Power distribution network short circuit protection circuit and operation method thereof

Abstract

The invention discloses a power distribution network short-circuit protection circuit and an operation method thereof, and relates to the technical field of power distribution network control. According to the method, an under-voltage comparison unit, an over-current comparison unit, a contactor driving unit, a logic control unit and a CPU main control unit are included. The method is used for isolating the short-circuit fault of the bus bar in the complex power distribution network, has a reclosing function, and improves the reliability of power supply of the power distribution network.

Description

Technical Field

[0001] The present invention belongs to the technical field of power distribution network control, and in particular relates to a power distribution network short-circuit protection circuit and an operation method thereof. Background Art

[0002] The functions of aircraft power distribution systems are becoming increasingly complex, and the requirements for the protection function of the distribution device circuits are also increasing. The power distribution system has many lines and the load importance levels vary greatly. After a short-circuit fault, the line current rises rapidly. If the fault is not isolated in time, it will endanger the safety of the equipment and even cause the entire system to collapse. In other words, a single point fault will endanger the entire network. In order to reduce the scope of the fault, a short-circuit protection circuit is used to quickly cut off the power supply circuit and limit the fault to the fault area. In addition, the purpose of introducing the reclosing switch is to put the distribution system back into operation after the instantaneous fault is eliminated, correct the malfunction of the sampling circuit, the instantaneous short circuit of the airborne equipment, etc., and ensure that the distribution system returns to normal operation in the shortest time.

[0003] Therefore, a short-circuit protection circuit with reclosing function designed for complex power distribution systems is very necessary. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a distribution network short-circuit protection circuit and an operating method thereof, which are intended to be used for isolating bus short-circuit faults in complex distribution networks and have a reclosing function to improve the reliability of power supply in the distribution network.

[0005] According to one aspect of an embodiment of the present invention, there is provided a power distribution network short circuit protection circuit, comprising: a low voltage comparison unit, an overcurrent comparison unit, a contactor drive unit, a logic control unit and a CPU main control unit; The input end of the low-voltage comparison unit is used to input the voltage signal of the power distribution network, and the output end is connected to the logic control unit. The low-voltage comparison unit also includes a voltage acquisition and conditioning circuit, a first comparison circuit and a first isolation circuit. The voltage acquisition and conditioning circuit also includes a resistor R1, a resistor R2 and an operational amplifier U1, wherein the front end of the resistor R1 serves as the input end of the low-voltage comparison unit; the end of the resistor R1 is connected in parallel with the end of the resistor R2, and then connected to the in-phase input end of the operational amplifier U1, and the front end of the resistor R2 is grounded; the first comparison circuit also includes a comparator module U2 and a first reference voltage, wherein the first reference voltage is connected to the in-phase input end of the comparator module U2, and the output end of the operational amplifier U1 is connected to the inverting input end of the comparator module U2 as the output end of the voltage acquisition and conditioning circuit; the input end of the first isolation circuit, i.e., the isolation module M1, is connected to the output end of the comparator module U2, and the output end of the isolation module M1 serves as the output end of the low-voltage comparison unit, outputs an undervoltage protection signal, and is connected to the logic control unit; The input end of the overcurrent comparison unit is used to input the current signal of the power distribution network, and the output end is connected to the logic control unit. The overcurrent comparison unit also includes a current acquisition and conditioning circuit, a second comparison circuit and a second isolation circuit, wherein the current acquisition and conditioning circuit also includes a differential signal acquisition module U3 and an operational amplifier U4, the input end of the differential signal acquisition module U3 serves as the input end of the overcurrent comparison unit, and the in-phase input end of the operational amplifier U4 is connected to the output end of the differential signal acquisition module U3, so as to realize the voltage following function; the second comparison circuit also includes a comparator module U5 and a second reference voltage, the second reference voltage is connected to the in-phase input end of the comparator module U5, and the output end of the operational amplifier U4 is connected to the inverting input end of the comparator module U5 as the output end of the current acquisition and conditioning circuit; the input end of the second isolation circuit, i.e., the isolation module M2, is connected to the output end of the comparator module U5, and the output end of the isolation module M2 serves as the output end of the overcurrent comparison unit, outputs an overcurrent protection signal, and is connected to the logic control unit; The logic control unit is interactively connected to the CPU main control unit, its input end is connected to the low voltage comparison unit and the overcurrent comparison unit, and its output end is connected to the contactor drive unit, for receiving the overcurrent protection signal and the undervoltage protection signal, and sending the control instruction to the contactor drive unit according to the instruction of the CPU main control unit; The CPU main control unit is interactively connected with the logic control unit, and is used to collect the control state of the logic control unit and issue instructions according to the control state; The contactor drive unit is connected to the logic control unit and is used to drive the power distribution network to be turned on and off according to the control instructions.

