A power distribution network short circuit protection circuit and a method of operation thereof

Abstract

The application 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. The method comprises an under-voltage comparison unit, an over-current comparison unit, a contactor driving unit, a logic control unit and a CPU main control unit. The method is used for isolating bus bar short-circuit faults in a complex power distribution network, has the function of reclosing, and improves the reliability of power supply of the power distribution network.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of power distribution network control, and particularly relates to a power distribution network short-circuit protection circuit and a running method thereof. BACKGROUND

[0002] The function of an aircraft power distribution system is becoming increasingly complex, and the requirement for the protection function of the circuit of the power distribution device is also increasing. The power distribution system has many lines and important load levels, and after a short-circuit fault, the line current rapidly rises. If the fault is not isolated in time, the safety of the equipment is endangered, and even the whole system collapses, that is, a single point fault endangers the whole network. In order to reduce the influence range of the fault, a short-circuit protection circuit is used to quickly cut off the power supply circuit and limit the fault in the fault area. In addition, the purpose of introducing reclosing is to make the power distribution system re-operate after the instantaneous fault is eliminated, correct the situation of the sampling circuit misoperation, the instantaneous short-circuit of the airborne equipment, and the like, and ensure that the power distribution system recovers to the normal operation state in the shortest time.

[0003] Therefore, it is necessary to design a short-circuit protection circuit with a reclosing function for a complex power distribution system. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a power distribution network short-circuit protection circuit and a running method thereof, which are used for isolating the bus bar short-circuit fault in a complex power distribution network, have the function of reclosing, and improve the reliability of power supply of the power distribution network.

[0005] According to one aspect of an embodiment of the present application, a power distribution network short-circuit protection circuit is provided, which comprises a low-voltage comparison unit, an overcurrent comparison unit, a contactor driving unit, a logic control unit and a CPU main control unit.

[0006] The input end of the low-voltage comparison unit is used for inputting a voltage signal of the power distribution network, and the output end is connected with the logic control unit. The low-voltage comparison unit further comprises a voltage acquisition conditioning circuit, a first comparison circuit and a first isolation circuit. The voltage acquisition conditioning circuit further comprises a resistor R1, a resistor R2 and an operational amplifier U1. The front end of the resistor R1 is used 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 with the non-inverting input end of the operational amplifier U1. The front end of the resistor R2 is connected with the ground. The first comparison circuit further comprises a comparator module U2 and a first reference voltage. The first reference voltage is connected with the non-inverting input end of the comparator module U2. The output end of the operational amplifier U1 is connected with the inverting input end of the comparator module U2 as the output end of the voltage acquisition conditioning circuit. The input end of the first isolation circuit, that is, an isolation module M1, is connected with the output end of the comparator module U2. The output end of the isolation module M1 is used as the output end of the low-voltage comparison unit and outputs an under-voltage protection signal. The output end of the low-voltage comparison unit is connected with the logic control unit.

[0007] The overcurrent comparison unit input end is used for inputting the current signal of the power distribution network, and the output end is connected with the logic control unit, and the overcurrent comparison unit further comprises a current collection conditioning circuit, a second comparison circuit and a second isolation circuit, wherein the current collection conditioning circuit further comprises a differential signal collection module U3 and an operational amplifier U4, the input end of the differential signal collection module U3 is used as the overcurrent comparison unit input end, the noninverting input end of the operational amplifier U4 is connected with the output end of the differential signal collection module U3, and the voltage following function is realized; the second comparison circuit further comprises a comparator module U5 and a second reference voltage, the noninverting input end of the comparator module U5 is connected with the second reference voltage, and the output end of the operational amplifier U4 is connected with the inverting input end of the comparator module U5 as the output end of the current collection conditioning circuit; the input end of the second isolation circuit, i.e. the isolation module M2, is connected with the output end of the comparator module U5, and the output end of the isolation module M2 is used as the output end of the overcurrent comparison unit and outputs the overcurrent protection signal and is connected with the logic control unit;

