A fault detection system and method for output fuses of substation battery banks

Abstract

This invention discloses a fault detection system for output fuses of a substation battery bank, comprising at least a maintenance and recovery circuit, a control circuit, and a signal circuit. The maintenance and recovery circuit detects the status of the positive and negative fuses, and, under the control of the control circuit, reconnects the two ends of the blown positive or negative fuse after it has blown. The control circuit controls the maintenance and recovery circuit according to the status of the positive and negative fuses. The signal circuit acquires and transmits the status information of the positive and negative fuses. This invention also discloses a corresponding method. Implementing this invention allows for real-time detection of whether the battery bank output fuses are functioning correctly, and automatically restores the connection between the battery bank and the DC bus when an abnormality is detected, providing convenience, timeliness, and improved safety.

Description

Technical Field

[0001] This invention relates to the field of substation battery testing technology, and in particular to a substation battery bank output fuse fault detection system and method. Background Technology

[0002] The substation's DC power supply system is responsible for providing a stable and reliable DC power supply to all equipment in the substation. Secondary equipment such as relay protection devices, remote control devices, and communication devices primarily rely on the DC power supply system for operation. Some switch and disconnector mechanism boxes, control power supplies, etc., also rely on the DC power supply system. The battery bank, serving as a backup power source for the DC system, is connected to the DC bus via a set of positive and negative fuses, providing power to the DC system in the event of an AC power failure.

[0003] In some applications, such as after the battery pack is replaced, if the battery output fuse is not activated, or if the battery output fuse blows, the entire substation's protection and control circuits will lose DC power after the AC power supply to the station, which may cause a substation voltage failure.

[0004] However, in the current technology, the battery output fuses are not given much attention in the operation and maintenance of DC equipment. The monitoring methods are limited, and it is not possible to detect in time the aging of the battery output fuses or poor internal contact. When there is a large current surge, it will cause the battery output fuses to open, which may lead to the further expansion of the accident.

[0005] Therefore, how to conveniently and accurately monitor whether the battery output fuse is functioning properly is an urgent issue that needs to be addressed. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method and system for detecting faults in the output fuses of a substation battery bank. This method can detect whether the output fuses of the battery bank are normal in real time and automatically restore the connection between the battery bank and the DC bus when an abnormality is detected. This is convenient, timely, and improves safety.

[0007] The technical solution adopted in this invention is as follows: A substation battery bank output fuse fault detection system is provided, which includes at least a maintenance and recovery circuit, a control circuit, and a signal circuit, wherein:

[0008] The maintenance and recovery circuit is connected to both ends of the positive and negative fuses of the battery pack. It is used to detect the status of the positive and negative fuses and, under the control of the control circuit, connect both ends of the blown positive or negative fuse after the positive or negative fuse blows.

[0009] The control circuit is used to control the maintenance and recovery circuit accordingly based on the status of the positive and negative fuses.

[0010] The signal circuit is used to acquire and transmit the status information of the positive and negative fuses.

[0011] Preferably, the maintenance and recovery circuit includes:

[0012] The first access branch includes a sixth fuse R6, a second access relay K2, and a ninth fuse R9 connected in series. The first access branch is connected between the first end of the positive fuse R1 and the second end of the negative fuse R2.

[0013] The second access branch includes an eighth fuse R8, a third access relay K3, and a seventh fuse connected in series. The second access branch is connected between the second end of the positive fuse R1 and the first end of the negative fuse R2.

[0014] The first access relay K1 is connected between the sixth fuse R6 and the seventh fuse R7;

[0015] The first parallel branch includes an eleventh fuse R11 and a fourth relay K4 connected in series. The first parallel branch is connected in parallel with the positive fuse R1.

[0016] The second parallel branch includes the twelfth fuse R12 and the fifth relay K5 connected in series. The second parallel branch is connected in parallel with the negative fuse R2.

[0017] The positive terminal fuse R1 is connected to the positive terminal of the first busbar at its first end and to the positive terminal of the battery at its second end; the negative terminal fuse R2 is connected to the negative terminal of the first busbar at its first end and to the negative terminal of the battery at its second end.

[0018] Preferably, the control loop includes at least:

[0019] The first control branch includes the switch Q1, the auxiliary contact of the third access relay K3, the auxiliary contact of the sixth relay, and the auxiliary contact of the fourth relay connected in series.

