Direct-current circuit breaker with arc discharge detection function and control method thereof

Abstract

The invention provides a direct-current circuit breaker with an arc discharge detection function and a control method thereof, the direct-current circuit breaker comprises a solid-state circuit breaker and an arc discharge detection assembly connected with the solid-state circuit breaker, and the solid-state circuit breaker at least comprises a power electronic device branch, a mechanical switch or contactor, an energy absorption device, a power panel and a control panel, the mechanical switch or the contactor is connected in series on a main branch of the direct current circuit breaker, the power electronic device branch is connected in parallel with the mechanical switch or the contactor, the energy absorption device is connected with the power electronic device branch, and the control panel and the power panel are connected with the power electronic device branch, the mechanical switch or the contactor and the arc discharge detection assembly. An arc discharge detection function is added, so that an arc discharge fault can be disconnected more quickly and accurately; and by setting the branch conduction time of the power electronic device, the on-off time of the direct current circuit breaker is further shortened, safer protection is provided for the system, and the reliability and engineering practicability of the direct current system are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of power electronics, and in particular relates to a DC circuit breaker with an arc detection function and a control method thereof. Background Art

[0002] Circuit breakers can cover major application areas such as rail transit, new energy and ships. With the rise and application of DC networking technology in high-voltage transmission, medium and low voltage power distribution, new energy access, ship electric propulsion and other fields, higher requirements are put forward for the relay protection strategy, system intelligence, opening and closing speed, reliability and other aspects of the distribution system. The response speed of traditional mechanical circuit breaker equipment is difficult to cope with the rapid response requirements of systems with a high proportion of power electronic equipment. In this context, solid-state and hybrid high-speed switches will serve as a more ideal fault isolation method for direct current systems, and their application scenarios will be diversified and large-scale.

[0003] Since DC arcing may cause accidents, such as the DC side terminals of new energy photovoltaic systems, which are prone to arcing, how to solve the arc hazards has always been a problem of concern in the electrical industry. If the circuit can be quickly cut off when arcing occurs, it is one of the effective ways to avoid accidents such as fire. However, the common DC circuit breakers on the market do not have arcing detection function. In addition, during the opening and closing process of the solid-state DC circuit breaker, the conduction time of the electronic branch covers the entire shutdown process. Especially under fault current, the longer electronic branch conduction time will increase the probability of damage to electronic devices. Therefore, in order to further shorten the opening and closing time of the hybrid DC circuit breaker, it is necessary to set a new electronic branch conduction time to control the DC circuit breaker, and the existing control method requires that the electronic branch can only be disconnected after the mechanical switch is completely disconnected. Therefore, a variable delay DC circuit breaker electronic branch disconnection time control method is proposed. Summary of the invention

[0004] The present invention provides a DC circuit breaker with an arc detection function and a control method thereof, so as to solve the problems that the existing DC circuit breaker has no arc detection function, the system selectivity needs to be enhanced, and the fault is not accurately identified.

[0005] Based on the above purpose, an embodiment of the present invention provides a DC circuit breaker with an arc detection function, including: a solid-state circuit breaker and an arc detection component connected to the solid-state circuit breaker, the solid-state circuit breaker at least includes: a power electronic device branch, a mechanical switch or contactor, an energy absorption device, a power supply board and a control board, the mechanical switch or contactor is connected in series to the main branch of the DC circuit breaker, the power electronic device branch is connected in parallel to the mechanical switch or contactor branch, the energy absorption device is connected to the power electronic device branch, the control board is connected to the power electronic device branch and the mechanical switch or contactor branch. The power supply board is connected to the power electronic device branch, the mechanical switch or contactor, and the arc detection component.

[0006] Optionally, the arc detection component and the solid-state circuit breaker are independently provided, and the arc detection component is connected to the control board in the solid-state circuit breaker via wired or wireless communication.

[0007] Optionally, the arc detection component adopts a photomultiplier tube module or an arc feature extraction module.