[0006] Optionally, the power distribution network includes 2 power sources, 5 bus bars and 7 contactors, the first power source is connected to bus PP1 via contactor K1, bus PP1 is connected to bus PP3 via contactor K3, and bus PP3 is connected to bus PP5 via contactor K5; the second power source is connected to bus PP2 via contactor K2, bus PP2 is connected to bus PP4 via contactor K4, and bus PP4 is connected to bus PP5 via contactor K6; bus PP3 is connected to bus PP4 via contactor K7.

[0007] Optionally, shunts I_1 to I_5 are correspondingly arranged between contactors K1 to K5 and busbars PP1 to PP5, shunt I_6 is arranged between contactor K6 and busbar PP5, and shunt I_7 is arranged between contactor K7 and busbar PP4.

[0008] Optionally, the voltage signal of the power distribution network is a bus voltage, and the current signal of the power distribution network is a current flowing through the shunts I_1 to I_7.

[0009] Optionally, the resistance of the shunt I_1 to the shunt I_7 is 0.2 mΩ.

[0010] Optionally, the logic control unit is a CPLD device.

[0011] According to another aspect of an embodiment of the present invention, there is also provided an operation method of a power distribution network short circuit protection circuit, based on any of the above circuits, comprising: When the voltage signal conditioned by the low voltage comparison unit is greater than the first reference voltage, the comparator module U2 outputs a low level; when the voltage signal conditioned by the low voltage comparison unit is less than the first reference voltage, the comparator module U2 outputs a high level; When the voltage signal conditioned by the overcurrent comparison unit is greater than the second reference voltage, the comparator module U5 outputs a high level; when the voltage signal conditioned by the overcurrent comparison unit is less than the second reference voltage, the comparator module U5 outputs a low level; The logic control unit receives the overcurrent protection signal and the undervoltage protection signal, and sends a control instruction to the contactor drive unit according to the preset logic; the CPU main control unit collects the control state of the logic control unit and sends instructions according to the control state; the logic control unit sends a control instruction to the contactor drive unit according to the instruction of the CPU main control unit, and the contactor drive unit drives the power distribution network on and off according to the control instruction.

[0012] Optionally, when the power distribution network is short-circuited, the logic control unit sends a control instruction to the contactor drive unit to disconnect the power distribution network. After the CPU main control unit detects the disconnection state, it starts timing and sends a connection signal after a preset time to connect the power distribution network.

[0013] Optionally, after the power distribution network is connected, if the short circuit of the power distribution network has been cleared, the power distribution network operates normally.

[0014] Optionally, after the power distribution network is connected, if the short circuit of the power distribution network still exists, the timing is turned off.

