Natural commutation type direct-current circuit breaker based on self-excitation blow-out

Abstract

The invention provides a natural commutation type direct-current circuit breaker based on self-excitation blow-out. The natural commutation type direct-current circuit breaker comprises a main through-flow branch and a transfer branch which are connected in parallel, the main through-flow branch comprises a plurality of gas arc extinguish chambers and vacuum arc extinguish chambers which are connected in series, and the gas arc extinguish chambers, the vacuum arc extinguish chambers and corresponding operating mechanisms form a rapid mechanical switch; the transfer branch comprises a magnet exciting coil and a plurality of bidirectional fixed switch modules which are arranged in series, the magnet exciting coil is arranged in the gas arc-extinguishing chamber, and when the magnet exciting coil passes through current, a generated magnetic field can lengthen the arc length of an electric arc generated in the gas arc-extinguishing chamber. After an opening instruction is received, contacts in the vacuum arc-extinguishing chamber and the gas arc-extinguishing chamber are separated to generate an electric arc, electric arc voltage drives current to be converted from the main through-flow branch to the transfer branch, and the current flows through the magnet exciting coil, so that the electric arc is magnetically blown out, the arc length of the electric arc is lengthened, and the electric arc voltage is improved; and the driving current is transferred from the main through-current branch to the transfer branch more quickly, so that the current can be converted quickly and naturally.

Description

Technical Field

[0001] The present disclosure relates to the field of direct current circuit breakers, and in particular to a naturally commutated direct current circuit breaker based on self-excitation blowing. Background Art

[0002] The flexible DC grid has a more complex and diverse system main wiring structure and operation mode, which leads to multiple fault modes, rapid fault development and wide impact range. Therefore, there is an urgent need for fault isolation technology for flexible DC grid to ensure the safe and reliable operation of flexible DC grid. DC circuit breaker is the most ideal choice for DC fault isolation in DC transmission and distribution system.

[0003] Due to the low impedance characteristics of the flexible DC grid, the fault current rise rate is high, which puts extremely high requirements on the breaking speed of the DC circuit breaker. The solid-state circuit breaker with a fast breaking speed has a large on-state loss, so hybrid DC circuit breakers are widely used in engineering. At present, when the fault current rise rate is high and the fault current is large, it is difficult for the hybrid DC circuit breaker to transfer the current from the main flow branch to the transfer branch. Forced commutation is often used in engineering, but there are many components and the control is more complicated, and there is a problem of insufficient reliability. The natural commutation DC circuit breaker uses arc voltage to transfer the current from the main flow branch to the transfer branch. It is the lowest cost and simplest commutation method of the hybrid DC circuit breaker, but the vacuum breaker arc voltage commonly used in the DC circuit breaker is low, usually not exceeding 30V, and its transfer speed is slow and the transfer reliability is low, which is difficult to meet the large-capacity short-circuit breaking requirements of the DC system. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a natural commutation DC circuit breaker based on self-excitation blowing, which increases the arc voltage of the gas arc by connecting an excitation coil in series with the transfer branch to generate a self-excitation magnetic field, thereby achieving fast and reliable natural commutation. Compared with the existing hybrid DC circuit breaker, it has the advantages of low cost, compact size and high reliability.

[0005] The present disclosure is preferably implemented by the following scheme:

[0006] A natural commutation DC circuit breaker based on self-excitation blowing, comprising a parallel main current branch and a transfer branch;

[0007] The main current branch includes a plurality of gas arc extinguishing chambers and vacuum arc extinguishing chambers arranged in series, and the gas arc extinguishing chambers and vacuum arc extinguishing chambers and corresponding operating mechanisms form a fast mechanical switch;

[0008] The transfer branch includes an excitation coil and a plurality of bidirectional fixed switch modules arranged in series, wherein the excitation coil is arranged in the gas arc extinguishing chamber, and when the excitation coil is energized, the magnetic field generated can lengthen the arc length of the arc generated by the fast mechanical switch in the gas arc extinguishing chamber.

[0009] Furthermore, the gas in the gas arc extinguishing chamber includes one or more of hydrogen, helium, nitrogen, carbon dioxide and sulfur hexafluoride.

[0010] Furthermore, the contact of the fast mechanical switch is a cup-shaped flat plate contact, a non-cup-shaped flat plate contact and a non-cup-shaped plug-in contact.

