Current transfer generator circuit breaker

Abstract

Disclosed is a current transfer type generator circuit breaker, which comprises a main current branch, a current limiting transfer branch and a fast switch; the main current branch comprises a high-speed mechanical switch S1, the two ends of the high-speed mechanical switch S1 are directly connected with circuit breaker outgoing terminals A1 and A2, and the current limiting transfer branch is connected in parallel with the two ends of the main current branch, wherein a transfer capacitor C, an inductor L and a vacuum arc-extinguishing chamber VS1 are connected in series, and then the series connection is connected in parallel with a current limiting resistor R; the fast switch S2 is located between the current limiting transfer branch and the main current branch, in the vacuum arc-extinguishing chamber VS1, the moving contact is connected with a pull rod and connected with an external fast operating mechanism, a pair of trigger electrodes are respectively arranged in the middle of the static contact and the middle of the moving contact, the pair of trigger electrodes are respectively connected with wiring terminals B3 and B4 outside the shell, the front end of the trigger electrode is provided with a trigger pin, and a gap is left in the trigger pin as a discharge channel of a trigger pulse.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of circuit breakers, in particular to a current transfer type generator circuit breaker. BACKGROUND

[0002] In large power stations, generator circuit breakers are the core equipment to ensure safe and reliable operation of the system. In the circuit breaker based on capacitor discharge to realize current transfer, the control switch of LC branch generally uses thyristor, vacuum trigger gap or ball gap. When the current level is high, it will face the limitations of insufficient breaking capacity, too large transferred current, insufficient large current life and high cost, which is difficult to meet the fault protection requirements of future million kilowatt and above generator units. In view of the shortcomings of the above breaking scheme, the present application proposes a current transfer type generator circuit breaker using high-voltage triggered fast conduction vacuum interrupter, and proposes to use a vacuum interrupter with high-voltage triggered conduction function to replace the thyristor or vacuum trigger gap in the LC oscillation branch of the circuit breaker, so that the circuit breaker has the advantages of fast breaking speed, strong current suppression capability and large breaking capacity, which can meet the operation requirements of large power systems.

[0003] The above information disclosed in the background section is only used to enhance the understanding of the background of the present application, and therefore can contain information that is not prior art known to those of ordinary skill in the art. SUMMARY

[0004] In view of the shortcomings or defects of the prior art, a current transfer type generator circuit breaker is provided, which uses a high-voltage triggered fast conduction vacuum interrupter in the transferred current branch, uses the mechanical switch to bear the transferred current with longer duration, realizes high current injection and low conduction resistance, and realizes low delay conduction and low closing time dispersion by controlling the action of high-speed mechanical switch, high-voltage triggered fast conduction vacuum interrupter triggering and action, triggering the input of transfer and current limiting branch according to a specific time sequence, realizing current fast transfer and current limiting, and finally completing breaking at the zero crossing point.

[0005] The purpose of the present application is achieved by the following technical solutions.

[0006] A current transfer type generator circuit breaker comprises a main current branch, a current limiting transfer branch and a fast switch.

[0007] The main current branch comprises a high-speed mechanical switch S1, and the two ends of the high-speed mechanical switch S1 are directly connected with the outgoing line end A1 and the outgoing line end A2 of the circuit breaker.

[0008] The current limiting transfer branch is connected in parallel at both ends of the main current branch, wherein the transfer capacitor C, the inductor L and the vacuum interrupter VS1 are connected in series, and then connected in parallel with the current limiting resistor R.

[0009] The fast switch S2 is located between the current-limiting transfer branch and the main current branch.

[0010] The vacuum interrupter VS1 comprises,

[0011] The shell is internally provided with a vacuum cavity of the vacuum interrupter.

[0012] The static contact is fixed at one end in the shell and connected with the terminal B1 outside the shell.

