Circuit breaker unit and power supply system

Abstract

The invention discloses a circuit breaker unit and a power supply system, and belongs to the technical field of new energy power generation grid connection. The invention provides a circuit breaker unit which comprises a first circuit breaker, the first end of the first circuit breaker is electrically connected with a power grid, and the second end of the first circuit breaker is electrically connected with the power supply end of a load; the shunt release is coupled with the first circuit breaker; the power supply circuit is electrically connected with the shunt release and starts to provide electric energy for the shunt release after target delay time when the voltage of the power grid drops; when the shunt release is in a non-power-on state, the first circuit breaker is in a closed state; when the shunt release is in a power-on state, the first circuit breaker is in a disconnected state. According to the circuit breaker unit, when the voltage of the power grid drops, the shunt release is in the non-power-on state within the target delay time, so that the first circuit breaker is kept in the closed state within the target delay time, and the voltage of the power grid continuously supplies power to the load to realize low voltage ride through.

Description

Technical Field

[0001] The present application belongs to the technical field of renewable energy power generation and grid connection, and in particular, relates to a circuit breaker unit and a power supply system. Background Art

[0002] The backup power system based on new energy sources such as photovoltaic energy storage controls the switching between traditional power grid power supply and photovoltaic and energy storage power supply to achieve a grid-connected mode and an off-grid mode.

[0003] In order to cope with multiple switching between grid connection and off-grid connection, the existing backup power system is equipped with a contactor on the grid side. After the contactor is closed, the backup power system enters the grid connection mode; after the contactor is released, the backup power system switches to the off-grid mode. The grid voltage may drop due to voltage fluctuations and other reasons, and recover after a period of time. This requires the grid-connected equipment to be able to maintain connection with the grid for a certain period of time after the grid voltage drops, waiting for the grid voltage to recover. However, once the contactor coil loses power, the contactor will be released immediately, making it difficult to achieve low voltage ride-through. Summary of the invention

[0004] The present application aims to solve at least one of the technical problems existing in the prior art. To this end, the present application proposes a circuit breaker unit and a power supply system, in which when the grid voltage of the power circuit drops, the first circuit breaker remains in a closed state for a target delay time, and the grid voltage continues to supply power to the load to achieve low voltage ride-through.

[0005] In a first aspect, the present application provides a circuit breaker unit, comprising:

[0006] A first circuit breaker, wherein a first end of the first circuit breaker is used to be electrically connected to the power grid, and a second end of the first circuit breaker is used to be electrically connected to a power supply end of a load;

[0007] A shunt release coupled to the first circuit breaker;

[0008] a power circuit electrically connected to the shunt release and configured to start supplying power to the shunt release after a target delay time when the grid voltage drops;

[0009] When the shunt release is in an unpowered state, the first circuit breaker is in a closed state; when the shunt release is in a powered state, the first circuit breaker is in an open state.

[0010] According to the circuit breaker unit of the present application, when the grid voltage drops, the power supply circuit starts to supply power to the shunt release after a target delay time, and the shunt release is in an unpowered state during the target delay time. Therefore, the first circuit breaker remains in a closed state during the target delay time, and the grid voltage continues to supply power to the load to achieve low voltage ride-through.

[0011] According to one embodiment of the present application, the power supply end of the load is also electrically connected to the inverter, and the power supply circuit includes:

[0012] A switch, wherein a first end of the switch is electrically connected to an inverter or a power grid, and a second end of the switch is electrically connected to a shunt release;

[0013] The control circuit is electrically connected to the driving end of the switch and is configured to control the switch to remain off within a target delay time when the grid voltage drops, and to control the switch to be turned on after the target delay time has passed.

[0014] According to one embodiment of the present application, the power supply circuit further includes:

[0015] A rectifier unit, the AC side of the rectifier unit is used to be electrically connected to the power grid;

[0016] An energy storage unit is electrically connected to the DC side of the rectifying unit, and a first end of the switch is electrically connected to the DC side of the rectifying unit.

[0017] According to an embodiment of the present application, the energy storage unit includes a capacitor, a first end of the capacitor is electrically connected to a first end of the switch, and a second end of the capacitor is electrically connected to the shunt release.

[0018] According to one embodiment of the present application, the rectifier unit includes a full-bridge rectifier circuit, the midpoint of the upper bridge arm of the full-bridge rectifier circuit is electrically connected to the first end of the power grid, the midpoint of the lower bridge arm of the full-bridge rectifier circuit is electrically connected to the second end of the power grid, and the output end of the full-bridge rectifier circuit is electrically connected to the energy storage unit.

