A method and apparatus for protecting an airborne high voltage direct current system

Abstract

The application provides a kind of airborne high-voltage direct current system protection method and device, the system includes DC bus, protection controller and the distribution function unit connected between DC bus and each function unit branch, distribution function unit at least includes series connection's explosive fuse, contactor and current sensor;Including the following steps: each function unit branch is defined as power supply branch or load branch, and forward action logic and reverse action logic based on current flow direction are set for power supply branch and load branch respectively;System operation, current amplitude and direction signal flowing through each function unit branch are collected in real time using current sensor, and current amplitude and direction signal are transmitted to protection controller;Protection controller selects corresponding action logic according to the direction signal detected currently, and compares current amplitude with action threshold in selected action logic, when current amplitude exceeds action threshold, explosive fuse or contactor is triggered to execute protection action.

Description

Technical Field

[0001] This invention belongs to the field of airborne high-voltage direct current system short-circuit protection technology, specifically relating to an airborne high-voltage direct current system protection method and device. Background Technology

[0002] With the accelerating pace of research and development in transportation electrification, aircraft are continuously evolving towards more electric and all-electric systems, and their system capacity is constantly increasing. High-voltage direct current (HVDC) systems, due to their ability to connect to various power sources and loads and achieve high-power integration, are gradually becoming a development trend in the aviation field. However, airborne HVDC systems place extremely stringent requirements on equipment weight control, while also demanding high levels of speed and reliability from protection systems.

[0003] In ground-based DC systems, protection devices typically rely on DC circuit breakers or load switch fuse assemblies. While air-operated DC circuit breakers provide protection, their large size and weight make them unsuitable for the lightweight requirements of airborne systems. Load switch fuse assemblies, on the other hand, use fuses as protection devices. Accurate fault current characteristics require a precise system calculation model to obtain accurate data, which serves as the input for fuse selection or specialized design.

[0004] The existing airborne DC system protection schemes have the following main problems: (1) Traditional thermal fuses have a long operating time, which makes it difficult to meet the needs of high voltage DC systems to quickly clear faults; (2) The protection logic is relatively simple, usually based only on the current amplitude, without considering the current direction factor. In scenarios with multiple power sources connected in parallel or bidirectional power flow, it may lead to protection maloperation or failure to operate; (3) The same protection strategy is used for power supply branches and load branches, lacking targeted differentiated protection schemes, making it difficult to achieve optimal protection coordination; (4) There is a lack of effective backup protection measures, and the system faces a greater risk when the main protection fails. Summary of the Invention

[0005] This invention proposes a protection method and device for airborne high-voltage DC systems, which solves the problems of slow protection response speed and poor protection reliability in existing technologies.

[0006] To address the aforementioned technical problems, this invention provides a protection method for an airborne high-voltage direct current system. The system includes at least a DC bus, a protection controller, and power distribution functional units connected between the DC bus and each functional unit branch. Each power distribution functional unit includes at least a series-connected explosion-proof fuse and a current sensor. The method comprises the following steps:

[0007] Step S1: Define each functional unit branch connected to the DC bus as a power supply branch or a load branch, and set forward operation logic and reverse operation logic based on the current flow direction for the power supply branch and the load branch respectively.

[0008] Step S2: During system operation, the current sensor is used to collect the current amplitude and direction signals flowing through each functional unit branch in real time, and the current amplitude and direction signals are transmitted to the protection controller.

[0009] Step S3: The protection controller selects the corresponding action logic based on the currently detected direction signal and compares the current amplitude with the action threshold in the selected action logic. When the current amplitude exceeds the action threshold, the explosion fuse or contactor is triggered to perform the protection action.

[0010] Preferably, in step S1, the direction in which the power supply branch supplies power to the DC bus is defined as positive, and the direction in which the power supply branch draws power from the DC bus is defined as negative.

[0011] The direction in which the load branch draws power from the DC bus is defined as positive, and the direction in which the load branch supplies power to the DC bus is defined as negative.