[0013] The dynamic contact is arranged at the other end of the static contact in the shell and connected with the terminal B2 outside the shell, and the dynamic contact is connected with the pull rod and connected with the external fast operating mechanism.

[0014] A pair of trigger electrodes are arranged at the middle of the static contact and the middle of the dynamic contact respectively, and the pair of trigger electrodes are connected with the terminal B3 and the terminal B4 outside the shell respectively, and the front end of the trigger electrode is provided with a trigger pin, and the trigger pin is provided with a gap as a discharge channel of the trigger pulse.

[0015] In the current transfer type generator circuit breaker, under the normal through-flow state of the system, the system current flows through the high-speed mechanical switch S1 of the main current branch; when the forward short-circuit current is turned off, the control system sends an opening action instruction to the high-speed mechanical switch S1, the high-speed mechanical switch S1 is disconnected, the vacuum interrupter VS1 is triggered to conduct, and the current is transferred to the current-limiting transfer branch; after the current of the high-speed mechanical switch S1 is zero, the current enters the current-limiting transfer branch, the fault current is limited, and after the current is limited, the control system sends an opening instruction to the fast switch S2; after the current of the fast switch S2 is zero, the arc is extinguished, and the short-circuit current limiting opening is completed; under the reverse opening condition, the high-voltage trigger vacuum interrupter VS1 is triggered to close, the current-limiting transfer branch is first subjected to current oscillation, the capacitor voltage is reversed, then the control system sends an opening action instruction to the high-speed mechanical switch S1, and then the current of the high-speed mechanical switch S1 is zero and disconnected, the current enters the current-limiting transfer branch, the fault current is limited, the control system sends an opening instruction to the fast switch S2, and after the current of the fast switch S2 is zero, the arc is extinguished, and the short-circuit current limiting opening is completed.

[0016] In the current transfer type generator circuit breaker, the dynamic contact is connected with the terminal B2 through a corrugated pipe or a sliding connection mode.

[0017] In the current transfer type generator circuit breaker, the static contact or the dynamic contact is an arc-leading angle contact, a flat plate contact, or a contact with horizontal or vertical magnetic slots.

[0018] In the current transfer type generator circuit breaker, the contact material of the static contact or the dynamic contact is pure copper, copper-tungsten alloy, or copper-chromium alloy.

[0019] In the current-transfer generator circuit breaker, the trigger electrode is a trigger electrode embedded between the moving and stationary contacts, and its external contact is the source; the vacuum interrupter VS1 uses different trigger electrodes for forward and reverse triggering.

[0020] In the current-transfer type generator circuit breaker, when the vacuum interrupter VS1 closes, it can control the trigger to conduct when the moving contact moves a specific stroke, causing the trigger gap to break down, resulting in current discharge. High-density metal vapor plasma is generated in the trigger gap and is rapidly injected into the high-voltage main gap, so that the moving contact breaks down and conducts before contact.

[0021] In the current-transfer generator circuit breaker, the high-speed mechanical switch S1 is an SF6, air, or liquid switch based on electromagnetic repulsion or high-speed motor drive, and the fast switch S2 is a vacuum fast switch.

[0022] In the current-transfer generator circuit breaker, the main current branch includes multiple high-speed mechanical vacuum switches S1 connected in parallel.

[0023] In the current-transfer type generator circuit breaker, the transfer capacitor C includes any one or a combination of multiple of the following: film capacitor, organic dielectric capacitor, inorganic dielectric capacitor, electrolytic capacitor, electrothermal capacitor, and air dielectric capacitor.