[0020] The second control branch includes the switch Q1, the auxiliary contact of the second access relay K2, the auxiliary contact of the sixth relay, and the auxiliary contact of the fifth relay connected in series.

[0021] The third control branch includes the auxiliary contacts of the first access relay K1, the second access relay K2, the third access relay K3, and the sixth relay connected in series.

[0022] The first control branch, the second control branch, and the third control branch are connected in parallel. The first end of the parallel connection is connected to the positive terminal of the second busbar through the thirteenth fuse R13; the second end is connected to the negative terminal of the second busbar through the fourteenth fuse R13.

[0023] Preferably, in the normal charging state, when the first access relay K1, the second access relay K2, and the third access relay K3 are in a demagnetized state, their auxiliary contacts are in a closed state; when the voltage across the first access relay K1, the second access relay K2, and the third access relay K3 is greater than a set voltage, they enter an energized state, and their auxiliary contacts are in a closed state, wherein the set voltage is lower than the charging voltage of the battery.

[0024] When the sixth relay K6 is in a demagnetized state, its auxiliary contacts are in a normally closed state.

[0025] When the fourth relay K4 and the fifth relay K5 are in a demagnetized state, their auxiliary contacts are in a normally open state.

[0026] Preferably, the signal loop includes:

[0027] The auxiliary contacts of the second access relay K2 and the third access relay are connected in parallel, and the auxiliary contacts of the sixth relay K6 are connected in series.

[0028] Accordingly, another aspect of the present invention also provides a method for detecting faults in the output fuses of a substation battery bank, which is implemented using the system described above and includes the following steps:

[0029] When the battery is being charged normally, if the charging voltage is higher than the set voltage, the first access relay K1, the second access relay K2, and the third access relay K3 will enter the energized state and their auxiliary contacts will be in the open state, so that the first control circuit, the second control circuit, and the third control circuit will all be in the open state, and the auxiliary contacts of the fourth relay K4 and the fifth relay K5 will all be in the open state.

[0030] When the positive fuse R1 blows, the voltage across the third access relay K3 slowly decreases. When it falls below the set voltage, the third access relay K3 is in a demagnetized state and its auxiliary contacts are closed, thus connecting the first control branch and switching the fourth relay K4 to the energized state. The auxiliary contacts of the fourth relay K4 are connected, thereby connecting the first parallel branch and restoring power supply.

[0031] When the negative fuse R2 blows, the voltage across the second access relay K2 slowly decreases. When it falls below the set voltage, the second access relay K2 is in a demagnetized state, and its auxiliary contacts close. This connects the second control branch, switches the fifth relay K5 to the energized state, and connects the auxiliary contacts of the fifth relay K5, thereby connecting the second parallel branch and restoring power supply.

[0032] Preferably, it further includes:

[0033] When the charger output is locked, the voltages across the first access relay K1, the second access relay K2, and the third access relay K3 all drop below the set voltage. Simultaneously, the first access relay K1, the second access relay K2, and the third access relay K3 are in a demagnetized state, and their auxiliary contacts close. Then, the third control branch is activated, energizing the sixth relay K6, whose auxiliary contacts open, thus disconnecting both the first and second control branches. This demagnetizes the fourth relay K4 and the fifth relay K5 to prevent accidental activation.

[0034] Preferably, it further includes:

[0035] After the positive fuse R1 or the negative fuse R2 blows, the signal circuit generates a fault alarm signal and sends it out.

[0036] Implementing the embodiments of the present invention has the following beneficial effects:

[0037] This invention provides a substation battery bank output fuse fault detection system and method. Through the coordination of maintenance recovery circuits, control circuits, and signal circuits, it can detect the normality of the battery bank output fuses in real time and automatically restore the connection between the battery bank and the DC bus when an abnormality is detected. This prevents the battery bank from disconnecting from the DC system due to an open circuit in the battery bank output fuse. Simultaneously, it can output a "battery bank fuse fault" alarm signal to the monitoring backend.

[0038] Meanwhile, the present invention also has the function of preventing the charger output lockout device from malfunctioning. When there is a short circuit in the DC system, it cannot provide short circuit current, which leads to charger output lockout. Or after the station AC voltage is lost or the charger output is locked out due to other reasons, the whole station can be protected to prevent loss of DC power.