[0012] Preferably, the protection controller in step S3 selects the corresponding action logic based on the currently detected direction signal, including the following steps:

[0013] For the power supply branch: when the direction signal of the current is detected to be positive and the current amplitude exceeds the short circuit threshold, short-delay protection is executed to control the contactor to trip; if the fault duration exceeds the first preset delay, the explosive fuse is triggered.

[0014] When the direction signal of the current is detected to be reversed and the current amplitude exceeds the short-circuit threshold, instantaneous protection is performed, and the explosive fuse is immediately triggered.

[0015] For the load branch: when the direction signal of the current is detected to be positive and the current amplitude exceeds the short-circuit threshold, instantaneous protection is performed, and the explosive fuse is immediately triggered;

[0016] When the direction signal of the current is detected to be reversed and the current amplitude exceeds the short-circuit threshold, short-delay protection is executed to control the contactor to trip; if the fault duration exceeds the second preset delay, the explosive fuse is triggered.

[0017] Preferably, the duration settings of both the first preset delay and the second preset delay are greater than the action time of the instantaneous protection.

[0018] Preferably, the explosive fuse integrates a thermal triggering module, which serves as backup protection for the protection controller to trigger the explosive fuse.

[0019] Preferably, in step S2, before the system is run, a power-on insulation detection step is also included: before the system is powered on, the insulation status of the DC bus and each of the functional unit branches is detected by a voltage sensor. When an insulation fault is detected, the system is prohibited from being powered on.

[0020] The present invention also provides an airborne high-voltage DC system protection device, which is applicable to the above-mentioned airborne high-voltage DC system protection method. The device includes at least: a DC bus, a power distribution functional unit, and a protection controller.

[0021] The DC bus is used to connect the branches of each functional unit.

[0022] The power distribution functional unit is connected between the DC bus and each functional unit branch. The power distribution functional unit includes at least a series-connected explosion fuse and a current sensor. The current sensor is used to collect the current amplitude and current direction signals flowing through each functional unit branch in real time.

[0023] The protection controller is connected to the current sensor and the explosion fuse, and is used to receive the current amplitude and the current direction signals, and determine whether to trigger the explosion fuse to perform a protection action according to the preset action logic.

[0024] The functional unit branch is defined as a power supply branch or a load branch, and the protection controller is configured with forward action logic and reverse action logic based on the current flow direction for the power supply branch and the load branch, respectively.

[0025] Preferably, the explosive fuse integrates a thermal triggering module, which is used as backup protection to trigger the explosive fuse to operate when the protection controller fails.

[0026] Preferably, the power distribution functional unit further includes a contactor connected in series with the explosive fuse, wherein the contactor is one of a solid contactor, an air contactor, or a gas-filled contactor.

[0027] Preferably, the power distribution functional unit further includes a voltage sensor, which is used to detect the insulation status of the DC bus and each branch of the functional unit before the system is powered on.

[0028] The beneficial effects of the present invention include at least the following:

[0029] 1. Using explosive fuses as protective actuators, compared with traditional thermal fuses, it has the advantages of fast action speed and strong breaking capacity. It can cut off fault current in a hundred microseconds and effectively protect system equipment.

[0030] 2. Introducing current direction detection, combined with current amplitude, enables directional protection, which can accurately determine the fault location and fault type, improving the selectivity and reliability of the protection.

[0031] 3. Differentiated protection logic is set for power supply branches and load branches to achieve differentiated handling of forward and reverse faults. Through the cooperation of instantaneous protection and short-delay protection, bus faults can be quickly cleared, and time can be provided for branch protection to coordinate, thus achieving selective coordination of protection. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the method flow according to an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of the device structure according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the protection action when a short circuit occurs in the power supply branch in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of the protection action when a short circuit occurs in the load branch in an embodiment of the present invention;

[0036] Figure 5 This is a schematic diagram of the protection action when a short circuit occurs on the busbar in an embodiment of the present invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0038] Example 1

[0039] This invention provides an airborne high-voltage DC system protection device, which includes a DC bus, a power distribution unit, and a protection controller.

