A circuit breaker suitable for low-frequency power transmission and its breaking control method and device

Abstract

The present invention belongs to the technical field of circuit breakers, and specifically relates to a circuit breaker suitable for low-frequency power transmission and its breaking control method and device. The circuit breaker suitable for low-frequency power transmission includes N breaking units connected in series, N≥2, and the breaking control method first controls the first breaking unit to be disconnected after a current fault occurs; then controls the kth breaking unit to be delayed when it is disconnected, and controls the k+1th breaking unit to be disconnected at the end of the delay time, k=1,2,……,N‑1, so that the current zero point is within the arcing interval of the first breaking unit, the second breaking unit,……, or the Nth breaking unit. In the present invention, each breaking unit cooperates with the first and second actions to break the fault current, which can not only increase the breaking interval, cover the breaking of a large interval of low-frequency fault current, but also further improve the breaking current capacity, ensure the removal of the fault current during low-frequency power transmission, and enable the circuit breaker to have a long arcing breaking capability.

Description

Technical Field

[0001] The present invention belongs to the technical field of circuit breakers, and in particular relates to a circuit breaker suitable for low-frequency power transmission and a breaking control method and device thereof. Background Art

[0002] Conventional 50Hz AC transmission capacity is limited by distance, reactive power compensation is large, loss is large, and transmission efficiency is low; DC transmission involves AC / DC conversion, complex structure, difficulty in fault current interruption, and high cost. Based on the above, a low-frequency transmission method is proposed, which is more economical and efficient. However, the current zero-crossing period of this transmission method is long, such as 1 / 3 50Hz, whose period is increased from 20ms to 60ms, but conventional circuit breakers do not have the ability to interrupt long arcs, making it impossible to cut off the fault current. Summary of the invention

[0003] The present invention provides a circuit breaker suitable for low-frequency power transmission, a breaking control method suitable for the circuit breaker for low-frequency power transmission, and a breaking control device suitable for the circuit breaker for low-frequency power transmission, so as to solve the problem that conventional circuit breakers cannot cut off fault current when using low-frequency power transmission.

[0004] In order to solve the above technical problems, the technical solutions included in the present invention and the beneficial effects corresponding to the technical solutions are as follows:

[0005] The present invention provides a breaking control method for a circuit breaker for low-frequency power transmission, wherein the circuit breaker for low-frequency power transmission comprises N breaking units connected in series, where N≥2, and the breaking control method comprises the following steps:

[0006] After a current fault occurs, the first breaking unit is controlled to disconnect;

[0007] Controlling the kth breaking unit to be disconnected for a delay, and controlling the k+1th breaking unit to be disconnected when the delay time ends, k=1, 2, ..., N-1, so that the current zero-crossing point is within the arcing interval of the first breaking unit, the second breaking unit, ..., or the Nth breaking unit;

[0008] The delay time is less than or equal to the duration corresponding to the arcing interval of each breaking unit.

[0009] The beneficial effects of the above technical solution are as follows: the present invention applies a circuit breaker including a plurality of breaking units arranged in series to low-frequency power transmission, and each breaking unit cooperates to act first or later to break the fault current, which can not only increase the breaking interval and cover the breaking of a large range of low-frequency fault current, but also the breaking current capacity is not lower than that of a conventional circuit breaker, so that the breaking current capacity is further improved, ensuring the removal of the fault current during low-frequency power transmission, and enabling the circuit breaker to have a long arc breaking capability.

[0010] Furthermore, the duration corresponding to the arcing interval is the difference between the long arcing time of the breaking unit and the short arcing time of the breaking unit, the long arcing time is the longest arcing time that can be broken, and the short arcing time is the shortest arcing time that can be broken.

[0011] Furthermore, N=2.

[0012] Furthermore, the delay time is equal to the duration corresponding to the arcing interval of each breaking unit.

[0013] Furthermore, the duration corresponding to the arcing interval is greater than or equal to Δt A / N,△t A It is the circuit breaker whole machine time.

[0014] The present invention provides a breaking control device suitable for a circuit breaker for low-frequency power transmission, comprising a memory and a processor, wherein the processor is used to execute computer instructions stored in the memory to implement the above-mentioned breaking control method suitable for a circuit breaker for low-frequency power transmission, and achieve the same beneficial effects as the method.