[0039] This invention can be applied to substation DC systems, communication DC systems, and all other DC systems equipped with battery banks. It can automatically detect and restore the connection between the battery bank and the DC bus when a battery output fuse fails, preventing DC system voltage loss due to battery output fuse failure, which could lead to protection lockout and serious accidents such as cascading tripping. It has broad application value and economic benefits. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 A connection diagram of a substation battery bank output fuse fault detection system provided by the present invention;

[0042] Figure 2 for Figure 1 Circuit connection diagram of the maintenance and recovery circuit;

[0043] Figure 3 for Figure 1 A schematic diagram of the circuit connection of the control loop;

[0044] Figure 4 for Figure 1 A schematic diagram of the circuit connection for the signal loop. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0046] like Figure 1 The diagram shows a connection schematic of a substation battery bank output fuse fault detection system provided by the present invention; in conjunction with... Figures 2 to 3 As shown, in this embodiment, the substation battery bank output fuse fault detection system includes at least a maintenance and recovery circuit 1, a control circuit 2, and a signal circuit 3, wherein:

[0047] The maintenance and recovery circuit 1 is connected to both ends of the positive fuse R1 and the negative fuse R2 of the battery pack. It is used to detect the status of the positive fuse R1 and the negative fuse R2. After the positive fuse R1 or the negative fuse R2 blows, it is controlled by the control circuit 2 to connect both ends of the blown positive fuse R1 or the negative fuse R2.

[0048] The control circuit 2 is used to control the maintenance and recovery circuit 1 according to the status of the positive fuse R1 and the negative fuse R2.

[0049] The signal circuit 3 is used to acquire the status information of the positive fuse R1 and the negative fuse R2 and transmit it out.

[0050] More specifically, such as Figure 2 As shown, the maintenance and recovery circuit 1 includes:

[0051] The first access branch includes a sixth fuse R6, a second access relay K2, and a ninth fuse R9 connected in series. The first access branch is connected between the first end of the positive fuse R1 and the second end of the negative fuse R2.

[0052] The second access branch includes an eighth fuse R8, a third access relay K3, and a seventh fuse connected in series. The second access branch is connected between the second end of the positive fuse R1 and the first end of the negative fuse R2.

[0053] The first access relay K1 is connected between the sixth fuse R6 and the seventh fuse R7;

[0054] The first parallel branch includes an eleventh fuse R11 and a fourth relay K4 connected in series. The first parallel branch is connected in parallel with the positive fuse R1.

[0055] The second parallel branch includes the twelfth fuse R12 and the fifth relay K5 connected in series. The second parallel branch is connected in parallel with the negative fuse R2.

[0056] The positive terminal fuse R1 is connected to the positive terminal (+KM1) of the first busbar and to the positive terminal of the battery. The negative terminal fuse R2 is connected to the negative terminal (-KM1) of the first busbar and to the negative terminal of the battery.

[0057] like Figure 3 As shown, the control loop 2 includes at least:

[0058] The first control branch includes a switch Q1 connected in series, an auxiliary contact of the third access relay K3, an auxiliary contact of the sixth relay, and an auxiliary contact of the fourth relay; wherein, the switch Q1 is the main switch for the maintenance and recovery circuit, and when Q1 is disconnected, the function of the maintenance and recovery circuit is deactivated.

[0059] The second control branch includes the switch Q1, the auxiliary contact of the second access relay K2, the auxiliary contact of the sixth relay, and the auxiliary contact of the fifth relay connected in series.

[0060] The third control branch includes the auxiliary contacts of the first access relay K1, the second access relay K2, the third access relay K3, and the sixth relay connected in series.

[0061] The first control branch, the second control branch, and the third control branch are connected in parallel. The first end of the parallel connection is connected to the positive terminal (+KM2) of the second bus through the thirteenth fuse R13; the second end is connected to the negative terminal (-KM2) of the second bus through the fourteenth fuse R13.

[0062] Preferably, during normal charging, when the first access relay K1, the second access relay K2, and the third access relay K3 are in a demagnetized state, their auxiliary contacts are in a closed state; when the voltage across the first access relay K1, the second access relay K2, and the third access relay K3 is greater than a set voltage, they enter an energized state, and their auxiliary contacts are in an open state, wherein the set voltage is lower than the charging voltage of the battery; for example, in a specific example, the charging voltage of the battery is 117V, while the set voltage is 112V;

[0063] When the sixth relay K6 is in a demagnetized state, its auxiliary contacts are in a normally closed state.

[0064] When the fourth relay K4 and the fifth relay K5 are in a demagnetized state, their auxiliary contacts are in a normally open state.