[0040] The DC bus serves as the main power transmission line of the system, connecting the various functional unit branches. In this embodiment, the system employs a kilovolt-level high-voltage DC power supply, and the DC bus includes a positive bus and a negative bus. Functional unit branches connected to the DC bus are defined as power supply branches or load branches based on their functional characteristics. Power supply branches connect to power equipment such as generator rectifiers and energy storage batteries, responsible for supplying power to the DC bus; load branches connect to load equipment such as electric actuators and avionics equipment, drawing power from the DC bus to operate.

[0041] The power distribution functional unit is connected between the DC bus and each functional unit branch, with one power distribution functional unit corresponding to each functional unit branch. The power distribution functional unit includes at least an explosion fuse and a current sensor connected in series.

[0042] A pyrofuse is a fast-acting switch based on pyrotechnic technology, containing an electric igniter and a pyrotechnic agent. Upon receiving a trigger signal from the protection controller, the igniter ignites the pyrotechnic agent, generating high-temperature, high-pressure gas that drives the cutting mechanism to cut off the circuit within microseconds. Compared to traditional thermistor fuses, pyrofuse fuses offer advantages such as fast action, high breaking capacity, and reliable electrical isolation after activation. Furthermore, a thermal trigger module is integrated within the pyrofuse fuse. This module is a triggering device based on a thermistor material. When the current flowing through the pyrofuse fuse continuously exceeds the rated value, the conductor heats up, causing the thermal trigger module's temperature to rise. When the activation threshold is reached, the pyrofuse fuse is automatically triggered. The thermal trigger module serves as backup protection for the protection controller, ensuring system safety even if the main protection fails.

[0043] Current sensors are used to acquire the amplitude and direction signals of the current flowing through each functional unit branch in real time. Closed-loop Hall effect current sensors can be used, which operate by utilizing the Hall effect to detect the magnetic field strength around the conductor, thereby indirectly measuring the current flowing through the conductor. The closed-loop structure improves measurement accuracy and response speed through negative feedback compensation, making it suitable for protection applications in high-voltage DC systems.

[0044] In a preferred embodiment, the power distribution unit further includes a contactor connected in series with the explosive fuse. The contactor can be a solid-state contactor, an air contactor, or a gas-insulated contactor. The contactor is used to achieve normal on / off control of the branch circuit and can disconnect the branch circuit during system startup, shutdown, or maintenance. Solid-state contactors use power semiconductor devices to switch current, offering advantages such as no contacts, long lifespan, and fast operation; air contactors use electromagnetically driven mechanical contacts, suitable for high-current applications; gas-insulated contactors are filled with inert gas around the contacts, improving breaking capacity and service life. The explosive fuse works in conjunction with the contactor; the contactor is responsible for on / off control under normal operating conditions, while the explosive fuse is responsible for rapid disconnection during faults, their functions complementing each other.

[0045] In another preferred embodiment, the power distribution unit further includes a voltage sensor. The voltage sensor is used to detect the insulation status of the DC bus and each functional unit branch before the system is powered on. The voltage sensor can employ a voltage divider resistor measurement or an isolated measurement method, enabling accurate measurement of the voltage to ground and the line-to-line voltage of the high-voltage DC system. By injecting a detection signal and measuring the response voltage before the system is powered on, the insulation status of the system is determined to be normal.

[0046] The protection controller connects to the current sensor and the explosion fuse to receive current amplitude and direction signals, and determines whether to trigger the explosion fuse to perform a protection action based on preset operating logic. The protection controller can be implemented using a digital signal processor (DSP) or a field-programmable gate array (FPGA), providing high-speed computation and real-time response capabilities. Internally, the protection controller stores protection parameters for each branch, including branch type, short-circuit threshold, and delay time. Based on the branch type and the real-time detected current direction signal, the protection controller selects the appropriate protection logic for judgment.