[0019] According to one embodiment of the present application, the inverter is a three-phase four-wire inverter, the first end of the switch is electrically connected to any phase of the inverter, and the shunt release is electrically connected to the second end of the switch and the neutral line respectively.

[0020] According to an embodiment of the present application, the circuit breaker unit further includes a voltage protection circuit, which is electrically connected to the first circuit breaker and the grid, respectively, and is configured to control the first circuit breaker to disconnect when the grid voltage is lower than a threshold voltage.

[0021] According to an embodiment of the present application, the low voltage protection circuit includes an undervoltage release, and the undervoltage release is electrically connected to the first circuit breaker and the power grid respectively.

[0022] According to one embodiment of the present application, the target delay time is greater than or equal to 1.5 seconds.

[0023] In a second aspect, the present application provides a power supply system, which includes: an inverter, a second circuit breaker and the aforementioned circuit breaker unit, the first end of the second circuit breaker is electrically connected to the inverter, the second end of the second circuit breaker is electrically connected to the power supply end of the load, and the circuit breaker unit is electrically connected to the power grid and the second end of the second circuit breaker, respectively.

[0024] According to the power supply system of the present application, when the grid voltage drops, the power supply circuit starts to supply power to the shunt release after a target delay time. The shunt release is in an unpowered state during the target delay time. Therefore, the first circuit breaker remains in a closed state during the target delay time, and the grid voltage continues to supply power to the load to achieve low voltage ride-through.

[0025] Additional aspects and advantages of the present application will be given in part in the description below, and in part will become apparent from the description below, or will be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0027] Figure 1 It is a circuit diagram of a backup power system in the related art;

[0028] Figure 2 is a structural block diagram of a circuit breaker unit provided in an embodiment of the present application;

[0029] Figure 3 is one of the circuit diagrams of the circuit breaker unit provided in the embodiment of the present application;

[0030] Figure 4 This is the second circuit diagram of the circuit breaker unit provided in the embodiment of the present application.

[0031] Reference numerals:

[0032] Circuit breaker unit 100, shunt release 110, power circuit 120, rectifier unit 121, energy storage unit 122, voltage protection circuit 130, power grid 200, inverter 300, load 400, contactor K0, first to second circuit breakers K1-K2, switch S, capacitor C. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and cannot be understood as limiting the present application.

[0034] In the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "coupled to" or "connected to" another element or an element / circuit is said to be "coupled to" or "connected to" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. On the contrary, when an element is said to be "directly coupled to" or "directly connected to" another element, it means that there is no intermediate element between the two.

[0035] In the description, the terms "first", "second", etc. are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the numerical descriptors used in this way are interchangeable where appropriate, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", etc. are generally of the same type, and the number of objects is not limited. For example, the first object can be one or more. In addition, "and / or" in the specification and claims represents at least one of the connected objects, and the character " / " generally indicates that the objects associated with each other are in an "or" relationship.

[0036] In addition, descriptions with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0037] The backup power system based on new energy sources such as photovoltaic storage controls the switching between the power supply of the traditional power grid 200 and the power supply of photovoltaic and energy storage to achieve a grid-connected mode connected to the power grid 200 and an off-grid mode disconnected from the power grid 200.

[0038] Reference Figure 1 , Figure 1The circuit of the backup power system in the related art is shown. In the related art, in order to cope with multiple switching of grid connection and off-grid connection, a contactor K0 is usually provided on the grid 200 side of the backup power system. After the contactor K0 is energized, the backup power system enters the grid connection mode; after the contactor K0 is released, the backup power system switches to the off-grid mode. When the contactor K0 is at a relatively low power, the release time of the contactor K0 is very fast, and the function of fast grid connection and off-grid connection can be realized. However, with the continuous increase in power, the backup power system needs to be equipped with a larger contactor K0. The large-sized contactor K0 is limited by the mechanical structure, and its release time will gradually increase, and it can no longer meet the requirements of the backup power system to quickly disconnect from the grid. In addition, the voltage of the grid 200 may drop due to voltage fluctuations and other reasons on the grid 200 side, and recover after a period of time. This requires the grid-connected equipment to be able to maintain connection with the grid 200 for a certain period of time after the voltage of the grid 200 just drops, so as to wait for the voltage of the grid 200 to recover, but once the contactor K0 coil loses power, the contactor K0 will be released immediately, making it difficult to achieve low voltage ride-through.