[0024] Beneficial effects

[0025] This invention features fast current transfer speed, strong current injection capability, and strong breaking capacity. To achieve current transfer in the circuit breaker, because the transfer current is very large and the timing of the transfer current injection is extremely precise, the current, after passing through the switch, should form as many high-frequency current oscillations as possible. In other words, the resistance formed by the switch should be as small as possible, and the oscillation should decay very slowly (if the main break does not open during one oscillation, there is a second chance). Therefore, the three key points are large current, accurate timing, and low resistance. While using a trigger gap can achieve microsecond-level timing precision, it struggles to withstand large currents and has a relatively short lifespan. Conversely, using only a fast mechanical switch can withstand large currents, but timing precision cannot be achieved. Furthermore, in existing technologies, after the mechanical switch is triggered and begins to close, the opening gap is still relatively large. At this time, the arc is long, the voltage is high, and the resistance is relatively large, which is not conducive to continuous high-frequency oscillation. The large opening gap also means the mechanism cannot close in time, and the high-frequency current is easily interrupted during oscillation. This invention, based on the circuit breaker waveform, pre-activates the mechanism, quickly achieving high-voltage triggering and conduction just as the mechanism is about to close, thus achieving precise conduction. This is not merely about making the switch conduct faster, but about reducing the conduction dispersion of the fast-acting mechanical switch. By utilizing a vacuum interrupter with high-voltage triggering and rapid conduction function, rapid and accurate conduction is achieved, enabling the pre-charged capacitor to discharge quickly and inject reverse current into the main branch, thereby achieving rapid current-limiting interruption of short-circuit faults at the generator outlet.

[0026] The above description is merely an overview of the technical solution of the present invention. In order to make the technical means of the present invention clearer and more understandable, so that those skilled in the art can implement it according to the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more obvious and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0027] Various other advantages and benefits of the present invention will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0028] In the attached diagram:

[0029] Figure 1 This is a schematic diagram of the structure of a current-transfer generator circuit breaker according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the vacuum interrupter of a current-transfer generator circuit breaker according to an embodiment of the present invention;

[0031] Figures 3(a) to 3(e) A schematic diagram of the operation of a current-transfer generator circuit breaker when interrupting short-circuit current according to an embodiment of the present invention;

[0032] Figure 4 A waveform diagram of a current-transfer generator circuit breaker interrupting short-circuit current according to an embodiment of the present invention.

[0033] Figure 5 A schematic diagram of LC current injection when a current-transfer generator circuit breaker interrupts a reverse short-circuit current according to an embodiment of the present invention.

[0034] The present invention will be further explained below with reference to the accompanying drawings and embodiments. Detailed Implementation

[0035] The following will refer to the appendix. Figures 1 to 5Specific embodiments of the invention will be described in more detail below. While specific embodiments of the invention are shown in the accompanying drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0036] It should be noted that certain terms are used in the specification and claims to refer to specific components. Those skilled in the art will understand that different terms may be used to refer to the same component. This specification and claims do not distinguish components based on differences in terminology, but rather on differences in function. The terms "comprising" or "including" used throughout the specification and claims are open-ended and should be interpreted as "comprising but not limited to." The following descriptions are preferred embodiments for carrying out the invention; however, these descriptions are for the purpose of understanding the general principles of the specification and are not intended to limit the scope of the invention. The scope of protection of this invention is determined by the appended claims.

[0037] To facilitate understanding of the embodiments of the present invention, the following will provide further explanation and description with reference to the accompanying drawings and several specific embodiments, and the accompanying drawings do not constitute a limitation on the embodiments of the present invention.

[0038] like Figures 1 to 5 As shown, a current-transfer type generator circuit breaker includes a main current branch, a current-limiting transfer branch, and a fast switch. The main current branch includes a high-speed mechanical switch S1, with its two ends directly connected to the circuit breaker's output terminals A1 and A2. The current-limiting transfer branch is connected in parallel across the main current branch. A transfer capacitor C, an inductor L, and a vacuum interrupter VS1 are connected in series, and then in parallel with a current-limiting resistor R. The fast switch S2 is located between the current-limiting transfer branch and the main current branch. The vacuum interrupter VS1 includes…

[0039] The outer casing 6 contains a vacuum chamber 4 with a vacuum interrupter inside;

[0040] The stationary contact 1 has one end fixed inside the housing 6 and connected to the wiring terminal B1 outside the housing 6;

[0041] The moving contact 2 is located inside the housing 6 at the other end relative to the stationary contact 1 and is connected to the wiring terminal B2 outside the housing 6. The moving contact 2 is connected to the pull rod and to the external quick-operation mechanism.

