Multi-port DC circuit breaker suitable for new energy DC collection systems

Abstract

This invention belongs to the field of circuit breaker technology, and is particularly applicable to multi-port DC circuit breakers for new energy DC collection systems. It includes: a housing with multiple inlet interfaces and one outlet interface, and a circuit board installed inside the housing; stationary contacts installed on the inlet interfaces, and movable contacts corresponding to and movable relative to the stationary contacts connected inside the housing; a mechanical switch installed inside the housing to drive the movable contacts; DC branches, one end of each DC branch corresponding to an inlet interface, and the other ends of the DC branches converging to form a DC main circuit, which is connected to the outlet interface; and a solid-state electronic branch for absorbing the arc generated during opening. By incorporating the solid-state electronic branch, this invention can quickly detect the contact status during opening and conduct electricity at the instant of arc generation, transferring the arc current to the solid-state branch, thereby protecting the main contacts from arc erosion and improving the circuit breaker's breaking capacity and reliability against DC fault currents.

Description

Technical Field

[0001] This invention relates to the field of circuit breaker technology, and more particularly to a multi-port DC circuit breaker suitable for new energy DC collection systems. Background Technology

[0002] In new energy power generation systems, especially large-scale photovoltaic power plants, offshore wind farms, and DC microgrids, DC aggregation systems have become a research hotspot and application trend in the power system field due to their advantages such as fewer conversion stages, lower line losses, larger power supply capacity, and more flexible control. In new energy DC aggregation systems, to aggregate the power from multiple distributed power generation units (such as photovoltaic strings and wind turbines) or energy storage units onto a single DC bus, multiple DC feeders (i.e., DC branches) are typically connected in parallel. The reliability of system operation largely depends on the performance of the DC circuit breaker. When a short-circuit fault occurs in a DC branch, the circuit breaker must be able to quickly and reliably interrupt the fault current to ensure the safe and stable operation of the entire DC system and prevent the fault from affecting other normally operating branches.

[0003] Traditional AC circuit breakers cannot be directly applied to DC systems. Currently, circuit breakers used in DC systems mainly face the following technical challenges: Arc extinguishing difficulties: Since direct current has no natural zero-crossing point, a strong electric arc will be generated between the contacts when the circuit breaker breaks. If the arc cannot be extinguished effectively and quickly, the high temperature of the arc will burn the contacts and even cause a fire, resulting in damage to the circuit breaker and seriously threatening equipment safety and system stability.

[0004] High energy dissipation: DC systems typically contain a large number of energy storage components (such as line inductors, filter inductors, capacitors, etc.). When a fault current is interrupted, the enormous magnetic field energy stored in the inductor needs to be dissipated. If this energy cannot be effectively absorbed, a dangerous overvoltage will be generated across the circuit breaker, or even break down the equipment insulation.

[0005] Trade-off between response speed and losses: Existing DC circuit breaker technologies are mainly divided into three categories: mechanical, solid-state, and hybrid. Mechanical circuit breakers have low on-state losses but slow breaking speed and limited arc-extinguishing capability; solid-state circuit breakers use power electronic devices and have extremely fast breaking speeds, but have high on-state losses and high costs; hybrid circuit breakers attempt to combine the advantages of both, but their structure and control are complex, and they also face cost issues.

[0006] Therefore, in response to the special needs of new energy DC collection systems, developing a multi-port DC circuit breaker that can simultaneously handle multiple DC branches, has rapid breaking capability, effectively absorbs arc energy, and is compact and cost-controllable is of great significance for improving the power supply reliability, safety, and economy of new energy DC systems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a multi-port DC circuit breaker suitable for new energy DC aggregation systems, aiming to solve the problems in the background technology.

[0008] To achieve the above-mentioned technical objectives, the specific technical solution of the present invention is as follows: The multi-port DC circuit breaker applicable to new energy DC collection systems proposed in the present invention includes: a housing, on which multiple inlet interfaces and one outlet interface are provided, and a circuit board is installed inside the housing; a stationary contact is installed on the inlet interface, and a movable contact corresponding to and movable relative to the stationary contact is connected inside the housing; a mechanical switch for driving the movable contact to move is installed inside the housing; a DC branch, one end of the DC branch corresponds one-to-one with the inlet interface, the mechanical switch, stationary contact, and movable contact are all connected to the DC branch, and the other end of the DC branch is converged to form a DC main circuit, which is connected to the outlet interface; a solid-state electronic branch for absorbing the arc generated during opening, one end of the solid-state electronic branch is connected to the DC branch, and the other end is connected to the inlet interface.