[0008] Optionally, the arc detection component is arranged inside or outside the solid-state circuit breaker and is flexibly installed according to required installation and detection conditions.

[0009] Optionally, when the arc detection component is arranged outside, power is provided to the arc detection component by a power board or externally.

[0010] Optionally, the arc detection component includes: a drive module, an arc detection module and a signal processing module connected in sequence; after the arc detection component is powered on, the drive module drives the arc detection module to perform arc detection on the overall system environment where the DC circuit breaker where the solid-state circuit breaker is installed is installed, and when an arc is detected, the signal processing module outputs a first detection signal to the control board to execute the disconnecting operation of the solid-state circuit breaker, and simultaneously outputs a second detection signal to the overall system control circuit of the DC circuit breaker.

[0011] Optionally, a power electronic switch is provided in the power electronic device branch, and the energy absorption device is a metal oxide varistor module or a transient suppression diode module.

[0012] Based on the same inventive concept, an embodiment of the present invention also proposes a control method for a DC circuit breaker with an arc detection function, comprising: a control board receives a trip command or a first detection signal of arc detection transmitted by an arc detection component; the control board controls the power electronic device branch to be turned on, the mechanical switch to be turned off, or the contactor to be disconnected; the moment t when the mechanical switch or contactor just starts to disconnect is detected by the auxiliary contacts of the mechanical switch or contactor, and because the current size in the circuit has different requirements for the disconnection capacity, a coefficient k can be multiplied by the current value before disconnection to obtain a variable delay time t1; after the variable delay time t1, the control board turns off the power electronic device branch; when the energy storage element in the power electronic device branch reaches the action voltage of the energy absorption device, the energy absorption device is turned on, and the energy is consumed by the energy absorption device to complete the disconnection of the DC circuit breaker.

[0013] Optionally, the method also includes: verifying and controlling the arcing state of the system, including: the control board receives the first detection signal transmitted by the arc detection component that detects arcing; when the arcing state verification function is enabled, the power electronic device branch is turned on, the mechanical switch or contactor is disconnected, and after the mechanical switch or contactor is disconnected, the power electronic device branch is disconnected and remains in the disconnected state for a period of time, and then the power electronic device branch is turned on again; the control board records and saves the arc detection component detection signal during the three periods of time when the power electronic device branch is turned on, disconnected, and turned on again; if the arc detection signal does not change in a short period of time, it can be determined that the signal transmitted by the arcing component is a misjudgment; if it is determined to be a misjudgment, the power electronic device branch is kept turned on, the mechanical switch or contactor is closed, and after the mechanical switch or contactor is closed, the power electronic device branch is disconnected; if it is determined to be an arc, the power electronic device branch is disconnected.

[0014] Optionally, the calculation of the variable delay time t1 based on the current flow includes: obtaining the current before the mechanical switch or contactor is disconnected; and multiplying the current by a preset coefficient to obtain the variable delay time t1.

[0015] The beneficial effects of the present invention are as follows: as can be seen from the above, an embodiment of the present invention provides a DC circuit breaker with an arc detection function and a control method thereof, the DC circuit breaker comprising: a solid-state circuit breaker and an arc detection component connected to the solid-state circuit breaker, the solid-state circuit breaker at least comprising: a power electronic device branch, a mechanical switch or contactor, an energy absorption device, a power supply board and a control board, the mechanical switch or contactor is connected in series to the main branch of the DC circuit breaker, the power electronic device branch is connected to the mechanical switch or contactor in parallel, the energy absorption device is connected to the power electronic device branch, the control board and the power supply board are connected to the power electronic device branch, the mechanical switch or contactor and the arc detection component, by adding a solid-state circuit breaker with an arc detection function, the arc fault can be disconnected more quickly and accurately; the new control method is used to set the electronic branch conduction time, which further speeds up the breaking time of the DC circuit breaker and provides safer protection for the system. At the same time, the use of contactors instead of traditional fast mechanical switches can reduce costs and further improve the reliability and engineering practicality of the DC system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 Schematic diagram of the structure of a DC circuit breaker with arc detection function in an embodiment of the present invention;