[0042] A pair of trigger electrodes 3 are respectively located in the middle of the stationary contact 1 and the middle of the moving contact 2. The pair of trigger electrodes 3 are respectively connected to the wiring terminal B3 and the wiring terminal B4 outside the housing 6. The front end of the trigger electrode 3 is provided with a trigger pin, and the trigger pin has a gap as a discharge channel for the trigger pulse.

[0043] In a preferred embodiment of the current-transfer type generator circuit breaker, under normal system current conditions, the system current flows through the high-speed mechanical switch S1 of the main current branch. When the forward short-circuit current is interrupted, the control system sends a tripping command to the high-speed mechanical switch S1, which disconnects the arc, triggering the vacuum interrupter VS1 to conduct. The current is transferred to the current-limiting transfer branch. When the current in the high-speed mechanical switch S1 crosses zero, the current enters the current-limiting transfer branch, and the fault current is limited. After the current is limited, the control system sends a tripping command to the fast switch S2. The command is given that the arc is extinguished after the current in the fast switch S2 crosses zero, completing the short-circuit current limiting interruption. Under reverse interruption conditions, the high-voltage trigger vacuum interrupter VS1 is triggered to close. The current limiting transfer branch first undergoes a current oscillation, and the capacitor voltage is reversed. Then, the control system sends a tripping command to the high-speed mechanical switch S1. After that, the current in the high-speed mechanical switch S1 is disconnected after crossing zero, and the current enters the current limiting transfer branch. The fault current is limited. The control system sends a tripping command to the fast switch S2. The arc is extinguished after the current in the fast switch S2 crosses zero, completing the short-circuit current limiting interruption.

[0044] In a preferred embodiment of the current-transfer generator circuit breaker, the moving contact 2 is connected to the terminal B2 via a bellows or a sliding connection.

[0045] In a preferred embodiment of the current-transfer type generator circuit breaker, the stationary contact 1 or the moving contact 2 is an arc-inducing angle contact, a flat contact, or a contact with transverse or longitudinal magnetic slots.

[0046] In a preferred embodiment of the current-transfer generator circuit breaker, the contact material of the stationary contact 1 or the moving contact 2 is pure copper, copper-tungsten alloy, or copper-chromium alloy.

[0047] In a preferred embodiment of the current-transfer generator circuit breaker, the trigger electrode 3 is a trigger electrode embedded between the moving and stationary contacts 1, and its external contact is the source; the vacuum interrupter VS1 is triggered by different trigger electrodes 3 in the forward and reverse directions.

[0048] In a preferred embodiment of the current-transfer generator circuit breaker, when the vacuum interrupter VS1 closes, the moving contact 2 can be controlled to trigger conduction during a specific stroke, causing the trigger gap to break down and resulting in current discharge. High-density metal vapor plasma is generated in the trigger gap and rapidly injected into the high-voltage main gap, causing the moving contact 2 to break down and conduct before contact. This achieves pre-conduction of the vacuum circuit breaker, thereby reducing the dispersion of closing time and improving closing performance. After trigger conduction, the break closes rapidly, significantly increasing the current transfer capacity and conduction life of the contacts, and avoiding contact erosion problems caused by large currents.

[0049] In a preferred embodiment of the current-transfer generator circuit breaker, the high-speed mechanical switch S1 is an SF6, air, or liquid switch based on electromagnetic repulsion or driven by a high-speed motor, and the fast switch S2 is a vacuum fast switch.

[0050] In a preferred embodiment of the current-transfer generator circuit breaker, the main current branch includes multiple high-speed mechanical vacuum switches S1 connected in parallel.