[0047] Example 2

[0048] like Figure 1 As shown, this embodiment of the invention also provides a protection method for an airborne high-voltage direct current system, implemented based on the above-mentioned protection device. The method includes the following steps:

[0049] Step S1: Define each functional unit branch connected to the DC bus as a power supply branch or a load branch, and set forward and reverse operation logic based on the current flow direction for the power supply branch and the load branch respectively.

[0050] Specifically, the current direction is defined as follows: For power supply branches, the direction of power supply from the DC bus to the power source is defined as positive, and the direction of power supply from the DC bus to the power source is defined as negative; for load branches, the direction of power supply from the DC bus to the load is defined as positive, and the direction of power supply from the DC bus to the load is defined as negative. This definition method conforms to the current flow characteristics of various branches during normal operation, facilitating fault type identification.

[0051] Step S2: When the system is running, the current sensor is used to collect the current amplitude and direction signals flowing through each functional unit branch in real time, and the current amplitude and direction signals are transmitted to the protection controller.

[0052] During system operation, current sensors are used to collect the current amplitude and direction signals flowing through each functional unit branch in real time, and transmit these signals to the protection controller. The current amplitude signal reflects the magnitude of the current and is used to determine whether an overcurrent or short-circuit fault has occurred; the direction signal reflects the direction of current flow and is used to determine the fault type and location.

[0053] Preferably, before system operation, a power-on insulation detection step is also included: before powering on the system, the insulation status of the DC bus and each functional unit branch is detected using a voltage sensor. If an insulation fault is detected, the system is prohibited from powering on. This step can detect potential insulation problems before the system is powered on, avoiding operation with faults.

[0054] Step S3: The protection controller selects the corresponding action logic based on the currently detected direction signal and compares the current amplitude with the action threshold in the selected action logic. When the current amplitude exceeds the action threshold, the explosion fuse is triggered to perform the protection action.

[0055] The protection controller selects the corresponding action logic based on the currently detected direction signal and compares the current amplitude with the action threshold in the selected action logic. When the current amplitude exceeds the action threshold, the explosion fuse is triggered to perform the protection action.

[0056] The protection logic for the power supply branch is as follows:

[0057] When the current direction signal is detected to be positive and the current amplitude exceeds the short-circuit threshold, a short-circuit fault is determined to have occurred downstream of the power supply branch. At this time, short-delay protection is executed, controlling the contactor to trip. The short-circuit threshold should cover the normal operating current of the system, generally taken as 1.2-1.5 times or more of the rated operating current, calculated using a digital simulation model of the airborne high-voltage DC system for typical fault points. If the fault duration exceeds the first preset delay T1, the explosive fuse is triggered to clear the fault. The purpose of setting the short delay is to allow time for coordination with downstream protection, achieving selective coordination of protection. If the downstream protection clears the fault within the delay time, the protection of the power supply branch will automatically reset and does not need to operate. The delay time T1 should cover the full operating time of the downstream protection and reserve a certain margin. The operating time of the explosive fuse is generally no more than 1ms and has low dispersion. Considering the influence of the airborne system line impedance on the full breaking time of the explosive fuse, the preset delay time of the power supply branch should generally be greater than 1ms.

[0058] When a reverse current signal is detected and the current amplitude exceeds the short-circuit threshold, it is determined that a fault has occurred inside the power supply or in the power supply branch itself, causing the reverse current. In this case, instantaneous protection is activated, immediately triggering the explosion fuse to clear the fault. Since the reverse current indicates that the fault occurs in this branch or inside the power supply, there is no protection coordination issue; therefore, instantaneous action is adopted.