[0015] The present invention can realize fast short circuit protection of a specific power distribution network and has a reclosing function. When the short circuit fault in the power distribution network is a short-term fault, after the fault is eliminated, the power distribution network has normal power supply capacity, and the method increases the safe operation time of the power distribution system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic diagram of the structure principle of a power distribution network and a short-circuit protection circuit according to an embodiment of the present invention; Figure 2 is a structural principle diagram of an overcurrent ratio unit and a low voltage comparison unit according to an embodiment of the present invention; Figure 3 is a hardware logic control principle diagram of a bus bar PP1 short circuit fault according to an embodiment of the present invention; Figure 4 4 is a flow chart of reclosing control for a busbar PP1 short-circuit fault according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] According to one aspect of an embodiment of the present invention, a power distribution network short circuit protection circuit is provided, such as Figure 1-Figure 2 As shown, it includes: a low voltage comparison unit, an overcurrent comparison unit, a contactor drive unit, a logic control unit and a CPU main control unit; The input end of the low-voltage comparison unit is used to input the voltage signal of the power distribution network, and the output end is connected to the logic control unit. The low-voltage comparison unit also includes a voltage acquisition and conditioning circuit, a first comparison circuit and a first isolation circuit. The voltage acquisition and conditioning circuit also includes a resistor R1, a resistor R2 and an operational amplifier U1, wherein the front end of the resistor R1 serves as the input end of the low-voltage comparison unit; the end of the resistor R1 is connected in parallel with the end of the resistor R2, and then connected to the in-phase input end of the operational amplifier U1, and the front end of the resistor R2 is grounded; the first comparison circuit also includes a comparator module U2 and a first reference voltage, wherein the first reference voltage is connected to the in-phase input end of the comparator module U2. The output end of the operational amplifier U1 is connected as the output end of the voltage acquisition and conditioning circuit and is connected to the inverting input end of the comparator module U2; the input end of the first isolation circuit, i.e., the isolation module M1, is connected to the output end of the comparator module U2, and the output end of the isolation module M1 is used as the output end of the low-voltage comparison unit to output an undervoltage protection signal and is connected to the logic control unit; the function of the resistor R1 and the resistor R2 is to divide the input voltage signal, and the divided voltage signal is connected to the in-phase input end of the operational amplifier U1, and is followed by the operational amplifier U1 to increase the output impedance of the signal; the isolation module M1 realizes the isolation of the analog signal and the digital signal of the voltage.

[0019] The input end of the overcurrent comparison unit is used to input the current signal of the power distribution network, and the output end is connected to the logic control unit. The overcurrent comparison unit also includes a current acquisition and conditioning circuit, a second comparison circuit and a second isolation circuit, wherein the current acquisition and conditioning circuit also includes a differential signal acquisition module U3 and an operational amplifier U4, the input end of the differential signal acquisition module U3 serves as the input end of the overcurrent comparison unit, and the in-phase input end of the operational amplifier U4 is connected to the output end of the differential signal acquisition module U3, so as to realize the voltage following function; the second comparison circuit also includes a comparator module U5 and a second reference voltage, the second reference voltage is connected to the in-phase input end of the comparator module U5, and the output end of the operational amplifier U4 is connected to the inverting input end of the comparator module U5 as the output end of the current acquisition and conditioning circuit; the input end of the second isolation circuit, i.e., the isolation module M2, is connected to the output end of the comparator module U5, and the output end of the isolation module M2 serves as the output end of the overcurrent comparison unit, outputs an overcurrent protection signal, and is connected to the logic control unit; the isolation module M2 has the same function as the isolation module M1, and both can use an optocoupler isolation component.

[0020] The logic control unit is interactively connected to the CPU main control unit, its input end is connected to the low-voltage comparison unit and the over-current comparison unit, and its output end is connected to the contactor drive unit, for receiving over-current protection signals and under-voltage protection signals, and sending control instructions to the contactor drive unit according to the instructions of the CPU main control unit.

[0021] The CPU main control unit is interactively connected with the logic control unit and is used to collect the control state of the logic control unit and issue instructions according to the control state.

[0022] The contactor drive unit is connected to the logic control unit and is used to drive the power distribution network to be turned on and off according to the control instructions.