[0018] Figure 2 It is a structural schematic diagram of a DC circuit breaker with an arc detection function in another embodiment of the present invention;

[0019] Figure 3 Schematic diagram of the structure of the arc detection assembly in an embodiment of the present invention;

[0020] Figure 4 It is a flowchart of a control method of a DC circuit breaker with an arc detection function in an embodiment of the present invention;

[0021] Figure 5 The figure is a schematic diagram of arc state verification of a control method for a DC circuit breaker with an arc detection function in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0023] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present invention should be understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the embodiments of the present invention do not represent any order, quantity or importance, but are only used to distinguish different components. "Including" or "comprising" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0024] The embodiment of the present invention provides a DC circuit breaker with an arc detection function. Figure 1 As shown, a DC circuit breaker with an arc detection function includes: a solid-state circuit breaker and an arc detection component connected to the solid-state circuit breaker. The solid-state circuit breaker includes at least: a power electronic device branch, a mechanical switch or contactor, an energy absorption device, a power supply board and a control board. The mechanical switch or contactor is connected in series to the main branch of the DC circuit breaker, the power electronic device branch is connected in parallel to the mechanical switch or contactor, the energy absorption device is connected to the power electronic device branch, and the control board is connected to the power electronic device branch and the mechanical switch or contactor. The power supply board is connected to the power electronic device branch, the mechanical switch or contactor, and the arc detection component.

[0025] A power electronic switch IGBT is provided in the power electronic device branch, and the energy absorption device is a metal oxide varistor (MOV) or a transient voltage suppressor (TVS) module. The arc detection component adopts a photomultiplier tube module or an arc feature extraction module. When a short circuit occurs in the DC system where the DC circuit breaker is located, a conduction pulse is first sent to the power electronic switch IGBT, and a mechanical switch opening command is issued at the same time. After a short delay, the mechanical switch starts to open, and the current is transferred to the power electronic switch. After the mechanical switch reaches the rated opening distance, the power electronic switch is turned off, and the voltage across the DC circuit breaker rises rapidly, reaching the action voltage of the energy absorption device, and the current is transferred to the energy absorption device. All the remaining inductive energy in the system is absorbed by the energy absorption device, and the short-circuit current begins to decrease.

[0026] When the control panel receives the system disconnection command or the solid-state circuit breaker detects a short circuit condition or the arc detection component detects an arc, it triggers a disconnection command to the mechanical switch or contactor, and triggers a conduction command to the power electronic device branch. The mechanical switch or contactor disconnects upon receiving the disconnection command, and the current is quickly transferred from the branch where the mechanical switch or contactor is located to the power electronic device branch and disconnected. The main function of the power electronic device branch is to disconnect the current during a short circuit fault as quickly as possible. When the voltage in the power electronic device branch reaches the action voltage of the energy absorption device, it is transferred to the energy absorption device for consumption, completing the disconnection.

[0027] In an embodiment of the present invention, the arc detection component and the solid-state circuit breaker can be independently provided, and the arc detection component is connected to the control board in the solid-state circuit breaker by wired or wireless communication. The arc detection component can be provided inside or outside the solid-state circuit breaker and can be flexibly installed according to the required installation and detection conditions. Figure 1 The arc detection component is arranged outside the solid-state circuit breaker, and the external power supply is provided to the arc detection component. Figure 2 The arc detection component is arranged inside the solid-state circuit breaker, and the arc detection component is electrically connected to the power board.