[0065] like Figure 4 As shown, the signal loop 3 includes:

[0066] The auxiliary contacts of the second access relay K2 and the third access relay are connected in parallel, and the auxiliary contacts of the sixth relay K6 are connected in series.

[0067] The working principle of this invention will be illustrated by a specific example below:

[0068] In this invention, relays K1, K2, and K3 are "low voltage" relays with adjustable operating values, relays K4, K5, and K6 are intermediate relays, all relay auxiliary contacts in the control circuit and signal circuit are normally closed, and relays K4 and K5 auxiliary contacts connected to the circuit are normally open.

[0069] This diagram uses a 110V DC system as an example. Under normal operation, the DC system float charge voltage is 117V, and relays K1, K2, and K3 are set to operate at 112V.

[0070] In this system, R1-1 and R1-2 are connected to the two ends of the positive fuse of the battery, and R2-1 and R2-2 are connected to the two ends of the negative fuse of the battery.

[0071] During normal operation, relays K1, K2, and K3 are energized, and their normally closed auxiliary contacts open. Relay K6 is de-energized, and its normally closed auxiliary contact closes. Intermediate relays K4 and K5 are de-energized, and their normally closed auxiliary contacts open. That is, during normal system operation, the third control branch in the control circuit (+-K1-K2-K3-K6--) is disconnected, K6 is de-energized, and its auxiliary contact closes.

[0072] When the positive terminal of the #1 battery pack output fuse fails (R1 fault), the #1 battery pack is disconnected from the #1 DC system. The charger continues to operate normally, and relays K1 and K2 remain energized with their auxiliary contacts open. Because the battery pack cannot be charged in real time to replenish its self-discharge, the battery pack terminal voltage will slowly decrease. When the terminal voltage drops to 112V, relay K3 de-energizes, and its auxiliary contact in the control circuit closes. Simultaneously, relay K6, which remains de-energized, closes its auxiliary contact. At this point, relay K4 is energized, and its auxiliary contact closes, restoring the connection between the battery pack and the DC bus. Simultaneously, the signal circuit is activated after the auxiliary contact of K3 closes, sending a "battery pack fuse fault" signal to the monitoring backend.

[0073] In short, when the output fuse of battery pack #1 fails, the voltage at the pack terminals drops to 112V, causing relay K3 to demagnetize and the auxiliary contact of K3 to close. The first control branch (+-Q1-K3-K6-K4--) circuit is activated, K4 is energized, the auxiliary contact of K4 closes, and the connection between the positive terminal of battery #1, R11, K4, and the positive terminal of the DC system is established, restoring the connection between the battery pack and the DC bus. When the output fuse of battery pack #1 fails, the signal circuit (+-K3-K6--) is activated, sending a "battery pack fuse failure" alarm signal to the monitoring backend.

[0074] This device has the function of preventing the charger output lockout device from malfunctioning. When the charger output is locked out, the battery cannot maintain the charging state, and the voltage at the battery bank terminals drops. Relays K1, K2, and K3 all detect the voltage drop to 112V and are energized. Their auxiliary contacts close, relay K6 is energized, and its auxiliary contact opens, disconnecting the control circuit of relays K4 and K5 to prevent malfunction.

[0075] In simple terms, when the charger output is locked, the battery cannot maintain its charging state, and the battery pack terminal voltage drops. Relays K1, K2, and K3 all detect the voltage drop to 112V and are energized. The third control branch (+-K1-K2-K3-K6--) is turned on, relay K6 is energized, the K6 auxiliary contact is opened, the first control branch (+-Q1-K3-K6-K4--) is opened, and the second control branch (+-Q1-K2-K6-K5--) is opened, which can prevent accidental activation.

[0076] Understandably, this system has a quick-activation / deactivation function by setting the Q1 switch (knife switch), which allows for rapid activation and deactivation of the corresponding functions.

[0077] This invention can be applied to substation DC systems, communication DC systems, and all other DC systems equipped with battery banks. It can automatically detect and restore the connection between the battery bank and the DC bus when a battery output fuse fails, preventing DC system voltage loss due to battery output fuse failure, which could lead to protection lockout and serious accidents such as cascading tripping. It has broad application value and economic benefits.