[0009] Preferably, the solid-state electronic branch includes a current-breaking unit and a driving circuit, wherein the driving circuit is used to detect the open state of the circuit breaker contacts and control the opening and closing of the current-breaking unit.

[0010] Preferably, the interruption unit includes: Solid-state switching transistors are connected in parallel across the DC branch. The freewheeling diode is connected in reverse parallel across the solid-state switching transistor to provide a path for reverse current. The absorption circuit, connected in parallel across the solid-state switch, includes a resistor and a capacitor connected in series. It is used to suppress the voltage generated when the solid-state switch is turned off and to absorb the energy stored in the inductor.

[0011] Preferably, the driving circuit includes: The circuit detection module is used to detect the voltage across the DC branch contacts and determine the closure status of the moving and stationary contacts. The logic control module is used to receive signals sent by the circuit detection module and generate precise turn-on and turn-off timings for solid-state switches. The isolation drive module isolates the low-voltage control circuit from the high-voltage main circuit and provides the drive power required to drive the gate of the solid-state switch. The auxiliary power supply module provides a stable voltage for the drive circuit.

[0012] Preferably, the circuit detection module includes: High-resistance voltage divider resistors are used to convert high voltage to low voltage. The filter circuit is used to filter out high-frequency noise and prevent false triggering. A high-speed voltage comparator used for comparison with a preset voltage.

[0013] Preferably, the logic control module includes a monostable multivibrator and a microcontroller.

[0014] Preferably, the housing is equipped with multiple surge arresters for overvoltage protection, and the surge arresters are connected in parallel on the DC branch.

[0015] Preferably, the housing is equipped with multiple operating handles, and the housing is equipped with a locking mechanism that corresponds to each operating handle. The locking mechanism is connected to a mechanical switch.

[0016] Preferably, the mechanical switch uses an electromagnetic coil, and a lifting rod is connected inside the electromagnetic coil. The two ends of the lifting rod are connected to a moving contact and a locking mechanism, respectively.

[0017] Preferably, the housing is provided with an arc chamber, a metal arc extinguishing plate is installed inside the arc chamber, and an arc channel is provided on the arc chamber.

[0018] The beneficial effects of this invention are as follows: 1. This invention integrates the protection functions of multiple DC branches into a single device by setting up a housing containing multiple incoming interfaces and one outgoing interface. This multi-port structure replaces the traditional approach of configuring a separate circuit breaker for each branch, significantly reducing the installation space of the equipment in the distribution cabinet, simplifying system wiring, and lowering the overall cost of equipment procurement, installation, and maintenance.

[0019] 2. To address the problems of DC current lacking a natural zero-crossing point and difficulty in arc extinguishing, this invention specifically incorporates a solid-state electronic branch. This branch is connected in parallel with the mechanical switch, enabling rapid detection of the contact status during opening and conduction at the instant of arc generation, transferring the arc current to the solid-state branch. Furthermore, the solid-state switch, in conjunction with the absorption circuit, can quickly absorb and dissipate the energy stored in the line inductance, effectively suppressing overvoltage and thus protecting the main contacts from arc erosion. This significantly improves the circuit breaker's breaking capacity and reliability against DC fault currents.

[0020] 3. The drive circuit in the solid-state electronic branch of this invention integrates voltage detection, logic control, and isolation drive functions. It determines the on / off state by real-time monitoring of contact voltage and uses the logic control module to generate precise on / off timing sequences, achieving coordinated operation between mechanical and electronic switches. This intelligent control ensures that in the event of a fault, the circuit breaker can activate the solid-state branch for arc extinguishing with a microsecond-level response speed, achieving rapid protection of the DC system. Attached Figure Description

[0021] Figure 1This is a schematic diagram of the multi-port DC circuit breaker structure proposed in this invention for use in new energy DC collection systems.

[0022] Figure 2 This is an internal schematic diagram of the multi-port DC circuit breaker for new energy DC collection systems proposed in this invention.

[0023] Figure 3 This is a schematic diagram of the arc-extinguishing chamber proposed in this invention.