[0011] Furthermore, the bidirectional fixed switch module includes a buffer circuit, a bidirectional switch circuit and a voltage limiting circuit connected in parallel; the buffer circuit is an RC circuit; the bidirectional switch circuit is a controllable switch element with an anti-series diode; and the voltage limiting circuit is a voltage limiting resistor or a metal oxide varistor.

[0012] Furthermore, the input end of the controllable switch element is connected to the positive poles of the two anti-series diodes, and the output end of the controllable switch element is connected to the negative poles of the two anti-series diodes. Other topologies that can also achieve bidirectional flow can also be used according to requirements.

[0013] Furthermore, the controllable switch element is an insulated gate bipolar transistor, an integrated gate commutated thyristor or a gate injection enhancement transistor.

[0014] Furthermore, it also includes an energy dissipation branch composed of metal oxide varistors.

[0015] The beneficial effects of the above technical solution provided by the embodiments of the present disclosure include at least:

[0016] After receiving the opening command, the contacts of the fast mechanical switch in the vacuum arc extinguishing chamber and the gas arc extinguishing chamber are separated to generate an arc. The arc voltage drives the current to commutate from the main current branch to the transfer branch. After the current flows through the excitation coil, the arc is magnetically blown, which lengthens the arc length and drives the current to transfer from the main current branch to the transfer branch more quickly, enabling rapid natural commutation. When the current of the fast mechanical switch passes through zero, the contacts extinguish the arc, and the contacts of the fast mechanical switch continue to make the opening movement. After the contact gap can withstand the system transient recovery voltage, the bidirectional solid-state switch module is turned off, and the fault current is transferred to the energy dissipation branch. The voltage between the DC circuit breaker terminals is limited by the energy absorption branch, and the fault current gradually drops to zero.

[0017] Other features and advantages of the present disclosure will be described in the following description or understood by practicing the present invention. The purpose and other advantages of the present disclosure can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0018] The technical solution of the present disclosure is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present disclosure and do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0020] Figure 1 A topological structure diagram of a naturally commutated DC circuit breaker based on self-excitation blowing in an embodiment of the present disclosure;

[0021] Figure 2 It is a schematic diagram of the magnetic blowing of the arc exciting coil when the fast mechanical switch contacts of the naturally commutated DC circuit breaker based on self-excitation blowing in the embodiment of the present disclosure are separated; DETAILED DESCRIPTION

[0022] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0023] In order to solve the problems existing in the prior art, the present disclosure provides a natural commutation DC circuit breaker based on self-excitation blowing, and its topology structure is as follows: Figure 1 As shown, it includes a main flow branch and a transfer branch connected in parallel.

[0024] The main current branch includes a plurality of gas arc extinguishing chambers and vacuum arc extinguishing chambers arranged in series, and the gas arc extinguishing chambers and vacuum arc extinguishing chambers and the corresponding operating mechanisms constitute a fast mechanical switch. Optionally, the gas in the gas arc extinguishing chamber includes one or more of hydrogen, helium, nitrogen, carbon dioxide and sulfur hexafluoride. Optionally, the operating mechanism may adopt an electromagnetic repulsion operating mechanism, a permanent magnet operating mechanism or a spring operating mechanism. Optionally, the contact of the fast mechanical switch is a cup-shaped flat plate contact, a non-cup-shaped flat plate contact and a non-cup-shaped plug-in contact. For the flat plate contact or plug-in contact of the non-cup-shaped contact, the design ideas and methods in the embodiment of the present disclosure can also be adopted. The transfer branch includes an excitation coil B and a plurality of bidirectional fixed switch modules arranged in series, wherein the excitation coil is arranged in the gas arc extinguishing chamber, and when the excitation coil is flowing, the magnetic field generated can lengthen the arc length of the arc generated by the fast mechanical switch in the gas arc extinguishing chamber.

[0025] Optionally, the bidirectional fixed switch module includes a buffer circuit, a bidirectional switch circuit and a voltage limiting circuit connected in parallel. The buffer circuit is an RC circuit; the bidirectional switch circuit is a controllable switch element PES with an anti-series diode; the voltage limiting circuit is a voltage limiting resistor, or an energy dissipation branch metal oxide varistor (MOV).