[0059] The protection logic for the load branch is as follows:

[0060] When a positive current direction signal is detected and the current amplitude exceeds the short-circuit threshold, a short-circuit fault is determined to have occurred downstream of the load branch or inside the load. In this case, instantaneous protection is activated, immediately triggering the explosion fuse to clear the fault. Since there are generally no lower-level protections on the load side to coordinate with, instantaneous action is used to clear the fault as quickly as possible.

[0061] When a reverse current signal is detected and the current amplitude exceeds the short-circuit threshold, it is determined that a fault in the DC bus or other branches has caused the reverse current. In this case, short-delay protection is executed, controlling the contactor to trip. If the fault duration exceeds the second preset delay T2, the explosion fuse is triggered. The purpose of setting the short delay is to wait for the protection of the faulty branch to take priority action, achieving selective coordination of protection. The delay time T2 is designed to cover the instantaneous full breaking time of the explosion fuse in the branch fault and to trigger as quickly as possible. The setting principle can refer to the short-delay setting strategy for forward current in power supply branches.

[0062] The duration settings for both the first preset delay T1 and the second preset delay T2 are greater than the action time of the instantaneous protection. In practical applications, the action time of instantaneous protection is typically 0.1~1ms, while the delay time for short-delay protection can be set to 2~5ms, with the specific value determined based on the system's protection coordination requirements. By appropriately setting the delay time, timing coordination between the main protection and backup protection can be achieved, ensuring that faults can be selectively cleared.

[0063] While the protection controller triggers the explosive fuse, the thermal triggering module integrated within the explosive fuse continues to operate as backup protection. If the electrical trigger fails due to a protection controller malfunction, communication interruption, or other reasons, the thermal triggering module will automatically trigger the explosive fuse after sufficient heat is generated by continuous current overload, ensuring that the fault can ultimately be cleared. The thermal triggering module's operating time is typically on the order of seconds, much longer than the millisecond-level operating time of the electrical trigger, therefore it will not affect the selective coordination of normal protection.

[0064] Example 3

[0065] The protection method of this invention will be further explained below in conjunction with specific application scenarios.

[0066] like Figure 2 As shown in a specific application embodiment, a certain type of aircraft adopts a kilovolt-level high-voltage DC power distribution system. The system includes two generator channels, one energy storage battery channel as power supply branches, and eight load channels as load branches. Each channel is equipped with a power distribution functional unit, which includes an explosion fuse, a current sensor, a contactor, and a voltage sensor.

[0067] The protection controller employs a dual-redundancy design, with two controller channels operating independently and serving as backups for each other. Each controller channel receives current signals from all power distribution functional units and independently performs protection calculations and judgments. When either controller channel determines that action is required, it issues a trigger signal to ensure the reliability of the protection operation.

[0068] Scenario 1: A short circuit fault occurs inside the power supply branch.

[0069] like Figure 3 As shown, taking a short-circuit fault at the rectifier outlet of the left generator unit as an example, the protection process is explained in detail. When a short circuit occurs at the rectifier outlet of the left generator unit, each branch provides short-circuit current to the short-circuit point F1.

[0070] At this time, the current flowing through the explosion fuse of the left power generation unit branch is negative. If the detected current exceeds the threshold, instantaneous protection is activated, and the fuse is immediately detonated to cut off the current.

[0071] The current flowing through the energy storage unit and the right power generation unit branch explosion fuse is positive. According to the set positive short-delay action logic, it will not operate for a short delay; or it will operate as backup protection after the instantaneous failure of the left power generation unit branch explosion fuse.

[0072] The current flowing through the electric drive unit and the load branch explosion fuse is negative. According to the set negative short-delay action logic, it will not operate for a short delay; or it will operate as backup protection after the instantaneous failure of the explosion fuse in the left generator unit branch.

[0073] In summary, when the rectifier outlet of the left generator unit fails, only the explosion fuse of the left generator unit branch trips, instantly cutting off the faulty branch, while the other branches maintain their operating status, thus achieving selective protection of the system under this condition.