[0008] The logic control unit is interactively connected with the CPU master control unit, the input end is connected with the under-voltage comparison unit and the overcurrent comparison unit, the output end is connected with the contactor driving unit, the overcurrent protection signal and the under-voltage protection signal are received, and the control instruction is sent to the contactor driving unit according to the instruction of the CPU master control unit;

[0009] The CPU master control unit is interactively connected with the logic control unit, the control state of the logic control unit is collected, and the instruction is issued according to the control state;

[0010] The contactor driving unit is connected with the logic control unit, and the on-off of the power distribution network is driven according to the control instruction.

[0011] Optionally, the power distribution network comprises two power sources, five bus bars and seven contactors, the first power source is connected with the bus bar PP1 through the contactor K1, the bus bar PP1 is connected with the bus bar PP3 through the contactor K3, and the bus bar PP3 is connected with the bus bar PP5 through the contactor K5; the second power source is connected with the bus bar PP2 through the contactor K2, the bus bar PP2 is connected with the bus bar PP4 through the contactor K4, and the bus bar PP4 is connected with the bus bar PP5 through the contactor K6; the bus bar PP3 is connected with the bus bar PP4 through the contactor K7.

[0012] Optionally, shunt I_1 to shunt I_5 are arranged between the contactor K1 to the contactor K5 and the bus bar PP1 to the bus bar PP5, shunt I_6 is arranged between the contactor K6 and the bus bar PP5, and shunt I_7 is arranged between the contactor K7 and the bus bar PP4.

[0013] Optionally, the voltage signal of the power distribution network is the bus bar voltage, and the current signal of the power distribution network is the current flowing through the shunt I_1 to the shunt I_7.

[0014] Optionally, the shunt I_1~I_7 has a resistance of 0.2 mΩ.

[0015] Optionally, the logic control unit is a CPLD device.

[0016] According to another aspect of the embodiment of the present application, there is also provided a method for operating a power distribution network short-circuit protection circuit, based on any of the circuits described above, comprising:

[0017] When the low-voltage comparison unit processes the voltage signal to be greater than the first reference voltage, the comparator module U2 outputs a low level, and when the low-voltage comparison unit processes the voltage signal to be less than the first reference voltage, the comparator module U2 outputs a high level.

[0018] When the overcurrent comparison unit processes the voltage signal to be greater than the second reference voltage, the comparator module U5 outputs a high level, and when the overcurrent comparison unit processes the voltage signal to be less than the second reference voltage, the comparator module U5 outputs a low level.

[0019] The logic control unit receives the overcurrent protection signal and the under-voltage protection signal, and sends a control instruction to the contactor driving unit according to a preset logic; the CPU master control unit collects the control state of the logic control unit, and issues an instruction according to the control state; the logic control unit sends a control instruction to the contactor driving unit according to the instruction of the CPU master control unit, and the contactor driving unit drives the on-off of the power distribution network according to the control instruction.

[0020] Optionally, when the power distribution network is short-circuited, the logic control unit sends a control instruction to the contactor driving unit to disconnect the power distribution network, and the CPU master control unit starts timing after collecting the disconnection state, and issues a connection signal after a preset time to connect the power distribution network.

[0021] Optionally, after the power distribution network is connected, if the short circuit of the power distribution network has been cleared at this time, the power distribution network works normally.

[0022] Optionally, after the power distribution network is connected, if the short circuit of the power distribution network still exists at this time, the timing is closed.

[0023] The present application 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-time fault, after the fault is eliminated, the power distribution network has normal power supply capability, and the method increases the safe operation time of the power distribution system. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is a schematic diagram of the structure principle of the power distribution network and the short-circuit protection circuit according to the embodiment of the present application;

[0025] Figure 2It is a structure principle diagram of overcurrent ratio unit and low-voltage comparison unit according to an embodiment of the present application.

[0026] Figure 3 It is a hardware logic control principle diagram of bus bar PP1 short circuit fault according to an embodiment of the present application.