[0028] See also Figure 3 The arc detection component includes: a driving module, an arc detection module and a signal processing module connected in sequence; after the arc detection component is powered on, the control board outputs a driving signal to the driving module, and the driving module drives the arc detection module to perform arc detection on the overall system environment where the DC circuit breaker is installed, and when an arc is detected, the signal processing module outputs a first detection signal to the control board to execute the disconnection operation of the solid-state circuit breaker, and at the same time outputs a second detection signal to the overall system control circuit of the DC circuit breaker.

[0029] The DC circuit breaker with arc detection function in the embodiment of the present invention also has a system arc state verification control function. Specifically, it includes: the control board receives the first detection signal transmitted by the arc detection component to detect arc; when the arc state verification function is enabled, the control board controls the power electronic device branch to be turned on, the mechanical switch or contactor to be turned off, and after the mechanical switch or contactor is turned off, the power electronic device branch is turned off and kept in the disconnected state for a period of time, and then the power electronic device branch is turned on again; the control board records and saves the arc detection component detection signal in the three periods of the power electronic device branch being turned on, turned off and turned on again; if the arc detection signal does not change in a short period of time, it can be determined that the signal transmitted by the arc component is a misjudgment; in the case of determining that it is a misjudgment, the power electronic device branch is kept turned on, the mechanical switch or contactor is closed, and the power electronic device branch is disconnected after the mechanical switch or contactor is closed; in the case of determining that it is an arc, the power electronic device branch is disconnected.

[0030] The DC circuit breaker in the embodiment of the present invention can disconnect arc faults more quickly and accurately by adding an arc detection function; by setting the conduction time of the power electronic device branch, the breaking time of the DC circuit breaker is further accelerated, providing safer protection for the system. At the same time, using a contactor instead of a traditional fast mechanical switch can reduce costs and further improve the reliability and engineering practicality of the DC system.

[0031] In the embodiment of the present invention, the power board provides the required different levels of voltage for the components and sensors of the entire DC circuit breaker. The drive signal transmitted from the control board to the drive module adopts optical fiber communication; the opening and closing signal transmitted from the control board to the mechanical switch or contactor adopts electrical signal; the status information of the mechanical switch or contactor is fed back to the control board using electrical signal; the external communication interface of the control board includes RS485, optical fiber, dry contact, Ethernet communication, etc.

[0032] The DC circuit breaker with arc detection function in the embodiment of the present invention can judge and disconnect arc faults more quickly and accurately by adding the arc detection function; by adding the arc detection function in the DC system and adopting the reverse-series crimping power electronic switching device, it can protect DC faults more quickly, accurately and safely, and the volume is smaller than the existing solid-state DC circuit breaker; by setting the branch conduction time of the power electronic device, the opening and closing time of the DC circuit breaker is further accelerated, providing safer protection for the system; at the same time, the use of contactors instead of traditional fast mechanical switches can reduce costs, thereby further improving the reliability and engineering practicality of the DC system.

[0033] Based on the same concept, an embodiment of the present invention further provides a control method for a DC circuit breaker with an arc detection function, which is applied to the aforementioned DC circuit breaker with an arc detection function. Figure 4As shown, the control method of the DC circuit breaker with arc detection function includes:

[0034] Step S11: the control panel receives a tripping command or a first detection signal of arcing transmitted by an arc detection component.

[0035] Before step S11, a variable delay time t1 is determined. The variable delay time is defined as the interval from the moment t when the mechanical switch or contactor is just disconnected to the moment when the power electronic device branch is turned off. The moment t when the mechanical switch or contactor is just disconnected can be obtained through the auxiliary contact.

[0036] In the embodiment of the present invention, the arc detection component transmits a first detection signal indicating that an arc is detected to the control board, and also outputs a second detection signal indicating that an arc is detected to the overall system control circuit of the DC circuit breaker. In step S11, the control board receives a disconnection instruction from the overall system control circuit, the solid-state circuit breaker detects a short circuit condition in real time, or the arc detection component detects the first arc detection signal.

[0037] Step S12: The control board power electronic device branch is turned on, the mechanical switch or contactor is turned off, and the variable delay time t1 is calculated at the same time.

