Method, system and readable storage medium for detecting abnormality of bridge arm current measurement device

Abstract

The present application belongs to the field of flexible direct current transmission control, and particularly relates to a bridge arm current measurement device abnormality detection method, system and readable storage medium. The present application adopts a constraint condition constructed by a bridge arm current difference value or a bridge arm current change trend to perform judgment, thereby being capable of quickly and accurately identifying bridge arm current measurement device abnormality, perfecting a hidden danger investigation mechanism of valve control equipment, and improving system reliability; protection setting values of each constraint condition can ensure that a fault is detected before other protection tripping when bridge arm current measurement is abnormal; the present application can also ensure that bridge arm current measurement device abnormality protection misoperation is prevented from causing system switching when a grid side and a direct current line are faulty; the present application satisfies that other protection detects a fault before bridge arm current measurement device abnormality protection acts under various faults in a station, avoids a situation that a backup protection is performed instead of tripping action execution; and a protection triggering time set by the present application ensures that redundant depletion protection and valve control imbalance protection are not triggered after bridge arm current measurement device abnormality.

Description

Technical Field

[0001] This invention belongs to the field of flexible DC transmission control, specifically relating to a method, system, and readable storage medium for detecting abnormalities in bridge arm current measuring devices. Background Technology

[0002] In flexible DC transmission valve-controlled systems, the arm current is used for voltage equalization control, circulating current suppression, and arm current protection. Voltage equalization control only uses the direction of the arm current valve, while circulating current suppression and arm current protection only use the magnitude of the arm current. Based on the common configuration of arm current measurement channels, arm current protection uses a two-out-of-three design; therefore, a single channel fault has no impact on arm current protection. However, the valve control system uses an AB system design for voltage equalization and circulating current calculations; therefore, theoretically, a single channel fault will affect voltage equalization and circulating current control.

[0003] However, in existing flexible DC transmission valve control systems, when the arm current measuring device experiences a fault that it cannot detect, although the arm current channel sent by the arm current measuring device to the valve control is still normal and the current quality level is normal, the current measurement value is incorrect, and the specific manifestation is uncertain. It may be always positive, always negative, or alternate between positive and negative. In this case, the valve control will cause submodule voltage equalization function disorder and arm circulating current suppression effect to deteriorate due to abnormal arm current measurement. In severe cases, large-area submodule over- and under-voltage bypass will occur, leading to DC shutdown. Summary of the Invention

[0004] The purpose of this invention is to provide a method, system, and readable storage medium for detecting abnormalities in the arm current measuring device, in order to solve the problem that when the existing flexible DC transmission valve control system malfunctions, the arm current measurement becomes abnormal, resulting in disordered voltage equalization function of the valve control submodule and reduced arm circulating current suppression effect.

[0005] To achieve the above objectives, the present invention provides a method for detecting abnormalities in a bridge arm current measuring device, comprising the following steps:

[0006] Real-time acquisition of current data for each bridge arm collected by the bridge arm current measuring device;

[0007] Based on the current data of each bridge arm, determine whether the changing trend of the bridge arm current meets the constraint conditions.

[0008] If the trend of the bridge arm current meets any one of the constraints, it is determined that an abnormality has been detected in the bridge arm current measuring device.

[0009] The constraint condition includes condition one, which is:

[0010] The sum of the currents of the three-phase upper arm and the sum of the currents of the three-phase lower arm are subtracted, and the absolute value of the difference is greater than the first set current threshold and is maintained for the first set time threshold.

[0011] The beneficial effects of the above technical solution are as follows: by using the characteristics of the bridge arm current difference to diagnose the fault of the bridge arm current measuring device, the shortcomings of making judgments based on circulating current and related electrical quantities of submodule capacitor voltage are avoided. This enables rapid and accurate identification of abnormalities in the bridge arm current measuring device, corresponding effective protection, and improves the hidden danger investigation mechanism of valve control equipment, thereby enhancing the reliability of the system.