[0027] Figure 4 It is a reclosing control flow chart of bus bar PP1 short circuit fault according to an embodiment of the present application. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] According to an aspect of an embodiment of the present application, a short circuit protection circuit for power distribution network is provided, as shown in Figures 1-2 which comprises a low-voltage comparison unit, an overcurrent comparison unit, a contactor driving unit, a logic control unit and a CPU main control unit.

[0030] The input end of the low-voltage comparison unit is used for inputting a voltage signal of the power distribution network, and the output end is connected with the logic control unit. The low-voltage comparison unit further comprises a voltage acquisition conditioning circuit, a first comparison circuit and a first isolation circuit. The voltage acquisition conditioning circuit further comprises a resistor R1, a resistor R2 and an operational amplifier U1. The front end of the resistor R1 is used 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 with the non-inverting input end of the operational amplifier U1. The front end of the resistor R2 is connected with the ground. The first comparison circuit further comprises a comparator module U2 and a first reference voltage. The first reference voltage is connected with the non-inverting input end of the comparator module U2. The output end of the operational amplifier U1 is connected with the inverting input end of the comparator module U2 as the output end of the voltage acquisition conditioning circuit. The input end of the first isolation circuit, i.e. an isolation module M1, is connected with the output end of the comparator module U2. The output end of the isolation module M1 is used as the output end of the low-voltage comparison unit, and outputs an under-voltage protection signal, which is connected with the logic control unit. The resistor R1 and the resistor R2 are used for dividing the input voltage signal. The divided voltage signal is connected with the non-inverting input end of the operational amplifier U1, which is followed by the operational amplifier U1 to improve the output impedance of the signal. The isolation module M1 realizes the isolation between the analog signal and the digital signal of the voltage.

[0031] The overcurrent comparison unit input end is used for inputting the current signal of the power distribution network, and the output end is connected with the logic control unit, and the overcurrent comparison unit further comprises a current collection conditioning circuit, a second comparison circuit and a second isolation circuit, wherein the current collection conditioning circuit further comprises a differential signal collection module U3 and an operational amplifier U4, the input end of the differential signal collection module U3 is used as the overcurrent comparison unit input end, the noninverting input end of the operational amplifier U4 is connected with the output end of the differential signal collection module U3, and the voltage following function is realized; the second comparison circuit further comprises a comparator module U5 and a second reference voltage, the noninverting input end of the comparator module U5 is connected with the second reference voltage, and the output end of the operational amplifier U4 is connected with the inverting input end of the comparator module U5 as the output end of the current collection conditioning circuit; the input end of the second isolation circuit, i.e. the isolation module M2, is connected with the output end of the comparator module U5, the output end of the isolation module M2 is used as the output end of the overcurrent comparison unit, and the overcurrent protection signal is outputted and connected with the logic control unit; the isolation module M2 has the same effect as the isolation module M1, and both can adopt an optical coupling isolation component.

[0032] The logic control unit is interactively connected with the CPU master control unit, the input end is connected with the under-voltage comparison unit and the overcurrent comparison unit, the output end is connected with the contactor driving unit, the overcurrent protection signal and the under-voltage protection signal are received, and the control instruction is sent to the contactor driving unit according to the instruction of the CPU master control unit.

[0033] The CPU master control unit is interactively connected with the logic control unit, the control state of the logic control unit is collected, and the instruction is issued according to the control state.

[0034] The contactor driving unit is connected with the logic control unit, and is used for driving the on-off of the power distribution network according to the control instruction.

[0035] Further, the power distribution network comprises two power sources, five bus bars and seven contactors, the first power source is connected with the bus bar PP1 through the contactor K1, the bus bar PP1 is connected with the bus bar PP3 through the contactor K3, and the bus bar PP3 is connected with the bus bar PP5 through the contactor K5; the second power source is connected with the bus bar PP2 through the contactor K2, the bus bar PP2 is connected with the bus bar PP4 through the contactor K4, and the bus bar PP4 is connected with the bus bar PP5 through the contactor K6; the bus bar PP3 is connected with the bus bar PP4 through the contactor K7. When short circuit occurs in any bus bar, the bus bar voltage is pulled down to less than 5V, and the current flowing through the power source side is greater than 1000A.