[0026] As a preferred embodiment, the input end of the controllable switch element PES is connected to the positive poles of two anti-series diodes, and the output end of the controllable switch element PES is connected to the negative poles of two anti-series diodes. That is, the bidirectional solid-state switch module is a diode anti-series full-bridge structure. Other topologies that can also achieve bidirectional flow can also be used according to requirements.

[0027] Optionally, the controllable switch element PES is an insulated gate bipolar transistor.

[0028] Optionally, the controllable switch element PES is an integrated gate-commutated thyristor.

[0029] Optionally, the controllable switch element PES is a gate injection enhancement transistor. Further, the self-excited blowing-based natural commutation DC circuit breaker disclosed in the present invention also includes an energy dissipation branch. The energy dissipation branch preferably includes a metal oxide varistor.

[0030] See also Figure 1 and Figure 2As shown, after receiving the opening command, the DC circuit breaker in the embodiment of the present disclosure uses the moving contact and the static contact of the fast mechanical switch in the gas arc extinguishing chamber to separate to generate an arc, and the arc voltage drives the current to commutate from the main flow branch to the transfer branch. After the current flows through the excitation coil, the arc is magnetically blown, which lengthens the arc length, and drives the current to transfer from the main flow branch to the transfer branch more quickly, so that natural commutation can be achieved quickly. When the fast mechanical switch current I passes through zero, the contact extinguishes the arc, and the contact of the fast mechanical switch continues to make the opening movement. After the contact gap can withstand the system transient recovery voltage, the bidirectional solid-state switch module is turned off, and the fault current is transferred to the energy dissipation branch. The voltage between the DC circuit breaker terminals is limited by the energy absorption branch, and the fault current gradually drops to zero.

[0031] Unless otherwise stated, the "connection" mentioned above refers to a logical relationship of current transmission, and does not necessarily mean a direct electrical connection. At the same time, "first", "second", etc. do not indicate a sequence, but are only used to identify related units, devices, etc.

[0032] Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A naturally commutated DC circuit breaker based on self-excitation blowing, characterized in that: It includes parallel main flow branches and transfer branches; The main current branch includes a plurality of gas arc extinguishing chambers and vacuum arc extinguishing chambers arranged in series, and the gas arc extinguishing chambers and vacuum arc extinguishing chambers and corresponding operating mechanisms form a fast mechanical switch; The transfer branch includes an excitation coil and a plurality of bidirectional fixed switch modules arranged in series, wherein the excitation coil is arranged in the gas arc extinguishing chamber, and when the excitation coil is energized, the magnetic field generated can lengthen the arc length of the arc generated by the fast mechanical switch in the gas arc extinguishing chamber.

2. The naturally commutated DC circuit breaker based on self-excitation blowing according to claim 1, characterized in that: The gas in the gas arc extinguishing chamber includes one or more of hydrogen, helium, nitrogen, carbon dioxide and sulfur hexafluoride.

3. The naturally commutated DC circuit breaker based on self-excitation blowing according to claim 1, characterized in that: The contact of the fast mechanical switch is a cup-shaped flat plate contact, a non-cup-shaped flat plate contact and a non-cup-shaped plug-in contact.

4. The naturally commutated DC circuit breaker based on self-excitation blowing according to claim 1, characterized in that: The bidirectional solid-state switch module includes a buffer circuit, a bidirectional switch circuit and a voltage limiting circuit connected in parallel; the buffer circuit is an RC circuit; the bidirectional switch circuit is a controllable switch element with an anti-series diode; and the voltage limiting circuit is a voltage limiting resistor or a metal oxide varistor.

5. The naturally commutated DC circuit breaker based on self-excitation blowing as claimed in claim 4, characterized in that: The input end of the controllable switch element is connected to the anodes of the two anti-series diodes, and the output end of the controllable switch element is connected to the cathodes of the two anti-series diodes.

6. The naturally commutated DC circuit breaker based on self-excitation blowing as claimed in claim 5, characterized in that: The controllable switch element is an insulated gate bipolar transistor, an integrated gate commutated thyristor or a gate injection enhancement transistor.

7. The naturally commutated DC circuit breaker based on self-excitation blowing according to claim 1, characterized in that: An energy dissipation branch consisting of a metal oxide varistor is also included.

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