[0012] Furthermore, the constraint also includes condition two, which is:

[0013] When the submodules of the converter valve bridge arm remain in the unlocked state, the effective current values ​​of all bridge arms are less than the second set current threshold, and there is a bridge arm whose effective current value does not cross zero within a continuous second set time threshold.

[0014] The beneficial effects of the above technical solution are as follows: by using the characteristics of the change trend of the bridge arm current to judge the fault of the bridge arm current measuring device, the shortcomings of the difficulty or inaccuracy of judging based on the circulating current and the electrical quantities related to the voltage of the sub-module capacitor are avoided. This enables the rapid and accurate identification of abnormalities in the bridge arm current measuring device, the corresponding effective protection is implemented, the hidden danger investigation mechanism of valve control equipment is improved, and the reliability of the system is enhanced.

[0015] Furthermore, the constraint also includes condition three, which is:

[0016] With the submodule of the converter valve bridge arm in the unlocked state, the starting time is the moment when the effective value of all bridge arm currents is less than the third set current threshold. After the starting time, any bridge arm current effective value is less than the fourth set current threshold for a continuous period of the third set time threshold.

[0017] The beneficial effects of the above technical solution are as follows: by using the characteristics of the change trend of the bridge arm current to judge the fault of the bridge arm current measuring device, the shortcomings of the difficulty or inaccuracy of judging based on the circulating current and the electrical quantities related to the voltage of the sub-module capacitor are avoided. This enables the rapid and accurate identification of abnormalities in the bridge arm current measuring device, the corresponding effective protection is implemented, the hidden danger investigation mechanism of valve control equipment is improved, and the reliability of the system is enhanced.

[0018] Furthermore, the settings of the first, second, and third set current thresholds and the first, second, and third set time thresholds simultaneously satisfy the following conditions:

[0019] In the event of grid-side and DC line faults, the converter valve enables fault ride-through;

[0020] The setting of the first time threshold also needs to meet the following conditions simultaneously:

[0021] When the bridge arm current measurement is abnormal, the fault is detected before other types of protection trip.

[0022] Under various fault conditions within the station, other protection systems detect the fault before the abnormal protection of the bridge arm current measuring device operates.

[0023] The beneficial effects of the above technical solution are as follows: it ensures that when the arm current measurement is abnormal, the fault can be reliably detected before other types of protection trip, thus completing the backup protection for the arm current measurement device fault; it ensures that when there are faults on the grid side and DC line, the converter valve can achieve fault ride-through, preventing the abnormal protection of the arm current measurement device from malfunctioning and triggering the backup protection for the arm current measurement device fault; and it can meet the requirements of other protections detecting the fault before the abnormal protection of the arm current measurement device operates under various faults in the station, avoiding the situation where the tripping action is not executed but the backup protection for the arm current measurement device fault is performed instead.

[0024] Furthermore, the method for setting the first, second, and third set current thresholds and the first, second, and third set time thresholds to meet the conditions for the converter valve to achieve fault ride-through when there are grid-side and DC line faults is as follows:

[0025] Simulation scans were performed on different fault types and fault points corresponding to various faults in the station to obtain the corresponding simulation waveforms. Based on the simulation waveforms, the differential current of the bridge arm and the maximum submodule voltage difference under each fault condition were determined.

[0026] Based on the determined bridge arm differential current, the maximum bridge arm differential current is obtained. Based on the simulation waveform corresponding to the maximum bridge arm differential current, the maintenance time corresponding to the differential current value in different ranges is obtained. Then, combined with the maximum submodule voltage difference, the setting range of the first, second, and third set current thresholds and the first, second, and third set time thresholds is determined. Based on the determined setting range, the first, second, and third set current thresholds and the first, second, and third set time thresholds are set.