[0015] The present invention provides a circuit breaker suitable for low-frequency power transmission, the circuit breaker suitable for low-frequency power transmission includes N breaking units connected in series, N≥2, and also includes a breaking control device suitable for the circuit breaker for low-frequency power transmission, the breaking control device includes a memory and a processor, the processor is used to execute computer instructions stored in the memory to implement the above-mentioned breaking control method suitable for low-frequency power transmission, and achieve the same beneficial effects as the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a timing diagram of the breaking control method of the present invention applicable to a circuit breaker for low-frequency power transmission;

[0017] Figure 2 It is a structural diagram of a breaking control device suitable for a circuit breaker for low-frequency power transmission according to the present invention. DETAILED DESCRIPTION

[0018] The basic concept of the present invention is: a circuit breaker composed of multiple breaking units connected in series, each breaking unit operates successively, covers a large range of low-frequency fault current, continuously breaks the current, and further improves the breaking current capacity. The following is a detailed description of a circuit breaker suitable for low-frequency power transmission, a breaking control method suitable for low-frequency power transmission, and a breaking control device suitable for low-frequency power transmission circuit breaker of the present invention in combination with the accompanying drawings and embodiments.

[0019] Applicable to the circuit breaker for low frequency power transmission embodiment:

[0020] An embodiment of a circuit breaker suitable for low-frequency power transmission of the present invention comprises two breaking units (the breaking units are conventional circuit breakers) arranged in series, namely a first breaking unit and a rear breaking unit, and the two breaking units have the same specifications, and also comprises a breaking control device suitable for the circuit breaker for low-frequency power transmission. The breaking control device suitable for the circuit breaker for low-frequency power transmission comprises a memory and a processor, and the processor is used to execute computer instructions in the memory to realize a breaking control method of the circuit breaker suitable for low-frequency power transmission of the present invention. The method is described in detail below.

[0021] Step 1: After a current fault occurs, an action signal is sent to the first-opening unit to control the first-opening unit to disconnect.

[0022] Step 2: Control the delay when the first-open unit is disconnected, the delay time t d , delay time t d At the end of the control, the rear opening unit is disconnected; among them, the delay time t d The duration △t corresponding to the arcing interval of the two breaking units p .

[0023] Among them, the duration △t corresponding to the arcing interval of the breaking unit p It can be measured by testing, and the shortest arcing time that can be broken (i.e. the short arcing time of the breaking unit) t can be found by conducting a breaking test on the breaking unit. arc min and the longest arcing time that can be interrupted (i.e. the long arcing time of the interrupting unit) t arc max The difference between the two is △t p , the value shall not be less than △t A / N,△t A It is the circuit breaker whole machine time.

[0024] like Figure 1 As shown in the figure, this method makes it possible that: if the current zero-crossing point appears in the arcing interval of the first-opening unit, the first-opening unit cuts off the fault current, and the subsequent opening unit no longer needs to break the fault current; if the current zero-crossing point is not in the arcing interval of the first-opening unit, it will appear in the arcing interval of the subsequent opening unit. At this time, the first-opening breaking unit only arcs, and the subsequent opening unit realizes fault current breaking. The overall breaking capacity of the circuit breaker can cover the full breaking interval of the low-frequency transmission fault current.

[0025] In this embodiment, the delay time t d The duration △t corresponding to the arcing interval of the two breaking units p , so that the arcing interval of the entire circuit breaker includes the arcing interval of two complete opening units, so that the breaking interval of the entire circuit breaker is maximized. However, this is a more ideal situation. In order to avoid gaps, the delay time t can be set dAppropriately smaller than the duration △t corresponding to the arcing interval p , but should still be greater than or equal to △t A / N.

[0026] In this embodiment, the circuit breaker includes two disconnecting units arranged in series. Without considering economic issues, the circuit breaker may include multiple (more than two) disconnecting units to greatly increase the arcing interval of the circuit breaker and further improve the disconnecting current capacity. For example, the circuit breaker may include three disconnecting units arranged in series, namely the first disconnecting unit, the second disconnecting unit and the third disconnecting unit. After a current fault occurs, the first disconnecting unit is first controlled to disconnect, and the delay t d Then the second breaking unit is controlled to disconnect, and then the delay t d Then the third breaking unit is controlled to be disconnected, that is, the control rule is: delay is performed when controlling the kth breaking unit to be disconnected, and when the delay time is over, the k+1th breaking unit is controlled to be disconnected, so that the arcing interval of the entire circuit breaker includes the arcing intervals of three complete opening units.