[0024] Figure 4 This is a schematic diagram of the multi-port DC circuit breaker structure proposed in this invention for use in new energy DC collection systems.

[0025] Figure 5 This is a circuit diagram of the interruption unit proposed in this invention.

[0026] Figure 6 This is a system diagram of the driving circuit proposed in this invention.

[0027] The corresponding names of the attached figures are as follows: 1. Housing; 2. Mechanical switch; 3. Solid-state electronic branch; 4. Inlet interface; 5. Outlet interface; 6. Locking mechanism; 7. Moving contact; 8. Stationary contact; 9. Circuit board; 10. Operating handle; 11. Surge arrester; 12. Arc chamber; 13. DC branch; 14. DC main circuit; 121. Arc channel; 122. Metal arc extinguishing plate; D1. Freewheeling diode; C1. Capacitor; R1. Resistor; IGBT. Solid-state switching transistor. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] Example: This example discloses a multi-port DC circuit breaker suitable for new energy DC aggregation systems, such as... Figures 1-6 As shown, where, as Figure 1As shown, in this embodiment, the multi-port DC circuit breaker is concentrated inside the housing 1. The housing 1 is made of high-insulation-strength engineering plastic or metal material and is equipped with a heat dissipation structure. The housing 1 has multiple inlet interfaces 4 and one outlet interface 5. The interfaces use high-current terminals or plug-ins to facilitate external cable connection. A circuit board 9 is installed inside the housing 1, and the main circuit and control circuit are installed on the circuit board 9. Each inlet interface 4 is equipped with a stationary contact 8. A movable contact 7 that corresponds to and can move relative to the stationary contact 8 is connected inside the housing 1. The housing 1 is equipped with... The mechanical switch 2 is used to drive the moving contact 7 to move up and down, controlling the contact or separation with the stationary contact 8. To enhance the breaking capacity of the mechanical switch 2, an independent arc chamber 12 is provided inside the housing 1. The arc chamber 12 is made of arc-resistant ceramic or plastic, and multiple metal arc-extinguishing plates 122 (grid plates) are installed inside. The arc-extinguishing plates are insulated from each other and arranged in a V-shape. An arc channel 121 is opened on one side of the arc chamber 12, so that the arc generated when the contact is broken enters between the arc-extinguishing plates under the action of electromagnetic force, is divided into short arcs and quickly cooled and extinguished.

[0030] Multiple surge arresters 11 are installed on the housing 1 for overvoltage protection. Each surge arrester 11 is connected in parallel to the corresponding DC branch 13. The surge arrester 11 adopts a zinc oxide varistor or a transient voltage suppressor (TVS) to absorb lightning overvoltage, switching overvoltage and residual energy that may be generated during disconnection. When the branch voltage exceeds the operating voltage of the surge arrester 11, the surge arrester 11 quickly conducts to discharge energy and protect downstream equipment. The surge arrester 11 works in conjunction with the solid-state electronic branch to ensure that the voltage clamping is within a safe range.

[0031] Multiple operating handles 10 are mounted on the housing 1, each corresponding to a DC branch 13. Inside the housing 1 are locking mechanisms 6, each corresponding to one of the operating handles 10. These locking mechanisms 6 are connected to a mechanical switch 2. The mechanical switch 2 employs an electromagnetic operating mechanism, including an electromagnetic coil, an iron core, a push rod, and a return spring. The push rod is connected at both ends to a moving contact 7 and the locking mechanism 6, respectively. The push rod is vertically detachable within the electromagnetic coil. When the electromagnetic coil is energized, the push rod rises, pushing the moving contact 7 to close with the stationary contact 8. When de-energized, the return spring causes the moving contact 7 to separate. The locking mechanism 6 is linked to the operating handles 10. When manually tripping or tripping due to a fault, the locking mechanism 6 releases the mechanical switch 2, ensuring rapid contact disconnection.

[0032] The housing 1 also has multiple DC branches 13. One end of each DC branch 13 corresponds to the input terminal interface 4. The mechanical switch 2, the stationary contact 8, and the moving contact 7 are all connected to the DC branch 13. The other ends of the DC branches 13 are all connected to form a DC bus 14. The DC bus 14 is connected to the output terminal interface 5. This multi-port input and single-port output structure is suitable for new energy DC aggregation scenarios, such as combining the rectified outputs of multiple photovoltaic strings or multiple wind turbines onto a single DC bus. Each DC branch 13 is connected in parallel with a solid-state electronic branch 3. Its core function is to quickly transfer and absorb arc energy when the mechanical switch 2 is disconnected, so as to achieve arc-free disconnection.