[0036] Further, the shunt I_1 to the shunt I_5 are correspondingly arranged between the contactor K1 to the contactor K5 and the bus bar PP1 to the bus bar PP5, the shunt I_6 is arranged between the contactor K6 and the bus bar PP5, and the shunt I_7 is arranged between the contactor K7 and the bus bar PP4.

[0037] Further, 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 with the two ends of the shunt, and is used for acquiring the voltage value of the two ends of the shunt to realize current calculation.

[0038] Further, the resistance of the shunt I_1 to the shunt I_7 is 0.2 mΩ. Generally, a material with high current resistance, small impedance and small temperature drift is selected.

[0039] Further, the logic control unit is a CPLD device. Specifically, a model EPM7128AETC100-5N can be selected.

[0040] According to another aspect of the embodiment of the present application, there is also provided a running method of a power distribution network short-circuit protection circuit, based on any of the circuits, comprising:

[0041] When the voltage signal after the low-voltage comparison unit is greater than the first reference voltage, the comparator module U2 outputs a low level, and when the voltage signal after the low-voltage comparison unit is less than the first reference voltage, the comparator module U2 outputs a high level.

[0042] When the voltage signal after the overcurrent comparison unit is greater than the second reference voltage, the comparator module U5 outputs a high level, and when the voltage signal after the overcurrent comparison unit is less than the second reference voltage, the comparator module U5 outputs a low level.

[0043] The logic control unit receives the overcurrent protection signal and the under-voltage protection signal, and sends a control instruction to the contactor driving unit according to a preset logic; the CPU master control unit acquires the control state of the logic control unit, and issues an instruction according to the control state; the logic control unit sends a control instruction to the contactor driving unit according to the instruction of the CPU master control unit, and the contactor driving unit drives the on-off of the power distribution network according to the control instruction.

[0044] According to the power distribution network, when the bus bar PP1 has a short circuit, the current I1 flowing through the contactor K1 reaches 1000 A to trigger the short circuit protection limit value; the current I3 flowing through the contactor K3 does not reach 1000 A to not trigger the short circuit protection limit value, and the current I5 flowing through the contactor K5 does not reach 1000 A to not trigger the short circuit protection limit value. 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 the bus bar PP1 has the under-voltage protection signal, it is determined that the bus bar PP1 has a short circuit protection. The short circuit protection logic of the bus bar PP2 is the same. When the bus bar PP3 has a short circuit, the bus bar PP1 voltage is less than 5 V, the bus bar PP3 voltage is less than 5 V, I1 current is greater than 1000 A, I3 current is greater than 1000 A, and I5 current is less than 1000 A; that is, when I1 reaches the overcurrent protection signal, I3 reaches the overcurrent protection signal, I5 does not reach the overcurrent protection signal, and the bus bar PP1 has the under-voltage protection signal and the bus bar PP3 has the under-voltage protection signal, it is determined that the bus bar PP3 has a short circuit. The short circuit protection logic of the bus bar PP4 is the same. When the bus bar PP5 has a short circuit, the bus bar PP5 voltage is less than 5 V, I5 current is greater than 1000 A or I6 current is greater than 1000 A; that is, when the bus bar I5 reaches the overcurrent protection signal or I6 reaches the overcurrent protection signal, and the bus bar PP5 has the under-voltage protection signal, it is determined that the bus bar PP5 has a short circuit. The logic design method can accurately identify the bus bar with a short circuit, quickly cut off the related contactor, and accept the CPU main control unit command to perform the reclosing operation.

[0045] Further, when the power distribution network has a short circuit, the logic control unit sends a control instruction to the contactor driving unit to disconnect the power distribution network, and the CPU main control unit collects the disconnection state, starts the timing, and sends a connection signal after a preset time to connect the power distribution network.