[0023] Furthermore, the power distribution network includes 2 power sources, 5 bus bars and 7 contactors. The first power source is connected to bus bar PP1 via contactor K1, bus bar PP1 is connected to bus bar PP3 via contactor K3, and bus bar PP3 is connected to bus bar PP5 via contactor K5. The second power source is connected to bus bar PP2 via contactor K2, bus bar PP2 is connected to bus bar PP4 via contactor K4, and bus bar PP4 is connected to bus bar PP5 via contactor K6. Bus bar PP3 is connected to bus bar PP4 via contactor K7. When any bus bar is short-circuited, the bus bar voltage is pulled down to less than 5V, and the current flowing through its power supply side is greater than 1000A.

[0024] Furthermore, shunts I_1 to I_5 are correspondingly arranged between contactors K1 to K5 and busbars PP1 to PP5, shunt I_6 is arranged between contactor K6 and busbar PP5, and shunt I_7 is arranged between contactor K7 and busbar PP4.

[0025] Furthermore, the voltage signal of the power distribution network is the busbar voltage, and the current signal of the power distribution network is the current flowing through the shunt I_1 to the shunt I_7. The input end of the differential signal acquisition module U3 is connected to both ends of the shunt to collect the voltage value at both ends of the shunt to realize current calculation.

[0026] Furthermore, the resistance of the shunt I_1 to the shunt I_7 is 0.2 mΩ. Usually, materials with high current resistance, small impedance and small temperature drift are selected.

[0027] Furthermore, the logic control unit is a CPLD device, and the specific model may be EPM7128AETC100-5N.

[0028] According to another aspect of an embodiment of the present invention, there is also provided an operation method of a power distribution network short circuit protection circuit, based on any of the above circuits, comprising: When the voltage signal conditioned by the low voltage comparison unit is greater than the first reference voltage, the comparator module U2 outputs a low level; when the voltage signal conditioned by the low voltage comparison unit is less than the first reference voltage, the comparator module U2 outputs a high level; When the voltage signal conditioned by the overcurrent comparison unit is greater than the second reference voltage, the comparator module U5 outputs a high level; when the voltage signal conditioned by the overcurrent comparison unit is less than the second reference voltage, the comparator module U5 outputs a low level; The logic control unit receives the overcurrent protection signal and the undervoltage protection signal, and sends a control instruction to the contactor drive unit according to the preset logic; the CPU main control unit collects the control state of the logic control unit and sends instructions according to the control state; the logic control unit sends a control instruction to the contactor drive unit according to the instruction of the CPU main control unit, and the contactor drive unit drives the power distribution network on and off according to the control instruction.

[0029] According to the above power distribution network, the preset logic can be that when bus PP1 is short-circuited, the current I1 flowing through contactor K1 reaches 1000A and triggers the short-circuit protection limit; the current I3 flowing through contactor K3 does not reach 1000A and does not trigger the short-circuit protection limit, and the current I5 flowing through contactor K5 does not reach 1000A and does not trigger the short-circuit protection limit. That is, when I1 reaches the overcurrent protection signal, I3 does not reach the overcurrent protection signal, I5 does not reach the overcurrent protection signal, and bus PP1 has an undervoltage protection signal, it is determined that bus PP1 is short-circuited. The short-circuit protection logic of bus PP2 is the same. When bus PP3 is short-circuited, bus PP1 voltage is less than 5V, bus PP3 voltage is less than 5V, I1 current is greater than 1000A, I3 current is greater than 1000A, I5 current is less than 1000A; that is, when I1 reaches the overcurrent protection signal, I3 reaches the overcurrent protection signal, I5 does not reach the overcurrent protection signal, and bus PP1 has an undervoltage protection signal, bus PP3 has an undervoltage protection signal, it is determined that bus PP3 is short-circuited. The short-circuit protection logic of bus PP4 is the same. When bus PP5 is short-circuited, bus PP5 voltage is less than 5V, I5 current is greater than 1000A or I6 current is greater than 1000A; that is, when bus I5 reaches the overcurrent protection signal or I6 reaches the overcurrent protection signal, bus PP5 has an undervoltage protection signal, it is determined that bus PP5 is short-circuited. The logic design method can accurately identify the short-circuited busbar, quickly cut off the relevant contactor, and accept the instructions of the CPU main control unit to perform the reclosing operation.