[0039] Reference Figure 2 , Figure 2 The structure of the circuit breaker unit 100 provided in an embodiment of the present application is shown. An embodiment of the present application proposes a circuit breaker unit 100, which includes: a first circuit breaker K1, a shunt release 110 and a power supply circuit 120. The first end of the first circuit breaker K1 is used to be electrically connected to the power grid 200, and the second end of the first circuit breaker K1 is used to be electrically connected to the power supply end of the load 400; the shunt release 110 is coupled to the first circuit breaker K1; the power supply circuit 120 is electrically connected to the shunt release 110, and is configured to start providing electrical energy to the shunt release 110 after a target delay time when the voltage of the power grid 200 drops; wherein, when the shunt release 110 is in an unpowered state, the first circuit breaker K1 is in a closed state; when the shunt release 110 is in a powered state, the first circuit breaker K1 is in an open state.

[0040] The first end of the first circuit breaker K1 is electrically connected to the grid 200 to receive power supply from the grid 200. The second end of the first circuit breaker K1 is electrically connected to the power supply end of the load 400 to ensure that power can be smoothly and stably transmitted to the load 400 equipment.

[0041] The shunt release 110 is coupled to the first circuit breaker K1, and the shunt release 110 is mainly used to accurately control the opening and closing state of the first circuit breaker K1 according to the received electrical signal instruction. When the shunt release 110 is in an unpowered state, that is, when it does not receive the electric energy from the power circuit 120, the first circuit breaker K1 remains in a closed state, and the power can be transmitted normally. However, once the shunt release 110 receives the electric energy provided by the power circuit 120, that is, when it is in the powered state, the shunt release 110 immediately triggers the action, so that the first circuit breaker K1 quickly switches from the on state to the off state, thereby effectively cutting off the power supply.

[0042] The power circuit 120 is electrically connected to the shunt release 110, and is mainly used to provide electric energy to the shunt release 110. When the voltage of the power grid 200 drops, that is, when the power supply of the power grid 200 is unstable, the power circuit 120 starts to provide electric energy to the shunt release 110 after the target delay time. The target delay time is designed to maintain the shunt release 110 in an unpowered state for a period of time after the voltage of the power grid 200 drops, that is, the circuit breaker remains in the energized state for a period of time after the voltage of the power grid 200 drops, so as to cope with possible instantaneous voltage fluctuations, avoid unnecessary circuit breaker operation, and achieve low voltage ride-through.

[0043] After the target delay time ends, if the voltage of the power grid 200 has not yet returned to stability, the power circuit 120 starts to automatically provide power to the shunt release 110, and the shunt release 110 is triggered to cause the first circuit breaker K1 to quickly switch from the on state to the off state, thereby effectively cutting off the circuit and preventing equipment damage or safety accidents caused by a fault in the power grid 200 or other abnormal conditions.

[0044] It should be noted that the specific value of the target delay time can be selected according to the actual application scenario and is not limited here. For example, the target delay time can be 1.5s or 1.6s.

[0045] In summary, when the backup power system operates normally, the first circuit breaker K1 is in the on state. When the voltage of the power grid 200 drops, within the target delay time, the power circuit 120 does not supply power to the shunt release 110, that is, within the target delay time, the first circuit breaker K1 remains in the on state, and the power grid 200 continues to supply power to the load 400 to achieve low voltage ride-through; after the target delay time, if the voltage of the power grid 200 has not yet returned to stability, the power circuit 120 provides power to the shunt release 110, and the shunt release 110 triggers an action, so that the first circuit breaker K1 quickly switches from the on state to the off state, thereby effectively cutting off the circuit and preventing equipment damage or safety accidents caused by a fault in the power grid 200 or other abnormal conditions.

[0046] According to the circuit breaker unit 100 of the present application, when the voltage of the power grid 200 drops, the power circuit 120 starts to provide power to the shunt release 110 after a target delay time. The shunt release 110 is in an unpowered state during the target delay time. Therefore, the first circuit breaker K1 remains in a closed state during the target delay time, and the voltage of the power grid 200 continues to supply power to the load 400 to achieve low voltage ride-through.

[0047] In some embodiments, the power supply end of the load 400 is also electrically connected to the inverter 300, and the power circuit 120 includes a switch S and a control circuit. The first end of the switch S is used to be electrically connected to the inverter 300 or the power grid 200, and the second end of the switch S is electrically connected to the shunt release 110; the control circuit is electrically connected to the driving end of the switch S, and is configured to control the switch S to remain off within the target delay time when the voltage of the power grid 200 drops, and control the switch S to be turned on after the target delay time.