[0046] Further, after the power distribution network is connected, if the short circuit of the power distribution network has been cleared at this time, the power distribution network works normally.

[0047] Further, after the power distribution network is connected, if the short circuit of the power distribution network still exists at this time, the timing is closed.

[0048] Embodiment 1

[0049] According to the method of the application, as Figure 1As shown, the overcurrent comparison unit collects the current value at the position of the shunt in the power distribution network to determine whether overcurrent occurs, and the low-voltage comparison unit collects the busbar voltage to determine whether under-voltage occurs, and outputs the signals to the logic control unit; the logic control unit determines the under-voltage and overcurrent signals at different positions of the power distribution network to identify the short-circuit fault, and quickly outputs a driving signal to the contactor control unit; the contactor driving unit uses a field effect transistor to enhance the driving capability of the signal; the CPU master control unit collects the contactor control state of the logic control unit, and outputs a reclosing instruction to the logic control unit.

[0050] The CPU master control unit is connected with the logic control unit, and is used to collect the control state of the logic control unit, and issue a reset instruction. When the busbar voltage is short-circuited, the logic control unit can quickly disconnect the corresponding contactor. After the CPU master control unit collects the state, a timer is started, and after 2 seconds, a reset and contactor connection signal is sent to connect the corresponding contactor; if the short-circuit point is cleared at this time, the power distribution network works normally; if the short-circuit point still exists at this time, the short-circuit protection logic is entered, and the reclosing operation is no longer performed. Here, the time interval of the reclosing can be adjusted by configuring the timing time in the CPU master control unit.

[0051] Embodiment 2

[0052] As shown in Figure 1 The power distribution network includes two power sources, five busbars and seven contactors. The first power source is connected with the busbar PP1 through the contactor K1, the busbar PP1 is connected with the busbar PP3 through the contactor K3, and the busbar PP3 is connected with the busbar PP5 through the contactor K5. The second power source is connected with the busbar PP2 through the contactor K2, the busbar PP2 is connected with the busbar PP4 through the contactor K4, and the busbar PP4 is connected with the busbar PP5 through the contactor K6. The busbar PP3 is connected with the busbar PP4 through the contactor K7. The shunts I_1 to I_5 are arranged between the contactors K1 to K5 and the busbars PP1 to PP5, respectively, the shunt I_6 is arranged between the contactor K6 and the busbar PP5, and the shunt I_7 is arranged between the contactor K7 and the busbar PP4. When any busbar is short-circuited, the busbar voltage is pulled down to less than 5V, and the current flowing through the power source side is greater than 1000A.

[0053] Embodiment 3

[0054] Figure 3 It is a busbar PP1 short-circuit fault hardware logic control principle diagram according to the embodiment of the application; the diagram briefly describes the hardware control logic of the busbar PP1 short-circuit protection.

[0055] The logic schematic diagram comprises: an AND gate L1, an OR gate L2, an OR gate L3, and a latch L4, wherein the output ends of the isolation module M1 and the isolation module M2 are connected with the input end of the AND gate L1, the output end of the AND gate L1 is connected with one input end of the OR gate L2, the output end Q of the latch L4 is connected with the other input end of the OR gate L2, the output end of the OR gate L2 is connected with the input end D of the latch L4, one output signal of the CPU control module is connected with the reset input end of the latch L4, the output end of the latch L4 is connected with the input end of the OR gate L3 and the acquisition end of the CPU control module, one control signal of the CPU control module is connected with the input end of the OR gate L3, and the output end of the OR gate L3 is used for driving the contactor to realize the isolation protection of the fault.

[0056] Embodiment 4

[0057] Figure 4 It is the short-circuit fault reclosing control flow chart of the bus bar PP1 according to the embodiment of the application. The figure simply describes the realization logic and reclosing function of the bus bar PP1 short-circuit protection.

