High-capacity circuit breaker

Abstract

The invention provides a high-capacity circuit breaker, and belongs to the field of power equipment.The circuit breaker comprises a main branch, a transfer branch and a fuse branch, the main branch comprises a high-speed mechanical switch S, and the transfer branch comprises a transfer capacitor C, a transfer inductor L and a thyristor module; the transfer capacitor C, the transfer inductor L and the thyristor module are connected in series and then connected to the two ends of the high-speed mechanical switch S in parallel, the fuse branch comprises at least one fuse F, and the fuse F is connected to the two ends of the high-speed mechanical switch S in parallel. According to the high-capacity circuit breaker, the transfer branch circuit is connected to the main branch circuit in parallel, reverse current is directly injected into the main branch circuit through the transfer branch circuit, the current amplitude of the main branch circuit can be rapidly reduced, the current of the main branch circuit is forced to rapidly drop and cross zero, manual zero crossing of the main branch circuit can be rapidly and reliably achieved, and finally switching-on and switching-off are completed through the fuse. And the device is suitable for the switching-on and switching-off working condition of the outlet short-circuit current of an ultra-large-capacity generator, and is completely environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of electric power equipment, and in particular to a large-capacity circuit breaker. Background Art

[0002] Million-kilowatt large-scale generator sets have been vigorously promoted and applied because of their significant advantages in economic benefits and power generation efficiency. However, their short-circuit current is very high, usually containing a huge DC component, and is prone to current delay zero crossing, which places high demands on the breaking capacity of the generator circuit breaker. At present, large-capacity generator circuit breakers mostly use the sulfur hexafluoride breaking principle, which generates a high arc voltage during the contact opening process to force the current to cross zero, resulting in a long breaking time and huge arc energy accumulation. At the same time, sulfur hexafluoride is also an environmentally unfriendly gas, which does not meet the development requirements of environmentally friendly power equipment in the future.

[0003] In the prior art, the Chinese invention patent application with publication number CN113555857A, "Quick Fuse Device Based on Arc Voltage Enhanced Transfer", generates a magnetic field through a transverse magnetic current loop, regulates the arc shape, increases its resistance and generates oscillations, and rapidly increases the arc voltage to turn on the fuse. The short-circuit current energy is dissipated during the fusing period, thereby realizing the function of quickly breaking or limiting the short-circuit current under the short-circuit fault condition of the medium-voltage DC system. The fast fuse device increases the arc voltage of the high-speed switch by adding an external transverse magnetic circuit, thereby forcing the current to transfer. The increase in the arc voltage determines the speed of the current transfer. There is still room for optimization in the current transfer speed and zero-crossing reliability of the fast fuse device. In practical applications, the arc voltage cannot be increased too high, which determines that it is currently only suitable for breaking conditions of small current levels, and is not suitable for breaking conditions of short-circuit current at the outlet of a super-large capacity generator. Summary of the invention

[0004] The technical problem to be solved by the present invention is how to improve the reliability of ultra-large short-circuit current interruption to meet the protection requirements of large generator sets.

[0005] The present invention solves the above technical problems through the following technical solutions: a large-capacity circuit breaker, the circuit breaker includes a main branch, a transfer branch, and a fuse branch, wherein the main branch includes a high-speed mechanical switch S, the transfer branch includes a transfer capacitor C, a transfer inductor L, and a thyristor module, the transfer capacitor C, the transfer inductor L, and the thyristor module are connected in series and then connected in parallel at both ends of the high-speed mechanical switch S, and the fuse branch includes at least one fuse F, and the fuse F is connected in parallel at both ends of the high-speed mechanical switch S.

[0006] The large-capacity circuit breaker of the present invention connects the transfer branch in parallel with the main branch and directly injects reverse current into the main branch through the transfer branch, so as to quickly reduce the current amplitude of the main branch, force the main branch current to drop rapidly and cross zero, and can quickly and reliably realize artificial zero crossing of the main branch, and finally complete the breaking through the fuse, thus greatly shortening the breaking time. The large-capacity circuit breaker is suitable for the breaking condition of the short-circuit current at the outlet of an ultra-large-capacity generator and is completely environmentally friendly.

[0007] Preferably, the high-speed mechanical switch S includes a combination of one or more of a vacuum switch, an air switch, and a power electronic switch.