[0030] Furthermore, when the power distribution network is short-circuited, the logic control unit sends a control instruction to the contactor drive unit to disconnect the power distribution network. After the CPU main control unit detects the disconnection state, it starts the timing and sends a connection signal after a preset time to connect the power distribution network.

[0031] Furthermore, after the power distribution network is connected, if the short circuit of the power distribution network has been cleared, the power distribution network operates normally.

[0032] Furthermore, after the power distribution network is connected, if the short circuit of the power distribution network still exists at this time, the timing is turned off.

[0033] Example 1 According to the method of the present invention, Figure 1 As shown, the overcurrent comparison unit collects the current value at the shunt position in the distribution network to determine whether there is overcurrent, and the low-voltage comparison unit collects the bus voltage to determine whether there is undervoltage, and outputs the signal to the logic control unit; the logic control unit determines the undervoltage and overcurrent signals at different positions of the distribution network to realize the identification of short-circuit faults, and quickly outputs the drive signal to the contactor control unit; the contactor drive unit adopts field effect transistors to enhance the driving ability of the signal; the CPU main control unit collects the contactor control state of the logic control unit, and outputs the reclosing instruction to the logic control unit.

[0034] The CPU main control unit is connected to the logic control unit to collect the control status of the logic control unit and issue a reset command. When the bus voltage is short-circuited, the logic control unit can quickly disconnect the corresponding contactor. After the CPU main control unit collects this status, it starts the timer, and sends a reset and contactor connection signal after 2 seconds to connect the corresponding contactor; if the short-circuit point has been cleared at this time, the distribution network will work normally; if the short-circuit point still exists at this time, the short-circuit protection logic will be entered, and the reclosing operation will no longer be performed. Here, the reclosing time interval can be adjusted by configuring the timing time in the CPU main control unit.

[0035] Example 2 like Figure 1 As shown, the power distribution network includes 2 power sources, 5 bus bars and 7 contactors. The first power source is connected to bus bar PP1 via contactor K1, bus bar PP1 is connected to bus bar PP3 via contactor K3, and bus bar PP3 is connected to bus bar PP5 via contactor K5; the second power source is connected to bus bar PP2 via contactor K2, bus bar PP2 is connected to bus bar PP4 via contactor K4, and bus bar PP4 is connected to bus bar PP5 via contactor K6; bus bar PP3 is connected to bus bar PP4 via contactor K7. Shunts I_1 to I_5 are correspondingly arranged between contactors K1 to K5 and bus bars PP1 to PP5, shunt I_6 is arranged between contactor K6 and bus bar PP5, and shunt I_7 is arranged between contactor K7 and bus bar PP4. When any bus bar is short-circuited, the bus bar voltage is pulled down to less than 5V, and the current flowing through its power supply side is greater than 1000A.

[0036] Example 3 Figure 3 1 is a schematic diagram of the hardware logic control principle of the bus bar PP1 short-circuit fault according to an embodiment of the present invention; the diagram briefly describes the hardware control logic of the bus bar PP1 short-circuit protection.

[0037] The logic schematic diagram includes: AND gate L1, OR gate L2, OR gate L3, and latch L4, wherein the output ends of the isolation module M1 and the isolation module M2 are connected to the input end of the AND gate L1, the output end of the AND gate L1 is connected to one input end of the OR gate L2, the output end of the latch L4 is connected to the other input end of the OR gate L2, the output end of the OR gate L2 is connected to the input end D of the latch L4, the CPU control module outputs a signal connected to the reset input end of the latch L4, the output end of the latch L4 is respectively connected to the OR gate L3 and the CPU control module acquisition end, the CPU control module outputs a control signal connected to the input end of the OR gate L3, and the output end of the OR gate L3 is used to drive the contactor to achieve fault isolation protection.

[0038] Example 4 Figure 4 This is a flow chart of busbar PP1 short-circuit fault reclosing control according to an embodiment of the present invention. This figure briefly describes the implementation logic and reclosing function of busbar PP1 short-circuit protection.