[0074] Scenario 2: A short circuit fault occurs inside the load branch.

[0075] like Figure 4 As shown, taking a short-circuit fault at the inverter inlet of the left electric drive unit as an example, the protection process is explained in detail. When a short circuit occurs at the inverter inlet of the left electric drive unit, each branch provides short-circuit current to the short-circuit point F2.

[0076] At this time, the current flowing through the explosion fuse of the left electric drive unit branch is in the positive direction. If the detected current exceeds the threshold, instantaneous protection is activated, and the fuse is immediately detonated to cut off the current.

[0077] The current flowing through the explosion fuses of the power generation unit and energy storage unit branches is positive. According to the set positive short-delay action logic, it will not operate for a short delay; or it will operate as backup protection after the instantaneous failure of the explosion fuse of the left electric drive unit branch.

[0078] The current flowing through the right electric drive unit and the load branch explosion fuse is negative. According to the set negative short-delay action logic, it will not operate for a short delay; or it will operate as backup protection after the instantaneous failure of the left electric drive unit branch explosion fuse.

[0079] In summary, when the inverter input of the left electric drive unit fails, only the explosion fuse of the left electric drive unit branch will trip, cutting off the faulty branch, while the other branches can maintain their operating status, thus achieving selective protection of the system under this condition.

[0080] Scenario 3: A short circuit fault occurs on the busbar.

[0081] like Figure 5 As shown, taking a short-circuit fault on the left busbar as an example, the protection process is explained in detail. When a short circuit occurs on the left busbar, each branch provides short-circuit current to the short-circuit point F3.

[0082] At this time, the protection controller uses a differential algorithm to quickly identify the faulty bus and drives the explosive fuse at the bus tie to detonate and disconnect, thereby disconnecting the faulty bus from the system.

[0083] The current flowing through the explosion fuses in the power generation unit and energy storage unit branches is positive. According to the set operating logic, it will not operate for a short time; or it will operate for a delay after the explosion fuse at the bus tie fails instantaneously as backup protection.

[0084] The current flowing through the electric drive unit and the load branch explosion fuse is negative. According to the set operating logic, it will not operate for a short time; or it will operate for a delay after the explosion fuse at the bus tie fails instantaneously as backup protection.

[0085] In summary, when a fault occurs in a certain busbar section, the busbar switch instantaneously isolates the faulty area, ensuring continuous operation in the non-faulty areas. Even if the exploding fuse at the bus tie fails instantaneously, a thermal trigger serves as backup, achieving selective protection for the system under this condition.

[0086] This invention reduces the weight of the airborne power distribution unit by using a combination of explosive fuses and contactors as core components. This enables directional and programmable protection, better distinguishing different fault locations and achieving selective protection. This prevents fault escalation and ensures continuous normal operation in non-faulty areas, preventing system power loss. After the system switches operating topology, the controller threshold parameters are adjusted to achieve adaptive protection.

[0087] It can sense the operating status of airborne high-voltage DC systems during operation, supporting optimized system operation control. When a fault occurs in the airborne DC system, it can act quickly to achieve selective protection. The method is simple and reliable, the equipment is lightweight, economical and practical, easy to promote, and contributes to the safe and large-scale development of the electric transportation industry.

[0088] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described; only preferred embodiments of the present invention are illustrated. The descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. As long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0089] It should be noted that those skilled in the art can make various modifications and improvements without departing from the inventive concept, and these all fall within the scope of protection of this invention. Therefore, the scope of protection of this invention should be determined by the appended claims.