[0008] Preferably, the high-speed mechanical switch S is driven by a fast operating mechanism, and the fast operating mechanism is a spring operating mechanism, a high-speed motor mechanism, or an electromagnetic repulsion mechanism.

[0009] Preferably, the transfer capacitor C is a pre-charging capacitor, the negative electrode of the transfer capacitor C is connected to one end of the high-speed mechanical switch S, the positive electrode of the transfer capacitor C is connected to one end of the transfer inductor L, the other end of the transfer inductor L is connected to one end of the thyristor module, and the other end of the thyristor module is connected to the other end of the high-speed mechanical switch S.

[0010] Preferably, the thyristor module includes a thyristor assembly T1 and a thyristor assembly T2 connected in reverse parallel, the cathode of the thyristor assembly T1 is connected to the anode of the thyristor assembly T2 and then connected to the other end of the transfer inductor L, and the anode of the thyristor assembly T1 is connected to the cathode of the thyristor assembly T2 and then connected to the other end of the high-speed mechanical switch S.

[0011] Preferably, the thyristor assembly T1 and the thyristor assembly T2 respectively include a plurality of thyristors connected in series.

[0012] Preferably, the fuse branch includes a single-pole double-throw switch and two parallel fuses. The two parallel fuses are switched by the single-pole double-throw switch, and after completing one current breaking, they are switched to another fuse.

[0013] Preferably, the circuit breaker further comprises a zinc oxide arrester, and the zinc oxide arrester is connected in parallel to both ends of the high-speed mechanical switch S.

[0014] Preferably, the forward breaking of the circuit breaker includes a normal current flow stage, an arcing and current transfer stage, and a current successful breaking stage. In the normal current flow stage, the current flows into the left end of the circuit breaker and flows out from the right end after passing through the high-speed mechanical switch S. At this time, no current flows through the transfer branch and the fuse branch. When a fault occurs, the high-speed mechanical switch S receives a trip signal, the high-speed mechanical switch S operates, and an arc is generated under the action of the current. When it is detected that the short-circuit current drops to a characteristic value, the thyristor component T2 is triggered, and the transfer capacitor C and the transfer inductor L oscillate to generate a high-frequency transfer current. The transfer current is injected into the main branch, causing the current flowing through the high-speed mechanical switch S to drop rapidly, generating an artificial zero crossing point, and the high-speed mechanical switch S is cut off after zero crossing, successfully withstanding the dielectric recovery voltage after the arc, and the short-circuit current begins to transfer to the fuse branch. As the thyristor component T2 is cut off after zero crossing, the short-circuit current is completely transferred to the fuse branch, the fuse of the fuse blows, and the fault current is successfully broken.

[0015] Preferably, the reverse breaking of the circuit breaker includes a normal current flow stage, an arcing and current transfer stage, and a current successful breaking stage. In the normal current flow stage, the current flows in from the right end of the circuit breaker and flows out from the left end after passing through the high-speed mechanical switch S. At this time, no current flows through the transfer branch and the fuse branch. When a fault occurs, the thyristor T2 is triggered in advance to release a half-cycle transfer current, and the polarity of the transfer capacitor C is reversed to positive on the left and negative on the right. The high-speed mechanical switch S receives the opening signal, and the high-speed mechanical switch S is actuated. Under the action of the current An arc is generated. When it is detected that the short-circuit current drops to a characteristic value, the thyristor component T1 is triggered, and the transfer capacitor C and the transfer inductor L oscillate to generate a high-frequency transfer current. The transfer current is injected into the main branch, causing the current flowing through the high-speed mechanical switch S to drop rapidly, generating an artificial zero crossing point. The high-speed mechanical switch S crosses zero and is cut off, successfully withstanding the post-arc dielectric recovery voltage. The short-circuit current begins to transfer to the fuse branch. As the thyristor component T1 crosses zero and is cut off, the short-circuit current is completely transferred to the fuse branch, the fuse of the fuse blows, and the fault current is successfully disconnected.