[0051] In a preferred embodiment of the current-transfer generator circuit breaker, the transfer capacitor C includes any one or a combination of multiple of the following: film capacitor, organic dielectric capacitor, inorganic dielectric capacitor, electrolytic capacitor, electrothermal capacitor, and air dielectric capacitor.

[0052] In one embodiment, the vacuum chamber 4 is provided with a shield 5.

[0053] In one embodiment, the moving contact 2 is connected to the bellows sealing connection 7.

[0054] In one embodiment, Figures 3(a) to 3(e) The specific process of a circuit breaker interrupting a short-circuit current is given:

[0055] (1) As shown in Figure 3(a), under normal current flow conditions, the system current flows in from the output terminal A1, and flows out from the output terminal A2 after passing through the mechanical switch S1.

[0056] (2) As shown in Figure 3(b), when the detection system detects a short circuit fault in the system, it notifies the control system, and the control system issues a trip command, the high-speed mechanical switch S1 opens, and arcing begins;

[0057] (3) As shown in Figure 3(c), the high voltage triggers the rapid conduction of the vacuum interrupter VS1, and the pre-charge capacitor rapidly discharges to inject reverse current into the main branch, and the current in the main branch is transferred to the current-limiting transfer branch.

[0058] (4) As shown in Figure 3(d), when the high voltage triggers the rapid conduction of the vacuum interrupter, the moving contact 2 starts to operate first. When the distance between the moving and stationary contacts 1 reaches a certain value, the trigger electrode 3 at terminals B3 and B4 inputs a trigger pulse, and the trigger needle discharges and breaks down the vacuum gap. After the vacuum gap breaks down, the interrupter is turned on when the contacts are not in contact. Then the mechanical switch is closed, and the current is conducted by the contacts.

[0059] (5) As shown in Figure 3(e), when the current in S1 crosses zero, the current enters the current limiting branch, the fault current is limited, the system current consumes energy through resistor R, the control system sends a trip command to the fast switch S2, the arc in S2 is extinguished after the current crosses zero, and the short circuit current limiting interruption is completed.

[0060] Figure 4The waveform diagrams of the circuit breaker interrupting the short-circuit current are given. Among them, curve 1 is the total system current, curve 2 is the LC branch current, curve 3 is the main current branch current, and curve 4 is the current limiting branch current.

[0061] Figure 5 A schematic diagram illustrating the LC current injection principle when the circuit breaker of this invention interrupts a reverse short-circuit current is provided. When a reverse fault current is generated, the LC circuit needs to oscillate once before injecting current. During the positive half-cycle, the current and the fault current are superimposed in the same direction. During the negative half-cycle, the capacitor voltage reverses, and the injected current achieves zero crossing of the main branch current near the peak value of the LC oscillation current. The subsequent interruption logic is the same as when interrupting a forward fault current.

[0062] Although embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments and application fields described above. The specific embodiments described above are merely illustrative and instructive, and not restrictive. Those skilled in the art can make many other forms based on the guidance of this specification and without departing from the scope of protection of the claims of the present invention, and all of these are within the scope of protection of the present invention.