[0033] Preferably, the solid-state electronic branch 3 is connected in parallel with the mechanical switch 2, one end of the solid-state electronic branch 3 is connected between the input terminal interface 4 and the stationary contact 8, and the other end is connected between the moving contact 7 and the DC main circuit 14.

[0034] In this embodiment, the solid-state electronic branch 3 includes a current-breaking unit and a driving circuit. The driving circuit is used to detect the disconnection status of the circuit breaker contacts and control the opening and closing of the current-breaking unit.

[0035] like Figure 5 As shown, the interruption unit includes: a solid-state switching transistor (IGBT), whose collector and emitter are respectively connected to the two ends of the DC branch 13, namely the stationary contact 8 side and the load side. The IGBT's turn-on and turn-off are controlled by the drive circuit; a freewheeling diode D1, connected in reverse parallel across the solid-state switching transistor (IGBT) to provide a freewheeling path for the branch inductor current and prevent overvoltage from occurring during turn-off; and an absorption circuit, connected in parallel across the solid-state switching transistor, including a resistor R1 and a capacitor C1 connected in series, used to suppress the voltage generated when the solid-state switching transistor (IGBT) is turned off and to absorb the inductor's stored energy.

[0036] like Figure 6 As shown, the driving circuit includes a circuit detection module, a logic control module, an isolation driving module, and an auxiliary power supply module. The circuit detection module is used to detect the voltage across the contacts of the DC branch 13 to determine the closing status of the moving contact 7 and the stationary contact 8. Specifically, the circuit detection module is used to detect the voltage across the moving contact 7 and the stationary contact 8 in the DC branch 13 to determine whether the moving contact 7 and the stationary contact 8 have started to separate.

[0037] The circuit detection module includes: a high-resistance voltage divider resistor to convert high voltage to low voltage; a filter circuit to filter out high-frequency noise and prevent false triggering; and a high-speed voltage comparator for comparison with a preset voltage. The circuit detection module acquires the voltage across the two contacts of the mechanical switch 2 through the high-resistance voltage divider resistor (e.g., megohm level). After removing high-frequency noise through the filter circuit (RC low-pass filter), the voltage is sent to the high-speed voltage comparator. The comparator compares the measured voltage with a preset threshold (e.g., 20V) and outputs a logic level indicating the contact state. The logic control module uses a microcontroller (MCU) or programmable logic device (CPLD) to receive signals from the circuit detection module and generate precise turn-on and turn-off timings for the solid-state switch. When the contact voltage exceeds the threshold, the contacts begin to separate, generating electrical current. During arcing, a high-level drive signal is immediately output to turn on the solid-state switching transistor (IGBT) and transfer the arc current to the solid-state electronic branch 3. After the branch current decays to zero or after a preset delay, a turn-off signal is output to turn off the solid-state switching transistor (IGBT). The isolation drive module uses an optocoupler or magnetic isolation chip to isolate the low-voltage control signal and drive the gate of the solid-state switching transistor (IGBT), while providing sufficient gate drive current (such as +15V / -5V) to ensure that the solid-state switching transistor (IGBT) turns on and off quickly. The auxiliary power supply module provides a stable voltage for the drive circuit. The auxiliary power supply module draws power from the input terminal interface 4 or an independent auxiliary power supply, and generates a stable low-voltage power supply such as ±15V or +5V through a DC-DC converter to power each module.

[0038] The drive circuit in this embodiment can also integrate current detection functionality, such as monitoring branch current through a Hall sensor or shunt to achieve overcurrent protection. When the detected current exceeds a set value and persists for a certain period of time, the logic control module triggers mechanical switch 2 to open, and simultaneously starts solid-state electronic branch 3. Furthermore, reclosing logic can be set: after a fault is disconnected, if the fault disappears, the system can automatically or manually reclose. For multi-port applications, the solid-state electronic branches of each branch operate independently without interference. When a fault occurs in a branch, only the mechanical switch 2 of that branch opens, while other branches continue to operate normally, achieving selective protection.