[0027] Embodiment of the breaking control method applicable to a circuit breaker for low-frequency power transmission:

[0028] In an embodiment of a method for controlling the breaking of a circuit breaker for low-frequency power transmission according to the present invention, for a controller including two breaking units arranged in series, the circuit breaker is controlled to break by using the same method as the method for controlling the breaking of a circuit breaker for low-frequency power transmission introduced in the embodiment of the circuit breaker for low-frequency power transmission. The control timing diagram is shown in FIG. Figure 1 Since the method is described in detail in the embodiment applicable to the circuit breaker for low-frequency power transmission, it will not be described here in detail.

[0029] Embodiment of the breaking control device applicable to the circuit breaker for low-frequency power transmission:

[0030] An embodiment of a breaking control device for a circuit breaker for low-frequency power transmission according to the present invention is as follows: Figure 2 As shown, it includes a memory, a processor and an internal bus, and the processor and the memory communicate and exchange data with each other through the internal bus. The memory includes at least one software function module stored in the memory, and the processor executes various functional applications and data processing by running the software program and module stored in the memory, thereby realizing a breaking control method for a circuit breaker for low-frequency power transmission introduced in the embodiment of the circuit breaker for low-frequency power transmission of the present invention.

[0031] The processor may be a microprocessor MCU, a programmable logic device FPGA or other processing device.

[0032] The memory may be various memories that use electrical energy to store information, such as RAM, ROM, etc.; it may also be various memories that use magnetic energy to store information, such as hard disks, floppy disks, magnetic tapes, magnetic core memories, bubble memories, USB flash drives, etc.; it may also be various memories that use optical methods to store information, such as CDs, DVDs, etc.; of course, it may also be other types of memories, such as quantum memories, graphene memories, etc.

Claims

1. A method for controlling the breaking of a circuit breaker for low-frequency power transmission, characterized in that: The circuit breaker for low-frequency power transmission comprises N breaking units connected in series, N≥2, and the breaking control method comprises the following steps: After a current fault occurs, the first breaking unit is controlled to be disconnected; starting from the second breaking unit, each breaking unit is controlled in sequence as follows: a delay is performed when the previous breaking unit is disconnected, and the next breaking unit is disconnected at the end of the delay, until the current zero crossing point is within the arcing interval of the previous breaking unit, and the next breaking unit is disconnected without delay; the previous breaking unit and the next breaking unit are two adjacent breaking units in order; The delay time is less than or equal to the duration corresponding to the arcing interval of each breaking unit.

2. The breaking control method for a circuit breaker for low-frequency power transmission according to claim 1, characterized in that: The duration corresponding to the arcing interval is the difference between the long arcing time of the breaking unit and the short arcing time of the breaking unit, the long arcing time is the longest arcing time that can be broken, and the short arcing time is the shortest arcing time that can be broken.

3. The breaking control method for a circuit breaker for low-frequency power transmission according to claim 1 or 2, characterized in that: N=2。 4. The breaking control method for a circuit breaker for low-frequency power transmission according to claim 1 or 2, characterized in that: The delay time is equal to the duration corresponding to the arcing interval of each breaking unit.

5. The breaking control method for a circuit breaker for low-frequency power transmission according to claim 1, characterized in that: The duration corresponding to the arcing interval is greater than or equal to △t A / N,△t A It is the circuit breaker whole machine time.

6. A breaking control device suitable for a circuit breaker for low-frequency power transmission, characterized in that: It comprises a memory and a processor, wherein the processor is used to execute computer instructions stored in the memory to implement the breaking control method for a circuit breaker for low-frequency power transmission as described in any one of claims 1 to 5.

7. A circuit breaker suitable for low-frequency power transmission, characterized in that: The circuit breaker suitable for low-frequency power transmission includes N breaking units connected in series, N≥2, and also includes a breaking control device suitable for the circuit breaker for low-frequency power transmission. The breaking control device includes a memory and a processor, and the processor is used to execute computer instructions stored in the memory to implement the breaking control method suitable for the circuit breaker for low-frequency power transmission as described in any one of claims 1 to 5.

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