[0016] The advantages provided by the present invention are:

[0017] (1) The large-capacity circuit breaker of the present invention connects the transfer branch in parallel with the main branch and directly injects reverse current into the main branch through the transfer branch, which can quickly reduce the current amplitude of the main branch, force the main branch current to drop rapidly and cross zero, and can quickly and reliably realize the artificial zero crossing of the main branch. Finally, the circuit breaker is opened by the fuse, which greatly shortens the opening time. The circuit breaker is suitable for the opening and closing conditions of the short-circuit current of the ultra-large-capacity generator outlet and is completely environmentally friendly.

[0018] (2) The present invention configures the fuse branch to include a single-pole double-throw switch and two parallel fuses. The two parallel fuses are switched by the single-pole double-throw switch. After completing one current interruption, they can be quickly switched to another fuse, which helps the power system to quickly restore power supply.

[0019] (3) The present invention can suppress and absorb the overvoltage and energy generated during the fuse blowing process by connecting zinc oxide arresters in parallel at both ends of the high-speed mechanical switch S, thereby preventing the high-speed mechanical switch from reigniting after arcing. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A topological diagram of a large-capacity circuit breaker provided by an embodiment of the present invention;

[0021] Figure 2 A schematic diagram of a large-capacity circuit breaker in a normal current flow stage provided by an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of a large-capacity circuit breaker in arcing and current transfer stages provided by an embodiment of the present invention;

[0023] Figure 4 A schematic diagram of a large-capacity circuit breaker in arcing and current transfer stages provided by an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of a large-capacity circuit breaker provided by an embodiment of the present invention during a successful current breaking stage;

[0025] Figure 6 Another topological diagram of a large-capacity circuit breaker provided by an embodiment of the present invention;

[0026] Figure 7 Another topological diagram of a large-capacity circuit breaker provided by an embodiment of the present invention;

[0027] Figure 8 Another topological diagram of a large-capacity circuit breaker provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the technical solution of the present invention is clearly and completely described below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are 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.

[0029] like Figure 1As shown, this embodiment provides a large-capacity circuit breaker, including a main branch, a transfer branch, and a fuse branch, wherein the main branch includes a high-speed mechanical switch S, the transfer branch includes a transfer capacitor C, a transfer inductor L, and a thyristor module, the transfer capacitor C, the transfer inductor L, and the thyristor module are connected in series and then connected in parallel at both ends of the high-speed mechanical switch S, and the fuse branch includes at least one fuse F, and the fuse F is connected in parallel at both ends of the high-speed mechanical switch S.

[0030] The transfer capacitor C is a pre-charge capacitor. The thyristor module includes a thyristor assembly T1 and a thyristor assembly T2 connected in reverse parallel. The negative electrode of the transfer capacitor C is connected to one end of the high-speed mechanical switch S, the positive electrode of the transfer capacitor C is connected to one end of the transfer inductor L, the cathode of the thyristor assembly T1 is connected to the anode of the thyristor assembly T2 and then connected to the other end of the transfer inductor L, and the anode of the thyristor assembly T1 is connected to the cathode of the thyristor assembly T2 and then connected to the other end of the high-speed mechanical switch S.

[0031] The thyristor assembly T1 and the thyristor assembly T2 each include a plurality of thyristors connected in series.

[0032] Working principle: The large-capacity circuit breaker of the present invention can realize bidirectional breaking. The working process of the circuit breaker of the present invention is introduced below with forward breaking. The forward breaking of the circuit breaker includes the normal current flow stage, the arc burning and current transfer stage, and the current successful breaking stage. In the normal current flow stage, Figure 2 As shown in the figure, the current flows into the left end of the circuit breaker and flows out from the right end after passing through the high-speed mechanical switch S. At this time, no current flows through the transfer branch and the fuse branch. Figure 3 As shown, when the control system detects a fault state, the control system sends a trip signal to the high-speed mechanical switch S. The high-speed mechanical switch S receives the trip signal, and the high-speed mechanical switch S operates to generate an arc under the action of the current. When the control system detects that the short-circuit current drops to a characteristic value, the thyristor component T2 is triggered, and the transfer capacitor C and the transfer inductor L oscillate to generate a high-frequency transfer current. The transfer current is injected into the main branch, causing the current flowing through the high-speed mechanical switch S to drop rapidly, generating an artificial zero crossing point. The high-speed mechanical switch S is cut off at zero crossing and successfully withstands the post-arc dielectric recovery voltage, as shown in FIG. Figure 4 As shown, the short-circuit current begins to transfer to the fuse branch. As the thyristor component T2 crosses zero and is cut off, the short-circuit current is completely transferred to the fuse branch. Figure 5 As shown, the fuse of the fuse is blown and the fault current is successfully interrupted.