[0039] When the bus voltage is less than 5V, the voltage acquisition and conditioning circuit will output an undervoltage protection signal; when the current is greater than 1000A (the voltage across the shunt is greater than 200mV), the current acquisition and conditioning circuit will output an overcurrent protection signal; the logic control unit outputs a control signal to achieve a quick disconnection of the contactor; after the CPU main control unit acquires the drive signal, it starts the timer, and sends a reset signal and a contactor connection signal after 2 seconds to connect the corresponding contactor; if the short-circuit point has been cleared at this time, the distribution network will work normally; if the short-circuit point still exists at this time, the short-circuit protection logic will be entered, and the reclosing operation will no longer be performed. Here, the reclosing time interval can be adjusted by configuring the timing time in the CPU main control unit.

[0040] Example 5 Table 1 is a contactor action logic table, that is, when a short circuit occurs in different bus bars, the corresponding contactor can be cut off according to the logic in Table 1.

[0041]

[0042] When bus PP1 is short-circuited, disconnect contactors K1 and K3. When the reclosing fails, the CPU main control unit sends a command to close contactor K7 to ensure that all buses except bus PP1 can work normally. The same applies to bus PP2. When bus PP3 is short-circuited, disconnect contactors K3, K5, and K7 to ensure that all buses except bus PP3 can work normally. The same applies to bus PP4. When bus PP5 is short-circuited, disconnect contactors K5, K6, and K7 to ensure that all buses except bus PP5 can work normally.

[0043] The above is only a specific embodiment of the present invention, and the present invention is described in detail. The unexplained part is a conventional technology. However, the protection scope of the present invention is not limited to this. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A short-circuit protection circuit for a power distribution network, characterized in that: include: Low voltage comparison unit, over current comparison unit, contactor drive unit, logic control unit and CPU main control unit; The input end of the low-voltage comparison unit is used to input the voltage signal of the power distribution network, and the output end is connected to the logic control unit. The low-voltage comparison unit also includes a voltage acquisition and conditioning circuit, a first comparison circuit and a first isolation circuit. The voltage acquisition and conditioning circuit also includes a resistor R1, a resistor R2 and an operational amplifier U1, wherein the front end of the resistor R1 serves as the input end of the low-voltage comparison unit; the end of the resistor R1 is connected in parallel with the end of the resistor R2, and then connected to the in-phase input end of the operational amplifier U1, and the front end of the resistor R2 is grounded; the first comparison circuit also includes a comparator module U2 and a first reference voltage, wherein the first reference voltage is connected to the in-phase input end of the comparator module U2, and the output end of the operational amplifier U1 is connected to the inverting input end of the comparator module U2 as the output end of the voltage acquisition and conditioning circuit; the input end of the first isolation circuit, i.e., the isolation module M1, is connected to the output end of the comparator module U2, and the output end of the isolation module M1 serves as the output end of the low-voltage comparison unit, outputs an undervoltage protection signal, and is connected to the logic control unit; The input end of the overcurrent comparison unit is used to input the current signal of the power distribution network, and the output end is connected to the logic control unit. The overcurrent comparison unit also includes a current acquisition and conditioning circuit, a second comparison circuit and a second isolation circuit, wherein the current acquisition and conditioning circuit also includes a differential signal acquisition module U3 and an operational amplifier U4, the input end of the differential signal acquisition module U3 serves as the input end of the overcurrent comparison unit, and the in-phase input end of the operational amplifier U4 is connected to the output end of the differential signal acquisition module U3, so as to realize the voltage following function; the second comparison circuit also includes a comparator module U5 and a second reference voltage, the second reference voltage is connected to the in-phase input end of the comparator module U5, and the output end of the operational amplifier U4 is connected to the inverting input end of the comparator module U5 as the output end of the current acquisition and conditioning circuit; the input end of the second isolation circuit, i.e., the isolation module M2, is connected to the output end of the comparator module U5, and the output end of the isolation module M2 serves as the output end of the overcurrent comparison unit, outputs an overcurrent protection signal, and is connected to the logic control unit; The logic control unit is interactively connected to the CPU main control unit, its input end is connected to the low voltage comparison unit and the overcurrent comparison unit, and its output end is connected to the contactor drive unit, for receiving the overcurrent protection signal and the undervoltage protection signal, and sending the control instruction to the contactor drive unit according to the instruction of the CPU main control unit; The CPU main control unit is interactively connected with the logic control unit, and is used to collect the control state of the logic control unit and issue instructions according to the control state; The contactor drive unit is connected to the logic control unit and is used to drive the power distribution network to be turned on and off according to the control instructions.