[0078] Accordingly, another aspect of the present invention also provides a method for detecting faults in the output fuses of a substation battery bank, which employs the methods described above. Figures 1 to 4 The described system is implemented by the following steps:

[0079] When the battery is being charged normally, if the charging voltage is higher than the set voltage, the first access relay K1, the second access relay K2, and the third access relay K3 will enter the energized state and their auxiliary contacts will be in the open state, so that the first control circuit, the second control circuit, and the third control circuit will all be in the open state, and the auxiliary contacts of the fourth relay K4 and the fifth relay K5 will all be in the open state.

[0080] When the positive fuse R1 blows, the voltage across the third access relay K3 slowly decreases. When it falls below the set voltage, the third access relay K3 is in a demagnetized state and its auxiliary contacts are closed, thus connecting the first control branch and switching the fourth relay K4 to the energized state. The auxiliary contacts of the fourth relay K4 are connected, thereby connecting the first parallel branch and restoring power supply.

[0081] When the negative fuse R2 blows, the voltage across the second access relay K2 slowly decreases. When it falls below the set voltage, the second access relay K2 is in a demagnetized state, and its auxiliary contacts close. This connects the second control branch, switches the fifth relay K5 to the energized state, and connects the auxiliary contacts of the fifth relay K5, thereby connecting the second parallel branch and restoring power supply.

[0082] This further includes:

[0083] When the charger output is locked, the voltages across the first access relay K1, the second access relay K2, and the third access relay K3 all drop below the set voltage. Simultaneously, the first access relay K1, the second access relay K2, and the third access relay K3 are in a demagnetized state, and their auxiliary contacts close. Then, the third control branch is activated, energizing the sixth relay K6, whose auxiliary contacts open, thus disconnecting both the first and second control branches. This demagnetizes the fourth relay K4 and the fifth relay K5 to prevent accidental activation.

[0084] This further includes:

[0085] After the positive fuse R1 or the negative fuse R2 blows, the signal circuit generates a fault alarm signal and sends it out.

[0086] For more details, please refer to and combine with the above. Figures 1 to 4 The description of that will not be repeated here.

[0087] Implementing the embodiments of the present invention has the following beneficial effects:

[0088] This invention provides a substation battery bank output fuse fault detection system and method. Through the coordination of maintenance recovery circuits, control circuits, and signal circuits, it can detect the normality of the battery bank output fuses in real time and automatically restore the connection between the battery bank and the DC bus when an abnormality is detected. This prevents the battery bank from disconnecting from the DC system due to an open circuit in the battery bank output fuse. Simultaneously, it can output a "battery bank fuse fault" alarm signal to the monitoring backend.

[0089] Meanwhile, the present invention also has the function of preventing the charger output lockout device from malfunctioning. When there is a short circuit in the DC system, it cannot provide short circuit current, which leads to charger output lockout. Or after the station AC voltage is lost or the charger output is locked out due to other reasons, the whole station can be protected to prevent loss of DC power.

[0090] This invention can be applied to substation DC systems, communication DC systems, and all other DC systems equipped with battery banks. It can automatically detect and restore the connection between the battery bank and the DC bus when a battery output fuse fails, preventing DC system voltage loss due to battery output fuse failure, which could lead to protection lockout and serious accidents such as cascading tripping. It has broad application value and economic benefits.

[0091] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, apparatus, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0092] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device for specifying modules in one or more boxes.

[0093] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A substation battery bank output fuse failure detection system, characterized by, At least comprising a maintenance recovery circuit, a control circuit and a signal circuit, wherein: The maintenance recovery circuit is connected to both ends of the positive and negative fuses of the battery pack, used to detect the state of the positive and negative fuses, and after the positive or negative fuse is fused, under the control of the control circuit, the both ends of the fused positive or negative fuse are connected; The control circuit is used to control the maintenance recovery circuit according to the state of the positive and negative fuses; The signal circuit is used to obtain the state information of the positive and negative fuses and transmit it out; The control circuit at least comprises: The first control branch comprises the switching-on and off switch Q1, the auxiliary contact of the third access relay K3, the auxiliary contact of the sixth relay, and the auxiliary contact of the fourth relay, which are connected in series; The second control branch comprises the switching-on and off switch Q1, the auxiliary contact of the second access relay K2, the auxiliary contact of the sixth relay, and the auxiliary contact of the fifth relay, which are connected in series; The third control branch comprises the auxiliary contact of the first access relay K1, the auxiliary contact of the second access relay K2, the auxiliary contact of the third access relay K3, and the auxiliary contact of the sixth relay, which are connected in series; The first control branch, the second control branch and the third control branch are connected in parallel, and the first end of the parallel connection is connected to the positive pole of the second bus through the thirteenth fuse R13, and the second end is connected to the negative pole of the second bus through the fourteenth fuse R13.