Claims

1. A current transfer generator circuit breaker characterized by, It includes: The main current branch, current limiting transfer branch and fast switch; The main current branch includes high-speed mechanical switch S1, and the high-speed mechanical switch S1 is directly connected with the breaker outgoing line end A1 and the outgoing line end A2 at both ends of the break; The current limiting transfer branch is connected in parallel at both ends of the main current branch, wherein the transfer capacitor C, the inductor L and the vacuum interrupter VS1 are connected in series, and then the series connection is connected in parallel with the current limiting resistor R; The fast switch S2 is located between the current limiting transfer branch and the main current branch; The vacuum interrupter VS1 includes, The shell is provided with a vacuum cavity of the vacuum interrupter in the shell; The static contact is fixed at one end in the shell and connected with the wiring end B1 outside the shell; The moving contact is arranged at the other end of the static contact in the shell and connected with the wiring end B2 outside the shell, and the moving contact is connected with the pull rod and connected with the external fast operating mechanism; A pair of trigger electrodes are arranged in the middle of the static contact and the middle of the moving contact, respectively, and the pair of trigger electrodes are connected with the wiring end B3 and the wiring end B4 outside the shell, respectively, and the front end of the trigger electrode is provided with a trigger pin, and the trigger pin has a gap as a discharge channel of the trigger pulse; When the system is in normal current passing state, the system current flows through the high-speed mechanical switch S1 of the main current branch; when the forward short-circuit current is turned off, the control system sends a tripping action instruction to the high-speed mechanical switch S1, the high-speed mechanical switch S1 is disconnected, the vacuum interrupter VS1 is triggered to conduct, and the current is transferred to the current limiting transfer branch; when the current of the high-speed mechanical switch S1 is zero, the current enters the current limiting transfer branch, the fault current is limited, and when the current is limited, the control system sends a tripping instruction to the fast switch S2, the current in the fast switch S2 is zero after arc extinction, and the short-circuit current limiting opening is completed; under the reverse opening condition, the high-voltage trigger vacuum interrupter VS1 is triggered to close, the current limiting transfer branch is first subjected to current oscillation, the capacitor voltage is reversed, then the control system sends a tripping action instruction to the high-speed mechanical switch S1, then the current of the high-speed mechanical switch S1 is zero and is disconnected, the current enters the current limiting transfer branch, the fault current is limited, the control system sends a tripping instruction to the fast switch S2, the current in the fast switch S2 is zero after arc extinction, and the short-circuit current limiting opening is completed; When the vacuum interrupter VS1 is closed, the trigger conduction can be controlled when the moving contact moves a specific stroke, the trigger gap is broken down, the current is discharged, high-density metal vapor plasma is generated in the trigger gap, and is quickly injected into the high-voltage main gap, so that the moving contact is broken down and conducted before contact.

2. The current transfer generator circuit breaker of claim 1, wherein: The moving contact is connected with the wiring end B2 in a sliding connection mode.

3. The current transfer generator circuit breaker of claim 1, wherein: The static contact or the moving contact is a contact with an arc leading angle, or a contact with a flat plate, or a contact with a transverse magnetic slot, or a contact with a longitudinal magnetic slot.

4. The current transfer generator circuit breaker of claim 1, wherein: The contact material of the static contact or the moving contact is pure copper, copper tungsten alloy or copper chromium alloy.

5. The current transfer generator circuit breaker of claim 1, wherein: The trigger electrode is a trigger electrode embedded in the middle of the moving contact and the static contact, and is connected with a trigger source; the vacuum interrupter VS1 uses different trigger electrodes for forward and reverse triggering.

6. The current transfer generator circuit breaker of claim 1, wherein: The high-speed mechanical switch S1 is an SF6 switch driven by electromagnetic repulsive force or an SF6 switch driven by a high-speed motor or an air switch or a liquid switch, and the fast switch S2 is a vacuum fast switch.

7. The current transfer generator circuit breaker of claim 1, wherein: The main current branch comprises a plurality of parallel high-speed mechanical vacuum switches S1.

8. The current transfer generator circuit breaker of claim 1, wherein: The transfer capacitor C comprises a thin-film capacitor.

9. The current transfer generator circuit breaker of claim 1, wherein: The transfer capacitor C comprises an organic dielectric capacitor.

10. The current transfer generator circuit breaker of claim 1, wherein: The transfer capacitor C comprises an inorganic dielectric capacitor.

11. The current transfer generator circuit breaker of claim 1, wherein: The transfer capacitor C comprises an electrolytic capacitor.

12. The current transfer generator circuit breaker of claim 1, wherein: The transfer capacitor C comprises an air dielectric capacitor.

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