Claims

1. A protection method for an airborne high-voltage direct current system, the system comprising at least a DC bus, a protection controller, and power distribution functional units connected between the DC bus and each functional unit branch, wherein the power distribution functional unit comprises at least an explosion fuse, a contactor, and a current sensor connected in series, characterized in that, The method includes the following steps: Step S1: Define each functional unit branch connected to the DC bus as a power supply branch or a load branch, and set forward operation logic and reverse operation logic based on the current flow direction for the power supply branch and the load branch respectively. The direction in which the power supply branch supplies power to the DC bus is defined as positive, and the direction in which the power supply branch draws power from the DC bus is defined as negative; the direction in which the load branch draws power from the DC bus is defined as positive, and the direction in which the load branch supplies power to the DC bus is defined as negative. Step S2: During system operation, the current sensor is used to collect the current amplitude and direction signals flowing through each functional unit branch in real time, and the current amplitude and direction signals are transmitted to the protection controller. Step S3: The protection controller selects the corresponding action logic based on the currently detected direction signal, and compares the current amplitude with the action threshold in the selected action logic. When the current amplitude exceeds the action threshold, the explosion fuse or contactor is triggered to perform the protection action. The protection controller selects the corresponding action logic based on the currently detected direction signal, including the following steps: For the power supply branch: when the direction signal of the current is detected to be positive and the current amplitude exceeds the short circuit threshold, short-delay protection is executed to control the contactor to trip; if the fault duration exceeds the first preset delay, the explosive fuse is triggered. When the direction signal of the current is detected to be reversed and the current amplitude exceeds the short-circuit threshold, instantaneous protection is performed, and the explosive fuse is immediately triggered. For the load branch: when the direction signal of the current is detected to be positive and the current amplitude exceeds the short-circuit threshold, instantaneous protection is performed, and the explosive fuse is immediately triggered; When the direction signal of the current is detected to be reversed and the current amplitude exceeds the short-circuit threshold, short-delay protection is executed to control the contactor to trip; if the fault duration exceeds the second preset delay, the explosive fuse is triggered.

2. The airborne high-voltage DC system protection method according to claim 1, characterized in that: The duration settings of both the first preset delay and the second preset delay are greater than the action time of the instantaneous protection.

3. The airborne high-voltage DC system protection method according to claim 1, characterized in that: The explosive fuse has an integrated thermal triggering module, which serves as backup protection for the protection controller to trigger the explosive fuse.

4. The airborne high-voltage DC system protection method according to claim 1, characterized in that: In step S2, before the system is put into operation, a power-on insulation detection step is also included: before the system is powered on, the insulation status of the DC bus and each functional unit branch is detected by a voltage sensor. When an insulation fault is detected, the system is prohibited from being powered on.

5. An airborne high-voltage direct current system protection device, applicable to the airborne high-voltage direct current system protection method as described in any one of claims 1-4, characterized in that, The device includes at least: a DC bus, a power distribution unit, and a protection controller; The DC bus is used to connect the branches of each functional unit. The power distribution functional unit is connected between the DC bus and each functional unit branch. The power distribution functional unit includes at least a series-connected explosion fuse and a current sensor. The current sensor is used to collect the current amplitude and current direction signals flowing through each functional unit branch in real time. The protection controller is connected to the current sensor and the explosion fuse, and is used to receive the current amplitude and the current direction signals, and determine whether to trigger the explosion fuse to perform a protection action according to the preset action logic. The functional unit branch is defined as a power supply branch or a load branch, and the protection controller is configured with forward action logic and reverse action logic based on the current flow direction for the power supply branch and the load branch, respectively.

6. The airborne high-voltage DC system protection device according to claim 5, characterized in that: The explosive fuse has an integrated thermal triggering module, which is used as backup protection to trigger the explosive fuse to operate when the protection controller fails.

7. The airborne high-voltage DC system protection device according to claim 5, characterized in that: The power distribution unit also includes a contactor connected in series with the explosive fuse, wherein the contactor is one of a solid contactor, an air contactor, or a gas-filled contactor.

8. The airborne high-voltage DC system protection device according to claim 5, characterized in that: The power distribution functional unit also includes a voltage sensor, which is used to detect the insulation status of the DC bus and each branch of the functional unit before the system is powered on.

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