failure, and equipment damage.

[0089] After receiving the timing control signal and successfully breaking the short-circuit current, the phase-controlled vacuum circuit breaker of the present application will first bear the transient recovery voltage generated by the sudden cutting off of the short-circuit current. Since the vacuum circuit breaker has a faster dielectric recovery speed, it can effectively cope with the high voltage shock in this initial stage, thereby protecting the system from the influence of the voltage peak. Subsequently, when the dielectric recovery strength of the high-voltage SF6 circuit breaker reaches the preset threshold, the high-voltage SF6 circuit breaker takes over the task of bearing the transient recovery voltage. Due to its high insulation strength, the SF6 circuit breaker can safely withstand the remaining transient recovery voltage after the dielectric recovers to a sufficient level, thereby further ensuring the stability of the system and the safety of the equipment. This strategy of bearing the transient recovery voltage in stages not only optimizes the workload of the two circuit breakers, but also makes full use of their respective advantages: the fast response of the phase-controlled vacuum circuit breaker and the high insulation strength of the high-voltage SF6 circuit breaker. Through this intelligent control process, the present invention not only improves the ability of the power system to handle asymmetric short-circuit faults, but also significantly improves the reliability and safety of the system, while also extending the service life of the circuit breaker and reducing maintenance costs.

[0090] As a preferred embodiment of the second embodiment, the high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal, and further includes:

[0091] If the high-voltage SF6 circuit breaker fails to interrupt the short-circuit current at the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

[0092] In this preferred embodiment, the present application provides a double insurance mechanism to ensure that the fault current can be reliably cut off when an asymmetric short circuit occurs in the power system. First, when the high-voltage SF6 circuit breaker receives the timing control signal from the relay protection device, its inherent opening and arcing time ensures that the first attempt to break is made at the first zero crossing point of the current. The design of this step utilizes the high insulation strength and stable breaking capacity of the high-voltage SF6 circuit breaker, and strives to successfully cut off the short-circuit current in the first time, thereby quickly isolating the fault and reducing the impact on the system. At the same time, the phase-controlled device of the phase-controlled vacuum circuit breaker of the present invention will use its high-precision prediction algorithm to determine the second zero crossing point. If the second zero crossing point is consistent with the first zero crossing point, both will perform breaking, share the transient recovery voltage, and be more conducive to successful breaking; however, if the high-voltage SF6 circuit breaker fails to successfully break at the first zero crossing point due to some unforeseen factors, the phase-controlled vacuum circuit breaker of the present invention performs a breaking action at the second zero crossing point. This design not only provides redundant protection, ensuring that the short-circuit current can be effectively cut off even in the event of an initial breaking failure, but also further reduces the arc duration and potential damage to the power grid caused by the fault current through the rapid response of the phase-controlled vacuum circuit breaker. In general, this dual protection mechanism significantly improves the reliability and safety of the power system in the face of asymmetric short circuits, while also optimizing the operating efficiency of the circuit breaker and the recovery speed of the system.

[0093] As a preferred embodiment of the second embodiment, if the zero-crossing point prediction of the fast phase-controlled vacuum circuit breaker fails after receiving the control signal, or the zero-crossing point predicted by the phase-controlled device is later than the zero-crossing point of the high-voltage SF6 circuit breaker, such as Figure 4 As shown in the figure, the zero-crossing point predicted by the phase-controlled device is at time t6, so the high-voltage SF6 circuit breaker immediately operates after receiving the control signal, and the contacts are separated at time t3 after the inherent opening time to1, and the arc is extinguished at the current zero-crossing point t5 after the arcing time ta1, and the fault is removed. Then, an action response signal is sent to the phase-controlled device of the fast phase-controlled vacuum circuit breaker. If the phase-controlled device has not yet sent an action signal to the fast phase-controlled vacuum circuit breaker at this moment, the phase-controlled device will no longer send an action signal, that is, the fast phase-controlled vacuum circuit breaker will no longer perform the breaking action, as shown in the figure. Figure 4 The middle contact state is shown as 1; if the phase control device has sent an action signal to the fast phase-controlled vacuum circuit breaker at this moment, then Figure 4As shown in the middle contact state 2, the fast phase-controlled vacuum circuit breaker performs the breaking action normally, and the moment when the fault current is successfully broken is still the zero-crossing point t5 when the high-voltage SF6 circuit breaker breaks the fault current.

[0094] In this preferred embodiment, the present application provides an intelligent fault handling mechanism to ensure the safety and reliability of the power system when facing asymmetric short-circuit currents. First, the phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current through an intelligent algorithm to achieve accurate disconnection timing. If the prediction fails or the predicted second zero-crossing point is later than the ideal first zero-crossing point, the system will automatically switch to the backup plan: the high-voltage SF6 circuit breaker uses its inherent opening and arcing time to independently disconnect the short-circuit current at the first zero-crossing point. This step is crucial because it ensures that even if the phase-controlled vacuum circuit breaker fails to make a successful prediction, the fault current can be cut off in time to prevent the fault from expanding.