[0039] Working principle: When the circuit breaker is normally conducting, the mechanical switch 2 contacts are closed, the solid-state electronic branch 3 is in the off state, and all current flows through the mechanical contact 2, resulting in minimal conduction loss. When a manual or fault-induced tripping command is issued, the mechanical switch 2 begins to operate, the moving contact 7 separates from the stationary contact 8, generating an arc. The voltage detection module immediately senses the rise in voltage across the contacts, i.e., the rise in arc voltage. The drive circuit quickly turns on the solid-state switching transistor IGBT, transferring the arc current to the solid-state electronic branch 3, and the arc is extinguished. Subsequently, the solid-state switching transistor IGBT remains on for a short period of time, such as several hundred microseconds, until the branch current decays to zero before turning off, completing the entire tripping process. During this process, the absorption circuit and the surge arrester 11 jointly absorb the remaining energy and suppress overvoltage.

[0040] Finally, it should be noted that in the description of this invention, the terms "vertical," "upper," "lower," "horizontal," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0041] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multi-port DC circuit breaker suitable for new energy DC collection system, characterized in that, include: Housing (1), housing (1) is provided with multiple inlet interfaces (4) and one outlet interface (5), and a circuit board (9) is installed inside housing (1). A stationary contact (8) is installed on the inlet terminal interface (4), and a movable contact (7) that corresponds to and can move relative to the stationary contact (8) is connected inside the housing (1). A mechanical switch (2) for driving the movable contact (7) to move is installed inside the housing (1). DC branch (13), one end of DC branch (13) corresponds one-to-one with the incoming terminal interface (4), the mechanical switch (2), the stationary contact (8) and the moving contact (7) are all connected to DC branch (13), the other end of DC branch (13) is gathered together to form DC main circuit (14), DC main circuit (14) is connected to outgoing terminal interface (5); Solid-state electronic branch (3) is used to absorb the electric arc generated during circuit breaking. One end of the solid-state electronic branch (3) is connected to the DC branch (13), and the other end is connected to the incoming line interface (4).

2. The multi-port DC circuit breaker suitable for new energy DC collection system according to claim 1, characterized in that, The solid-state electronic branch (3) includes a current-breaking unit and a driving circuit. The driving circuit is used to detect the disconnection status of the circuit breaker contacts and control the opening and closing of the current-breaking unit.

3. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, The interruption unit includes: Solid-state switching transistors are connected in parallel across the DC branch (13); The freewheeling diode is connected in reverse parallel across the solid-state switching transistor to provide a path for reverse current. The absorption circuit, connected in parallel across the solid-state switch, includes a resistor and a capacitor connected in series. It is used to suppress the voltage generated when the solid-state switch is turned off and to absorb the energy stored in the inductor.

4. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, The driving circuit includes: The circuit detection module is used to detect the voltage across the contacts of the DC branch (13) and determine the closing status of the moving contact (7) and the stationary contact (8); The logic control module is used to receive signals sent by the circuit detection module and generate precise turn-on and turn-off timings for solid-state switches. The isolation drive module isolates the low-voltage control circuit from the high-voltage main circuit and provides the drive power required to drive the gate of the solid-state switch. The auxiliary power supply module provides a stable voltage for the drive circuit.

5. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, The circuit detection module includes: High-resistance voltage divider resistors are used to convert high voltage to low voltage. The filter circuit is used to filter out high-frequency noise and prevent false triggering. A high-speed voltage comparator used for comparison with a preset voltage.

6. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, The logic control module includes a monostable multivibrator and a microcontroller.

7. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, Multiple surge arresters (11) are installed on the housing (1) for overvoltage protection. The surge arresters (11) are connected in parallel to the DC branch (13).

8. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, Multiple operating handles (10) are installed on the housing (1). Inside the housing (1) are locking mechanisms (6) that are connected one-to-one with the operating handles (10). The locking mechanisms (6) are connected to the mechanical switch (2).

9. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, The mechanical switch (2) uses an electromagnetic coil, and a lifting rod is connected inside the electromagnetic coil. The two ends of the lifting rod are connected to the moving contact piece (7) and the locking mechanism (6) respectively.

10. The multi-port DC circuit breaker for new energy DC collection systems according to claim 1, characterized in that, The housing (1) is provided with an arc chamber (12), a metal arc extinguishing plate (122) is installed inside the arc chamber (12), and an arc channel (121) is provided on the arc chamber (12).

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