[0033] Similarly, when the circuit breaker is reversely opened, it still includes the normal current flow stage, the arcing and current transfer stage, and the current successful breaking stage. In the normal current flow stage, the current flows in from the right end of the circuit breaker and flows out from the left end after passing through the high-speed mechanical switch S. At this time, no current flows through the transfer branch and the fuse branch. At this time, the pre-charge polarity of the transfer capacitor C is still negative on the left and positive on the right. The transfer current generated after the thyristor component is triggered cannot force the high-speed mechanical switch S to generate an artificial zero crossing point. Therefore, when a fault occurs, the thyristor T2 is triggered in advance to release a half-cycle transfer current, and the polarity of the transfer capacitor C is reversed to positive on the left and negative on the right. The high-speed mechanical switch S receives the trip signal, and the high-speed mechanical switch S operates, generating an arc under the action of the current. When it is detected that the short-circuit current drops to the characteristic value, the thyristor component T1 is triggered, and the transfer capacitor C and the transfer inductor L oscillate to generate a high-frequency transfer current. The transfer current is injected into the main branch, causing the current flowing through the high-speed mechanical switch S to drop rapidly, generating an artificial zero crossing point. The high-speed mechanical switch S crosses zero and is cut off, successfully withstanding the post-arc dielectric recovery voltage, and the short-circuit current begins to transfer to the fuse branch. As the thyristor component T1 crosses zero and is cut off, the short-circuit current is completely transferred to the fuse branch, the fuse of the fuse blows, and the fault current is successfully disconnected.

[0034] Traditional sulfur hexafluoride circuit breakers need to wait for one or more natural zero crossings to complete current interruption, with a long interruption time and high arc energy accumulation, which reduces the reliability of interruption. The large-capacity circuit breaker of the present invention connects the transfer branch in parallel with the main branch and directly injects reverse current into the main branch through the transfer branch. It can quickly reduce the current amplitude of the main branch, forcing the main branch current to drop and cross zero quickly, and can quickly and reliably achieve artificial zero crossing of the main branch. Finally, the interruption is completed through the fuse, which greatly shortens the interruption time. It is suitable for the interruption condition of the short-circuit current of the ultra-large capacity generator outlet and is completely environmentally friendly.

[0035] The high-speed mechanical switch S includes a combination of one or more of a vacuum switch, an air switch, and a power electronic switch. The high-speed mechanical switch S is driven by a fast operating mechanism, which is a spring operating mechanism, a high-speed motor mechanism, or an electromagnetic repulsion mechanism. Figure 6 As shown, the high-speed mechanical switch S adopts a fast vacuum switch, which cooperates with the transfer branch and the fuse branch to complete the large-capacity current breaking.

[0036] like Figure 7 As shown, the fuse branch includes a single-pole double-throw switch and two parallel fuses. The two parallel fuses are switched by the single-pole double-throw switch. After completing one current interruption, they can be quickly switched to another fuse, which helps the power system to quickly restore power supply.

[0037] like Figure 8As shown, the circuit breaker also includes a zinc oxide lightning arrester, which is connected in parallel at both ends of the high-speed mechanical switch S, and can suppress and absorb the overvoltage and energy generated during the fuse blowing process to prevent the high-speed mechanical switch from reigniting after the arc.

[0038] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A large capacity circuit breaker, characterized in that: The circuit breaker includes a main branch, a transfer branch, and a fuse branch, wherein the main branch includes a high-speed mechanical switch S, the transfer branch includes a transfer capacitor C, a transfer inductor L, and a thyristor module, the transfer capacitor C, the transfer inductor L, and the thyristor module are connected in series and then connected in parallel at both ends of the high-speed mechanical switch S, and the fuse branch includes at least one fuse F, and the fuse F is connected in parallel at both ends of the high-speed mechanical switch S.

2. The large-capacity circuit breaker according to claim 1, characterized in that: The high-speed mechanical switch S includes a combination of one or more of a vacuum switch, an air switch, and a power electronic switch.