[0095] After the high-voltage SF6 circuit breaker is successfully disconnected, it will send an action response signal to the phase-controlled device of the phase-controlled vacuum circuit breaker. The purpose of this signal is to inform the phase-controlled device of the current operating status and trigger subsequent logical judgment. If the phase-controlled device has not sent an action response signal to the phase-controlled vacuum circuit breaker within the preset time, the system will decide not to perform the disconnection action, thereby avoiding unnecessary operations and possible equipment damage. On the contrary, if the phase-controlled device has issued an action signal, the phase-controlled vacuum circuit breaker will perform disconnection at the predicted second zero crossing point, even if the short-circuit current has been successfully cut off by the high-voltage SF6 circuit breaker at the first zero crossing point. This design not only improves the fault tolerance of the system, but also optimizes the fault handling process through intelligent control logic, reducing the risks caused by prediction failure or delay. In the end, in either case, the safety and stability of the system are guaranteed, ensuring the continuity and reliability of power supply.

[0096] The device uses two modules to divide the work and coordinate work to better achieve efficient suppression of asymmetric short-circuit current. The application quickly detects and sends out timing control signals through the relay protection device, ensuring a rapid response to short-circuit faults; the phase-controlled device of the phase-controlled vacuum circuit breaker determines the optimal zero-crossing breaking moment through an intelligent prediction algorithm, which can improve the accuracy and synchronization of breaking, and cooperates with the high-voltage SF6 circuit breaker. The two circuit breakers cooperate to break at the same zero-crossing point, achieving efficient suppression of short-circuit current, so as to solve the problem that the prior art cannot achieve efficient suppression of asymmetric short-circuit current.

[0097] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for suppressing asymmetric short-circuit current, characterized in that: include: Controlling the relay protection device to send a timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively; wherein the timing control signal is generated by the relay protection device of the power system when a short circuit fault is detected; So that the high-voltage SF6 circuit breaker breaks the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal; The phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current according to the timing control signal to obtain a second zero-crossing point; the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

2. The method for suppressing asymmetric short-circuit current according to claim 1, characterized in that: The high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal, and further includes: If the high-voltage SF6 circuit breaker fails to interrupt the short-circuit current at the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

3. The method for suppressing asymmetric short-circuit current according to claim 1, characterized in that: The phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point, comprising: If the second zero-crossing point is equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point; If the second zero-crossing point is not equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker does not interrupt the short-circuit current or interrupts the short-circuit current at the second zero-crossing point.

4. The method for suppressing asymmetric short-circuit current according to claim 3, characterized in that: The phase-controlled vacuum circuit breaker does not interrupt the short-circuit circuit or interrupts the short-circuit current at the second zero-crossing point, specifically: After the preset time, if the phase-controlled vacuum circuit breaker does not receive the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker does not interrupt the short-circuit current; If the phase-controlled vacuum circuit breaker receives the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point; wherein the moment when the short-circuit current is successfully interrupted is the first zero-crossing point.

5. The method for suppressing asymmetric short-circuit current according to claim 1, characterized in that: After the control relay protection device sends the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively, it also includes: The phase-controlled vacuum circuit breaker first bears the transient recovery voltage. When the dielectric recovery strength of the high-voltage SF6 circuit breaker recovers to the preset threshold, the high-voltage SF6 circuit breaker bears the transient recovery voltage.

6. A device for suppressing asymmetric short-circuit current, characterized in that: Including sending module and breaking module; The sending module is used to control the relay protection device to send the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively; wherein the timing control signal is generated by the relay protection device of the power system when a short circuit fault is detected; The high-voltage SF6 circuit breaker in the breaking module breaks the short-circuit current at the first zero-crossing point after the opening time and the arcing time according to the timing control signal; The phase-controlled device of the phase-controlled vacuum circuit breaker predicts the zero-crossing point of the short-circuit current according to the timing control signal to obtain a second zero-crossing point; the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

7. The device for suppressing asymmetrical short-circuit current according to claim 6, characterized in that: The high-voltage SF6 circuit breaker interrupts the short-circuit current at the first zero-crossing point after the opening time and arcing time according to the timing control signal, and further includes: If the high-voltage SF6 circuit breaker fails to interrupt the short-circuit current at the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point.

8. The device for suppressing asymmetrical short-circuit current according to claim 6, characterized in that: The phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point, comprising: If the second zero-crossing point is equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point; If the second zero-crossing point is not equal to the first zero-crossing point, the phase-controlled vacuum circuit breaker does not interrupt the short-circuit current or interrupts the short-circuit current at the second zero-crossing point.

9. The device for suppressing asymmetrical short-circuit current according to claim 8, characterized in that: The phase-controlled vacuum circuit breaker does not interrupt the short-circuit circuit or interrupts the short-circuit current at the second zero-crossing point, specifically: After the preset time, if the phase-controlled vacuum circuit breaker does not receive the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker does not interrupt the short-circuit current; If the phase-controlled vacuum circuit breaker receives the action response signal sent by the phase-controlled device, the phase-controlled vacuum circuit breaker interrupts the short-circuit current at the second zero-crossing point; wherein the moment when the short-circuit current is successfully interrupted is the first zero-crossing point.

10. The device for suppressing asymmetrical short-circuit current according to claim 6, characterized in that: After the control relay protection device sends the timing control signal to the phase-controlled vacuum circuit breaker and the high-voltage SF6 circuit breaker respectively, it also includes: The phase-controlled vacuum circuit breaker first bears the transient recovery voltage. When the dielectric recovery strength of the high-voltage SF6 circuit breaker recovers to the preset threshold, the high-voltage SF6 circuit breaker bears the transient recovery voltage.

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