[0058] When the bus bar voltage is less than 5V, the voltage acquisition conditioning circuit outputs the under-voltage protection signal; when the current is greater than 1000A (the voltage across the shunt is greater than 200mV), the current acquisition conditioning circuit outputs the over-current protection signal; the logic control unit outputs the control signal to realize the quick disconnection operation of the contactor; after the CPU main control unit acquires the driving signal, the timer is started to count, and after 2 seconds, the reset signal and the contactor connection signal are sent to connect the corresponding contactor; if the short-circuit point is removed at this time, the power distribution network works normally; if the short-circuit point still exists at this time, the short-circuit protection logic is entered, and the reclosing operation is not performed. Here, the time interval of the reclosing can be adjusted by configuring the counting time of the CPU main control unit.

[0059] Embodiment 5

[0060] Table 1 is the contactor action logic table, that is, when the short circuit occurs in different bus bars, the corresponding contactor can be cut off according to the logic of Table 1.

[0061]

[0062] When the bus bar PP1 is short-circuited, the contactors K1 and K3 are disconnected, and after the reclosing fails, the contactor K7 is closed by the CPU main control unit, thereby ensuring that the other bus bars except the bus bar PP1 can work normally; after the bus bar PP2 is short-circuited, the same is true. After the bus bar PP3 is short-circuited, the contactors K3, K5 and K7 are cut off, thereby ensuring that the other bus bars except the bus bar PP3 can work normally, and the same is true after the bus bar PP4 is short-circuited. After the bus bar PP5 is short-circuited, the contactors K5, K6 and K7 should be cut off, thereby ensuring that the other bus bars except the bus bar PP5 can work normally.

[0063] The above merely describes specific embodiments of the present application, and the detailed description of the present application is not exhaustive of the conventional technology. However, the protection scope of the present application is not limited to this, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. The protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A short circuit protection circuit for a power distribution network, characterized in that The application relates to a low-voltage comparison unit, an overcurrent comparison unit, a contactor driving unit, a logic control unit and a CPU main control unit. The input end of the low-voltage comparison unit is used for inputting a voltage signal of a power distribution network, and the output end is connected with the logic control unit; the low-voltage comparison unit further comprises a voltage acquisition conditioning circuit, a first comparison circuit and a first isolation circuit; the voltage acquisition conditioning circuit further comprises a resistor R1, a resistor R2 and an operational amplifier U1, wherein the front end of the resistor R1 is used 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 with the non-inverting input end of the operational amplifier U1; the front end of the resistor R2 is connected with the ground; the first comparison circuit further comprises a comparator module U2 and a first reference voltage; the first reference voltage is connected with the non-inverting input end of the comparator module U2; the output end of the operational amplifier U1 is connected with the inverting input end of the comparator module U2 as the output end of the voltage acquisition conditioning circuit; the input end of the first isolation circuit, i.e. an isolation module M1, is connected with the output end of the comparator module U2; the output end of the isolation module M1 is used as the output end of the low-voltage comparison unit and outputs an under-voltage protection signal, which is connected with the logic control unit; The input end of the overcurrent comparison unit is used for inputting a current signal of the power distribution network, and the output end is connected with the logic control unit; the overcurrent comparison unit further comprises a current acquisition conditioning circuit, a second comparison circuit and a second isolation circuit; the current acquisition conditioning circuit further comprises a differential signal acquisition module U3 and an operational amplifier U4; the input end of the differential signal acquisition module U3 is used as the input end of the overcurrent comparison unit; the non-inverting input end of the operational amplifier U4 is connected with the output end of the differential signal acquisition module U3, and is used for realizing a voltage following function; the second comparison circuit further comprises a comparator module U5 and a second reference voltage; the second reference voltage is connected with the inverting input end of the comparator module U5; the output end of the operational amplifier U4 is connected with the non-inverting input end of the comparator module U5 as the output end of the current acquisition conditioning circuit; the input end of the second isolation circuit, i.e. an isolation module M2, is connected with the output end of the comparator module U5; the output end of the isolation module M2 is used as the output end of the overcurrent comparison unit and outputs an overcurrent protection signal, which is connected with the logic control unit; The logic control unit is connected with the CPU main control unit; the input end of the logic control unit is connected with the low-voltage comparison unit and the overcurrent comparison unit; the output end of the logic control unit is connected with the contactor driving unit; the logic control unit is used for receiving the overcurrent protection signal and the under-voltage protection signal, and sending a control instruction to the contactor driving unit according to the instruction of the CPU main control unit; The CPU main control unit is connected with the logic control unit; the CPU main control unit is used for collecting the control state of the logic control unit, and sending an instruction according to the control state; when the power distribution network is short-circuited, the logic control unit sends a control instruction to the contactor driving unit to disconnect the power distribution network; after the CPU main control unit collects the disconnection state, the CPU main control unit starts timing, sends a connection signal after a preset time, and connects the power distribution network; The contactor driving unit is connected with the logic control unit, and is used for driving the on-off of the power distribution network according to the control instruction. ​ 2. The circuit of claim 1, wherein, The power distribution network comprises two power sources, five bus bars and seven contactors, the first power source is connected with the bus bar PP1 through the contactor K1, the bus bar PP1 is connected with the bus bar PP3 through the contactor K3, and the bus bar PP3 is connected with the bus bar PP5 through the contactor K5; The second power source is connected with the bus bar PP2 through the contactor K2, the bus bar PP2 is connected with the bus bar PP4 through the contactor K4, and the bus bar PP4 is connected with the bus bar PP5 through the contactor K6; The bus bar PP3 is connected with the bus bar PP4 through the contactor K7.