[0048] The power supply end of the load 400 is electrically connected to the inverter 300, which can improve the stability and reliability of the power supply. The inverter 300 can be used as a backup power supply or power conditioning equipment, and can provide stable power output to the load 400 when the power grid 200 fails or the power supply is unstable.

[0049] The switch S can be electrically connected between the inverter 300 and the shunt release 110. When the voltage of the power grid 200 drops, the control circuit controls the switch S to remain turned off within the target delay time. At this time, the shunt release 110 is in an unpowered state, and the first circuit breaker K1 remains in a closed state. After the target delay time, if the voltage of the power grid 200 has not yet recovered to be stable, the control circuit controls the switch S to be turned on, and the inverter 300 provides electrical energy to the shunt release 110 through the switch S, so that the shunt release 110 is in a powered state, and the first circuit breaker K1 is quickly switched from the on state to the off state, thereby effectively cutting off the power supply.

[0050] The switch S can also be electrically connected between the power grid 200 and the shunt release 110. When the voltage of the power grid 200 drops, the working principle of the circuit breaker unit 100 can refer to the above-mentioned embodiment and will not be described in detail here. After the target delay time, if the voltage of the power grid 200 has not yet recovered to be stable, the control circuit controls the switch S to be turned on, and the electric energy provided by the power grid 200 can be transmitted to the shunt release 110 through the switch S, so that the shunt release 110 is in the power-on state, so that the first circuit breaker K1 is quickly switched from the on state to the off state, thereby effectively cutting off the power supply.

[0051] Reference Figure 3 , Figure 3The circuit of the circuit breaker unit 100 provided in an embodiment of the present application is shown. In some embodiments, the power supply circuit 120 further includes a rectifier unit 121 and an energy storage unit 122. The AC side of the rectifier unit 121 is used to be electrically connected to the power grid 200; the energy storage unit 122 is electrically connected to the DC side of the rectifier unit 121, and the first end of the switch S is electrically connected to the DC side of the rectifier unit 121.

[0052] The AC side of the rectifier unit 121 is electrically connected to the power grid 200 and is mainly used to convert the AC power obtained from the power grid 200 into DC power to provide a stable and reliable DC power supply for subsequent circuits.

[0053] The energy storage unit 122 is electrically connected to the DC side of the rectifier unit 121, and is mainly used to store the AC power outputted from the DC side of the rectifier unit 121. The first end of the switch S is electrically connected to the DC side of the rectifier unit 121. When a fault occurs in the power grid 200, that is, after the target delay time, when the voltage of the power grid 200 has not yet recovered to be stable, the control circuit controls the switch S to be turned on, and the electric energy stored in the energy storage unit 122 can power on the shunt release 110, thereby controlling the first circuit breaker K1 to switch from the on state to the off state.

[0054] In some embodiments, the energy storage unit 122 includes a capacitor C, a first end of the capacitor C is electrically connected to a first end of the switch S, and a second end of the capacitor C is electrically connected to the shunt release 110 .

[0055] The capacitor C is electrically connected between the switch S and the shunt release 110. When the backup power system operates normally, the rectifier unit 121 converts the AC power obtained from the power grid 200 into DC power, and the capacitor C stores part of the DC power. When the voltage of the power grid 200 drops, and after the target delay time, the voltage of the power grid 200 has not yet returned to stability, the control circuit controls the switch S to turn on, and the electric energy stored in the capacitor C can power on the shunt release 110, thereby controlling the first circuit breaker K1 to switch from the on state to the off state.

[0056] In some embodiments, the rectifier unit 121 includes a full-bridge rectifier circuit, the midpoint of the upper bridge arm of the full-bridge rectifier circuit is electrically connected to the first end of the power grid 200, the midpoint of the lower bridge arm of the full-bridge rectifier circuit is electrically connected to the second end of the power grid 200, and the output end of the full-bridge rectifier circuit is electrically connected to the energy storage unit 122.

[0057] The upper arm and lower arm of the full-bridge rectifier circuit are alternately turned on in one cycle, and can use all two half-cycles of the AC signal for rectification, with high rectification efficiency. In addition, the output voltage waveform of the full-bridge rectifier circuit is relatively smooth and the ripple is small, which is conducive to improving the stability of the circuit, reducing noise interference, and making the output voltage closer to the ideal DC.