2. A power distribution network short circuit protection circuit according to claim 1, characterized in that: The power distribution network includes two power sources, five bus bars and seven contactors, the first power source is connected to the bus bar PP1 via the contactor K1, the bus bar PP1 is connected to the bus bar PP3 via the contactor K3, and the bus bar PP3 is connected to the bus bar PP5 via the contactor K5; The second power supply is connected to the bus bar PP2 via the contactor K2, the bus bar PP2 is connected to the bus bar PP4 via the contactor K4, and the bus bar PP4 is connected to the bus bar PP5 via the contactor K6; Bus bar PP3 is connected to bus bar PP4 via contactor K7.

3. A power distribution network short circuit protection circuit according to claim 2, characterized in that: Shunts I_1 to I_5 are correspondingly arranged between contactors K1 to K5 and busbars PP1 to PP5, shunts I_6 are arranged between contactor K6 and busbar PP5, and shunts I_7 are arranged between contactor K7 and busbar PP4.

4. A power distribution network short circuit protection circuit according to claim 3, characterized in that: The voltage signal of the power distribution network is the bus voltage, and the current signal of the power distribution network is the current flowing through the shunt I_1 to the shunt I_7.

5. A power distribution network short circuit protection circuit according to claim 3, characterized in that: The resistance of shunt I_1~shunt I_7 is 0.2mΩ.

6. A power distribution network short circuit protection circuit according to claim 1, characterized in that: The logic control unit is a CPLD device.

7. An operating method of a power distribution network short-circuit protection circuit, based on any one of the power distribution network short-circuit protection circuits according to claims 1-6, characterized in that: include: When the voltage signal conditioned by the low voltage comparison unit is greater than the first reference voltage, the comparator module U2 outputs a low level; when the voltage signal conditioned by the low voltage comparison unit is less than the first reference voltage, the comparator module U2 outputs a high level; When the voltage signal conditioned by the overcurrent comparison unit is greater than the second reference voltage, the comparator module U5 outputs a high level; when the voltage signal conditioned by the overcurrent comparison unit is less than the second reference voltage, the comparator module U5 outputs a low level; The logic control unit receives the overcurrent protection signal and the undervoltage protection signal, and sends a control instruction to the contactor drive unit according to the preset logic; the CPU main control unit collects the control state of the logic control unit and sends instructions according to the control state; the logic control unit sends a control instruction to the contactor drive unit according to the instruction of the CPU main control unit, and the contactor drive unit drives the power distribution network on and off according to the control instruction.

8. The method for operating a short-circuit protection circuit for a power distribution network according to claim 7, characterized in that: When the power distribution network is short-circuited, the logic control unit sends a control instruction to the contactor drive unit to disconnect the power distribution network. After the CPU main control unit detects the disconnection state, it starts the timing and sends a connection signal after a preset time to connect the power distribution network.

9. The method for operating a short-circuit protection circuit for a power distribution network according to claim 8, characterized in that: After the power distribution network is connected, if the short circuit of the power distribution network has been cleared, the power distribution network will operate normally.

10. The method for operating a short-circuit protection circuit for a power distribution network according to claim 8, characterized in that: After the power distribution network is connected, if the short circuit of the power distribution network still exists, the timing will be turned off.

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