3. The circuit of claim 2, wherein, The contactors K1 to K5 and the bus bars PP1 to PP5 are correspondingly provided with shunts I_1 to I_5, the contactor K6 and the bus bar PP5 are provided with the shunt I_6, and the contactor K7 and the bus bar PP4 are provided with the shunt I_7.

4. The circuit of claim 3, wherein, The voltage signal of the power distribution network is the bus bar voltage, and the current signal of the power distribution network is the current flowing through the shunts I_1 to I_7.

5. The circuit of claim 3, wherein, The resistance values of the shunts I_1 to I_7 are 0.2 mΩ.

6. The circuit of claim 1, wherein, The logic control unit is a CPLD device.

7. A method of operation of a short circuit protection circuit for an electrical distribution network, based on a circuit according to any one of claims 1 to 6, characterized in that, Comprise: When the low-voltage comparison unit processes the voltage signal greater than the first reference voltage, the comparator module U2 outputs a low level, and when the low-voltage comparison unit processes the voltage signal less than the first reference voltage, the comparator module U2 outputs a high level; When the overcurrent comparison unit processes the voltage signal greater than the second reference voltage, the comparator module U5 outputs a high level, and when the overcurrent comparison unit processes the voltage signal 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 control instructions to the contactor driving unit according to the preset logic; the CPU master control unit collects the control state of the logic control unit, and issues instructions according to the control state; the logic control unit sends control instructions to the contactor driving unit according to the instructions of the CPU master control unit, and the contactor driving unit drives the on-off of the power distribution network according to the control instructions; When the power distribution network is short-circuited, the logic control unit sends control instructions to the contactor driving unit to disconnect the power distribution network, and the CPU master control unit collects the disconnection state and starts timing, and sends a connection signal after a preset time to connect the power distribution network.

8. The method of claim 7, wherein, After the power distribution network is connected, if the short circuit of the power distribution network has been cleared at this time, the power distribution network works normally.

9. The method of claim 7, wherein, After the power distribution network is connected, if the short circuit of the power distribution network still exists at this time, the timing is closed. After the power distribution network is connected, if the short circuit of the power distribution network has been cleared at this time, the power distribution network works normally. After the power distribution network is connected, if the short circuit of the power distribution network still exists at this time, the timing is closed.

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