[0058] Reference Figure 4 , Figure 4 The circuit of the circuit breaker unit 100 provided in the embodiment of the present application is shown. In some embodiments, the inverter 300 is a three-phase four-wire inverter, the first end of the switch S is electrically connected to any phase of the inverter 300, and the shunt release 110 is electrically connected to the second end of the switch S and the neutral line respectively.

[0059] The shunt release 110 can be an AC-driven shunt release 110. The switch S is electrically connected between any phase of the inverter 300 and the shunt release 110. When the voltage of the power grid 200 drops, the control circuit controls the switch S to remain off within the target delay time. At this time, the shunt release 110 is in a non-powered state, and the first circuit breaker K1 remains in a closed state. After the target delay time, if the voltage of the power grid 200 has not yet recovered to be stable, the control circuit controls the switch S to be turned on, and the inverter 300 provides electrical energy to the shunt release 110 through the switch S, so that the shunt release 110 is in a powered state, and the first circuit breaker K1 is quickly switched from the on state to the off state, thereby effectively cutting off the power supply.

[0060] The shunt release 110 directly draws power from the AC side of the inverter 300, which simplifies the circuit structure. Even if the grid 200 loses power, the inverter 300 can still supply power to the separation release, and the shunt release 110 can obtain enough power to switch the first circuit breaker K1 from the on state to the off state.

[0061] In some embodiments, the circuit breaker unit 100 further includes a voltage protection circuit 130 , which is electrically connected to the first circuit breaker K1 and the grid 200 , respectively, and is configured to control the first circuit breaker K1 to disconnect when the voltage of the grid 200 is lower than a threshold voltage.

[0062] The voltage protection circuit 130 is electrically connected between the first circuit breaker K1 and the power grid 200. The voltage protection circuit 130 can detect the voltage of the power grid 200 in real time. When the voltage of the power grid 200 is lower than the threshold voltage, it indicates that a fault occurs on the power grid 200 side. At this time, the voltage protection circuit 130 controls the first circuit breaker K1 to disconnect, so as to prevent a sudden drop in voltage at the load 400 end, a shutdown of the electrical equipment or a safety accident caused by a fault in the power grid 200.

[0063] The specific value of the threshold voltage can be set according to the actual application scenario and is not limited here. For example, the threshold voltage can be 50V or 60V.

[0064] In some embodiments, the low voltage protection circuit 130 includes an undervoltage release, which is electrically connected to the first circuit breaker K1 and the power grid 200 respectively.

[0065] The undervoltage release may include a voltage sensor and a drive circuit. The voltage sensor is mainly used to monitor the voltage of the power grid 200 in real time, and the drive circuit can control the action of the release according to the signal of the voltage sensor.

[0066] The undervoltage release monitors the voltage of the power grid 200 in real time through a voltage sensor. When the voltage of the power grid 200 drops below the threshold voltage, the voltage sensor converts the detected voltage change into an electrical signal and transmits it to the drive circuit. After receiving this signal, the drive circuit will issue an instruction to disconnect the first circuit breaker K1 to prevent equipment damage or safety accidents caused by a fault in the power grid 200 or other abnormal conditions.

[0067] In some embodiments, the target delay time is greater than or equal to 1.5 seconds.

[0068] The duration of the voltage drop of the power grid 200 is usually about 1.5 seconds. By setting the target delay time equal to 1.5 seconds, the first circuit breaker K1 can remain in a closed state during the target delay time during the period of the voltage drop of the power grid 200, and the voltage of the power grid 200 continues to supply power to the load 400 to achieve low voltage ride-through.

[0069] The target delay time is set to be greater than 1.5 seconds to leave a certain margin for the backup power system to achieve low voltage ride-through, to cope with possible instantaneous voltage fluctuations, to avoid unnecessary circuit breaker action, and to achieve low voltage ride-through.

[0070] An embodiment of the present application proposes a power supply system, which includes: an inverter 300, a second circuit breaker K2 and the aforementioned circuit breaker unit 100, wherein the first end of the second circuit breaker K2 is electrically connected to the inverter 300, the second end of the second circuit breaker K2 is electrically connected to the power supply end of the load 400, and the circuit breaker unit 100 is electrically connected to the power grid 200 and the second end of the second circuit breaker K2, respectively.