[0038] Specifically, the mechanical switch or contactor is controlled to be turned off, and at the same time, the switch tube in the power electronic device branch is turned on, and the current is transferred to the power electronic device branch.

[0039] Step S13: Calculate the variable delay time t1 according to the through-current.

[0040] Optionally, the current before the mechanical switch or contactor is disconnected is obtained; the current is multiplied by a preset coefficient to obtain a variable delay time t1. Since the current flow in the circuit has different requirements for the shutoff capability, t1 can be multiplied by a preset coefficient k and the current value before disconnection to obtain t1=k*I. The preset coefficient k can be set as needed and is not specifically limited here.

[0041] Step S14: The auxiliary contact of the mechanical switch or contactor is used to detect the opening moment of the mechanical switch or contactor. After a variable delay time t1, the control board turns off the power electronic device branch.

[0042] The auxiliary contact of the mechanical switch or contactor detects the moment t of the mechanical switch or contactor just opening. After the variable delay time t1 at the moment t of opening, the control board shuts off the power electronic device branch. At this time, energy is stored in the energy storage element in the power electronic device branch.

[0043] Step S15: When the energy storage element in the power electronic device branch reaches the action voltage of the energy absorption device, the energy absorption device is turned on, and the energy is consumed by the energy absorption device to complete the disconnection of the DC circuit breaker.

[0044] When the energy storage element in the power electronic device branch reaches the action voltage of the energy absorption device, the energy absorption device is turned on, and the energy in the system is absorbed by the energy absorption device, thereby completing the disconnection of the DC circuit breaker.

[0045] The existing control method requires that the electronic branch can only be disconnected after the mechanical switch or contactor is completely disconnected. In fact, the mechanical switch or contactor does not need to be completely disconnected to meet the insulation conditions of the circuit. Therefore, an embodiment of the present invention proposes a variable delay hybrid DC circuit breaker electronic branch disconnection time control method. In this method, the disconnection time of the electronic branch is a variable delay time t1 after the mechanical switch or contactor just disconnects; the mechanical branch just disconnects The moment can be obtained through the auxiliary contact, and after obtaining the moment t, the electronic branch can be turned off after a variable delay time t1. Because the current size in the circuit has different requirements for the shutoff capability, t1 can be multiplied by a coefficient k and the current value before disconnection to obtain T1=k*I. In this case, the larger the current, the longer the variable delay time T1, and the more reliable the shutdown.

[0046] The embodiment of the present invention can also verify and control the arcing state of the system. Figure 5 As shown, the control board receives the first detection signal of arc detection transmitted by the arc detection component; when the arc state verification function is enabled, the power electronic device branch is turned on, the mechanical switch or contactor is disconnected, and after the mechanical switch or contactor is disconnected, the power electronic device branch is disconnected and kept disconnected for a period of time, and then the power electronic device branch is turned on again; the control board records and saves the detection signal of the arc detection component during the three periods of the power electronic device branch being turned on, turned off and turned on again; if the arc detection signal does not change in a short period of time, it can be determined that the signal transmitted by the arc component is a misjudgment; in the case of determining that it is a misjudgment, the power electronic device branch is kept turned on, the mechanical switch or contactor is closed, and after the mechanical switch or contactor is closed, the power electronic device branch is disconnected; in the case of determining that it is an arc, the power electronic device branch is disconnected.

[0047] The method of the above embodiment is applied to the corresponding DC circuit breaker with arc detection function in the above embodiment, and has the beneficial effects of the corresponding DC circuit breaker with arc detection function, which will not be described in detail here.

[0048] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present application is limited to these examples. Based on the concept of the present application, the technical features in the above embodiments or different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present application as described above, which are not provided in detail for the sake of simplicity.

[0049] This application is intended to cover all such substitutions, modifications and variations that fall within the broad scope of the embodiments of the present invention. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the scope of protection of this application.