3. The large capacity circuit breaker according to claim 1 or 2, characterized in that: The high-speed mechanical switch S is driven by a fast operating mechanism, which is a spring operating mechanism, a high-speed motor mechanism, or an electromagnetic repulsion mechanism.

4. The large capacity circuit breaker according to claim 1, characterized in that: The transfer capacitor C is a pre-charge capacitor, the negative electrode of the transfer capacitor C is connected to one end of the high-speed mechanical switch S, the positive electrode of the transfer capacitor C is connected to one end of the transfer inductor L, the other end of the transfer inductor L is connected to one end of the thyristor module, and the other end of the thyristor module is connected to the other end of the high-speed mechanical switch S.

5. The large capacity circuit breaker according to claim 4, characterized in that: The thyristor module includes a thyristor assembly T1 and a thyristor assembly T2 connected in reverse parallel. The cathode of the thyristor assembly T1 is connected to the anode of the thyristor assembly T2 and then connected to the other end of the transfer inductor L. The anode of the thyristor assembly T1 is connected to the cathode of the thyristor assembly T2 and then connected to the other end of the high-speed mechanical switch S.

6. The large capacity circuit breaker according to claim 5, characterized in that: The thyristor assembly T1 and the thyristor assembly T2 respectively include a plurality of thyristors connected in series.

7. The large capacity circuit breaker according to claim 1, characterized in that: The fuse branch includes a single-pole double-throw switch and two parallel fuses. The two parallel fuses are switched by the single-pole double-throw switch, and after completing one current breaking, they are switched to another fuse.

8. The large capacity circuit breaker according to claim 1, characterized in that: The circuit breaker further comprises a zinc oxide lightning arrester, which is connected in parallel to both ends of the high-speed mechanical switch S.

9. The large capacity circuit breaker according to claim 4, characterized in that: The forward breaking of the circuit breaker includes a normal current flow stage, an arcing and current transfer stage, and a current successful breaking stage. In the normal current flow stage, the current flows into the left end of the circuit breaker and flows out from the right end after passing through the high-speed mechanical switch S. At this time, no current flows through the transfer branch and the fuse branch. When a fault occurs, the high-speed mechanical switch S receives a trip signal, and the high-speed mechanical switch S operates to generate an arc under the action of the current. When it is detected that the short-circuit current drops to a characteristic value, the thyristor component T2 is triggered, and the transfer capacitor C and the transfer inductor L oscillate to generate a high-frequency transfer current. The transfer current is injected into the main branch, causing the current flowing through the high-speed mechanical switch S to drop rapidly, generating an artificial zero crossing point. The high-speed mechanical switch S crosses zero and is cut off, successfully withstanding the dielectric recovery voltage after the arc, and the short-circuit current begins to transfer to the fuse branch. As the thyristor component T2 crosses zero and is cut off, the short-circuit current is completely transferred to the fuse branch, the fuse of the fuse blows, and the fault current is successfully broken.

10. The large capacity circuit breaker according to claim 4, characterized in that: The reverse breaking of the circuit breaker includes a normal current flow stage, an arcing and current transfer stage, and a current successful breaking stage. In the normal current flow stage, the current flows in from the right end of the circuit breaker and flows out from the left end after passing through the high-speed mechanical switch S. At this time, no current flows through the transfer branch and the fuse branch. When a fault occurs, the thyristor T2 is triggered in advance to release a half-cycle transfer current, and the polarity of the transfer capacitor C is reversed to positive on the left and negative on the right. The high-speed mechanical switch S receives the opening signal, and the high-speed mechanical switch S operates, generating a Arc, when it is detected that the short-circuit current drops to the characteristic value, the thyristor component T1 is triggered, and the transfer capacitor C and the transfer inductor L oscillate to generate a high-frequency transfer current. The transfer current is injected into the main branch, causing the current flowing through the high-speed mechanical switch S to drop rapidly, generating an artificial zero crossing point. The high-speed mechanical switch S crosses zero and is cut off, successfully withstanding the post-arc dielectric recovery voltage. The short-circuit current begins to transfer to the fuse branch. As the thyristor component T1 crosses zero and is cut off, the short-circuit current is completely transferred to the fuse branch, the fuse of the fuse blows, and the fault current is successfully disconnected.

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