[0071] When the voltage of the power grid 200 is normal, the first circuit breaker K1 in the circuit breaker unit 100 is closed, the second circuit breaker K2 is turned off, and the power grid 200 provides power to the load 400; when the voltage of the power grid 200 drops, the circuit breaker unit 100 keeps the first circuit breaker K1 closed within the target delay time to achieve low voltage ride-through; if the voltage of the power grid 200 has not recovered after the target delay time, the first circuit breaker K1 in the circuit breaker unit 100 is turned off, the second circuit breaker K2 is turned on, and the load 400 switches from the grid-connected operation state to the off-grid operation state, and the inverter 300 provides power to the load 400.

[0072] The structure and working principle of the circuit breaker unit 100 may refer to the aforementioned embodiments and will not be described in detail here.

[0073] According to the power supply system of the present application, when the voltage of the power grid 200 drops, the power circuit 120 starts to provide power to the shunt release 110 after a target delay time. The shunt release 110 is in an unpowered state during the target delay time. Therefore, the first circuit breaker K1 remains in a closed state during the target delay time, and the voltage of the power grid 200 continues to supply power to the load 400 to achieve low voltage ride-through.

[0074] Although the embodiments of the present application have been shown and described, those skilled in the art will appreciate that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present application, and that the scope of the present application is defined by the claims and their equivalents.

Claims

1. A circuit breaker unit, characterized in that: include: A first circuit breaker, wherein a first end of the first circuit breaker is used to be electrically connected to a power grid, and a second end of the first circuit breaker is used to be electrically connected to a power supply end of a load; a shunt release coupled to the first circuit breaker; a power circuit electrically connected to the shunt release and configured to start supplying power to the shunt release after a target delay time when the grid voltage drops; Wherein, when the shunt release is in an unpowered state, the first circuit breaker is in a closed state; When the shunt release is in a powered-on state, the first circuit breaker is in a disconnected state.

2. The circuit breaker unit according to claim 1, characterized in that The power supply end of the load is also electrically connected to the inverter, and the power supply circuit includes: A switch, wherein a first end of the switch is used to be electrically connected to the inverter or the grid, and a second end of the switch is electrically connected to the shunt release; The control circuit is electrically connected to the driving end of the switch and is configured to control the switch to remain turned off within the target delay time when the grid voltage drops, and to control the switch to be turned on after the target delay time has passed.

3. The circuit breaker unit according to claim 2, characterized in that The power supply circuit also includes: A rectifier unit, wherein the AC side of the rectifier unit is used to be electrically connected to the power grid; An energy storage unit, wherein the energy storage unit is electrically connected to the DC side of the rectifying unit, and the first end of the switch is electrically connected to the DC side of the rectifying unit.

4. The circuit breaker unit according to claim 3, characterized in that The energy storage unit comprises a capacitor, a first end of the capacitor is electrically connected to a first end of the switch, and a second end of the capacitor is electrically connected to the shunt release.

5. The circuit breaker unit according to claim 4, characterized in that The rectifier unit includes a full-bridge rectifier circuit, the midpoint of the upper bridge arm of the full-bridge rectifier circuit is electrically connected to the first end of the power grid, the midpoint of the lower bridge arm of the full-bridge rectifier circuit is electrically connected to the second end of the power grid, and the output end of the full-bridge rectifier circuit is electrically connected to the energy storage unit.

6. The circuit breaker unit according to claim 2, characterized in that The inverter is a three-phase four-wire inverter, the first end of the switch is electrically connected to any phase of the inverter, and the shunt release is electrically connected to the second end of the switch and the neutral line respectively.

7. The circuit breaker unit according to claim 6, characterized in that The circuit breaker unit further includes a voltage protection circuit, which is electrically connected to the first circuit breaker and the grid, respectively, and is configured to control the first circuit breaker to be disconnected when the grid voltage is lower than a threshold voltage.

8. The circuit breaker unit according to claim 7, characterized in that The low voltage protection circuit comprises an undervoltage release, and the undervoltage release is electrically connected to the first circuit breaker and the power grid respectively.

9. The circuit breaker unit according to any one of claims 1 to 8, characterized in that: The target delay time is greater than or equal to 1.5 seconds.

10. A power supply system, characterized in that: include: An inverter, a second circuit breaker and a circuit breaker unit according to any one of claims 1 to 9, wherein the first end of the second circuit breaker is electrically connected to the inverter, the second end of the second circuit breaker is electrically connected to the power supply end of the load, and the circuit breaker unit is electrically connected to the power grid and the second end of the second circuit breaker respectively.

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