Claims

1. A DC circuit breaker with arc detection function, characterized in that: The DC circuit breaker includes: a solid-state circuit breaker and an arc detection component, and the solid-state circuit breaker at least includes: a power electronic device branch, a mechanical switch or contactor, an energy absorption device, a power supply board and a control board. The mechanical switch or contactor is connected in series to the main branch of the DC circuit breaker, the power electronic device branch is connected in parallel to the mechanical switch or contactor, the energy absorption device is connected to the power electronic device branch, the control board is connected to the power electronic device branch and the mechanical switch or contactor; the power supply board is connected to the power electronic device branch, the mechanical switch or contactor, and the arc detection component.

2. The DC circuit breaker according to claim 1, characterized in that: The arc detection component and the solid-state circuit breaker are independently arranged, and the arc detection component is connected to the control board in the solid-state circuit breaker by wired or wireless communication.

3. The DC circuit breaker according to claim 1, characterized in that: The arc detection component adopts a photomultiplier tube module or an arc feature extraction module.

4. The DC circuit breaker according to claim 1, characterized in that: The arc detection component is arranged inside or outside the solid-state circuit breaker and can be flexibly installed according to the required installation and detection conditions.

5. The DC circuit breaker according to claim 4, characterized in that: When the arc detection component is arranged outside, power is provided to the arc detection component by a power board or outside.

6. The DC circuit breaker according to claim 1, characterized in that: The arc detection component includes: a driving module, an arc detection module and a signal processing module connected in sequence; after the arc detection component is powered on, the driving module drives the arc detection module to perform arc detection on the overall system environment where the DC circuit breaker is installed, and when an arc is detected, the signal processing module outputs a first detection signal to the control board to execute the disconnecting operation of the solid-state circuit breaker, and simultaneously outputs a second detection signal to the overall system control circuit of the DC circuit breaker.

7. The DC circuit breaker according to claim 1, characterized in that: The power electronic device branch is provided with a power electronic switch, and the energy absorption device is a metal oxide varistor or a transient suppression diode module.

8. A control method for a DC circuit breaker with an arc detection function, characterized in that: The method comprises: The control panel receives a tripping command or a first detection signal of arcing transmitted by an arc detection component; The control board controls the power electronic device branch to be turned on and the mechanical switch or contactor to be turned off; Calculate the variable delay time t1 according to the through-current; The auxiliary contact of the mechanical switch or contactor detects the initial disconnection time t of the mechanical switch or contactor, and after a variable delay time t1, the control board shuts off the power electronic device branch; When the energy storage element in the power electronic device branch reaches the action voltage of the energy absorption device, the energy absorption device is turned on, and the energy is consumed by the energy absorption device to complete the disconnection of the DC circuit breaker.

9. The control method according to claim 8, characterized in that: The method further includes: verifying and controlling the arcing state of the system, including: The control board receives a first detection signal transmitted by the arc detection component indicating that an arc is detected; When the arc state check function is enabled, the power electronic device branch is turned on, and the mechanical switch or contactor is turned off. After the mechanical switch or contactor is turned off, the power electronic device branch is turned off and remains in the off state for a period of time, and then the power electronic device branch is turned on again; The control board records and stores the detection signals of the arc detection component during the three periods of time when the branch of the power electronic device is turned on, turned off, and turned on again; If the arc detection signal does not change in a short period of time, it can be determined that the signal transmitted by the arc component is a false positive; In the case of a misjudgment, keep the power electronic device branch conducting, close the mechanical switch or contactor, and after the mechanical switch or contactor is closed, disconnect the power electronic device branch; When an arc is detected, the power electronic device branch is disconnected.

10. The control method according to claim 8, characterized in that: The step of calculating the variable delay time t1 according to the through-current comprises: Get the current before the mechanical switch or contactor opens; The variable delay time t1 is obtained by multiplying the current by a preset coefficient.

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