2. The system of claim 1, wherein, The maintenance recovery circuit comprises: The first access branch comprises the sixth fuse R6, the second access relay K2 and the ninth fuse R9, which are connected in series, and the first access branch is connected between the first end of the positive fuse R1 and the second end of the negative fuse R2; The second access branch comprises the eighth fuse R8, the third access relay K3 and the seventh fuse R7, which are connected in series, and the second access branch is connected between the second end of the positive fuse R1 and the first end of the negative fuse R2; The first access relay K1 is connected between the sixth fuse R6 and the seventh fuse R7; The first parallel branch comprises the eleventh fuse R11 and the fourth relay K4, which are connected in series, and the first parallel branch is connected in parallel with the positive fuse R1; The second parallel branch comprises the twelfth fuse R12 and the fifth relay K5, which are connected in series, and the second parallel branch is connected in parallel with the negative fuse R2; The first end of the positive fuse R1 is connected to the positive pole of the first bus, and the second end is connected to the positive pole of the battery; the first end of the negative fuse R2 is connected to the negative pole of the first bus, and the second end is connected to the negative pole of the battery.

3. The detection system of claim 2, wherein, In normal charging state, the auxiliary contact of the first access relay K1, the second access relay K2 and the third access relay K3 is in closed state when the first access relay K1, the second access relay K2 and the third access relay K3 are in de-excitation state; the auxiliary contact of the first access relay K1, the second access relay K2 and the third access relay K3 is in open state when the voltage between the first access relay K1, the second access relay K2 and the third access relay K3 is greater than a set voltage, and the set voltage is lower than the charging voltage of the battery; The auxiliary contact of the sixth relay K6 is in normally closed state when the sixth relay K6 is in de-excitation state. The auxiliary contact of the fourth relay K4 and the fifth relay K5 is in normally open state when the fourth relay K4 and the fifth relay K5 are in de-excitation state.

4. The detection system of claim 3, wherein, The signal circuit comprises: The auxiliary contact of the second access relay K2 and the third access relay K3 is in parallel connection, and the auxiliary contact of the sixth relay K6 is in series connection.

5. A substation battery pack output fuse failure detection method, implemented using the system of any one of claims 3 to 4, characterized in that, The method comprises the following steps: When the battery is normally charged, the charging voltage is higher than the set voltage, the first access relay K1, the second access relay K2 and the third access relay K3 are in excitation state, and the auxiliary contact of the first access relay K1, the second access relay K2 and the third access relay K3 is in open state, so that the first control circuit, the second control circuit and the third control circuit are in open state, and the auxiliary contact of the fourth relay K4 and the fifth relay K5 is in open state; When the positive fuse R1 is fused, the voltage between the third access relay K3 is slowly decreased, and the third access relay K3 is in de-excitation state when the voltage is lower than the set voltage, so that the auxiliary contact of the third access relay K3 is closed; the first control branch is connected, the fourth relay K4 is switched to excitation state, the auxiliary contact of the fourth relay K4 is connected, so that the first parallel branch is connected, and the power supply is restored; When the negative fuse R2 is fused, the voltage between the second access relay K2 is slowly decreased, and the second access relay K2 is in de-excitation state when the voltage is lower than the set voltage, so that the auxiliary contact of the second access relay K2 is closed; the second control branch is connected, the fifth relay K5 is switched to excitation state, the auxiliary contact of the fifth relay K5 is connected, so that the second parallel branch is connected, and the power supply is restored.

6. The method of claim 5, wherein, Further comprising: When the charger output is locked, the voltage between the first access relay K1, the second access relay K2 and the third access relay K3 is decreased to below the set voltage, the first access relay K1, the second access relay K2 and the third access relay K3 are in de-excitation state at the same time, and the auxiliary contact of the first access relay K1, the second access relay K2 and the third access relay K3 is closed; the third control branch is connected, the sixth relay K6 is excited, the auxiliary contact of the sixth relay K6 is opened, the first control branch and the second control branch are both opened, and the fourth relay K4 and the fifth relay K5 are in de-excitation state, so as to prevent misoperation.

7. The method of claim 6, wherein, Further comprising: After the positive fuse R1 or the negative fuse R2 is fused, the signal circuit generates a fault alarm signal and sends it out.

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