[0027] Furthermore, to meet the requirements of various faults within the station, the setting method for other protections to detect faults before the abnormal operation of the bridge arm current measuring device is that the first set time threshold is greater than the slowest time of the valve-controlled imbalance protection; and to meet the requirements of the setting method for detecting faults before the tripping of other protections when the bridge arm current measurement is abnormal is that the first set time threshold is less than the fastest time of the overvoltage protection of the converter valve bridge arm submodule.

[0028] The beneficial effects of the above technical solution are as follows: by considering the coordination between the abnormal protection of the measuring device and the overvoltage protection and valve-controlled imbalance protection of the submodule, the first set time threshold is set to ensure that the redundancy depletion protection and valve-controlled imbalance protection will not be triggered after the bridge arm current measuring device malfunctions.

[0029] Furthermore, the various faults within the station include single-phase grounding faults on the grid side of the converter transformer, two-phase short-circuit faults on the grid side of the converter transformer, three-phase short-circuit faults on the grid side of the converter transformer, single-phase grounding faults on the valve side of the converter transformer, two-phase short-circuit faults on the valve side of the converter transformer, three-phase short-circuit faults on the valve side of the converter transformer, single-phase grounding faults on the valve side of the bridge arm reactor, two-phase short-circuit faults on the valve side of the bridge arm reactor, bridge arm flashover, valve top grounding, grounding faults on the valve side of the DC pole bus, grounding faults on the valve side of the neutral line reactor, short-circuit faults between the DC pole bus and the neutral bus reactor valve side, grounding faults on the line side of the neutral line reactor, faults between the DC circuit breaker and the pole line reactor, faults at the beginning and end of the DC pole line, faults in the middle of the DC pole line, and grounding faults on the metallic return line.

[0030] The faults between the DC circuit breaker and the pole line reactor include single-pole grounding faults and pole line and metal return short circuit faults.

[0031] The faults at the beginning and end of the DC pole line include single-pole grounding faults, pole-to-metal return short circuit faults, and bipolar short circuit faults.

[0032] The intermediate faults of the DC pole line include single-pole grounding faults, pole-to-metal return short-circuit faults, and bipolar short-circuit faults.

[0033] Furthermore, if an abnormality is detected in the bridge arm current measuring device, the valve control system is set to self-test abnormality, and a system switch is requested.

[0034] Furthermore, the fourth set current threshold is determined based on the minimum bridge arm current when the submodule of the converter valve bridge arm is unlocked during normal operation of the valve control system.

[0035] The present invention also provides a detection system for abnormality of bridge arm current measuring device, including a processor, the processor being used to execute program instructions to implement the detection method for abnormality of bridge arm current measuring device as described above.

[0036] The detection system for abnormal bridge arm current measuring devices can achieve the same beneficial effects as the aforementioned method for detecting abnormalities in bridge arm current measuring devices.

[0037] The present invention also provides a readable storage medium storing computer-executable instructions, which, when executed, implement the above-described method for detecting abnormalities in the bridge arm current measuring device.

[0038] This readable storage medium can achieve the same beneficial effects as the above-described method for detecting abnormalities in the bridge arm current measuring device. Attached Figure Description

[0039] Figure 1This is a flowchart illustrating the method for detecting abnormalities in the bridge arm current measuring device according to an embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0041] Example of a method for detecting abnormalities in bridge arm current measuring devices

[0042] This embodiment provides a technical solution for detecting abnormalities in a bridge arm current measuring device, referring to... Figure 1 It includes the following steps:

[0043] 1) Real-time acquisition of current data for each bridge arm collected by the bridge arm current measuring device;

[0044] In this embodiment, the bridge arm current measuring device collects the current data of each bridge arm in real time. The collected bridge arm current measurement values ​​are transmitted to the valve control system through an independent optical fiber. Therefore, the valve control system obtains the current data of each bridge arm collected by the bridge arm current measuring device by receiving the data sent by the bridge arm current measuring device.

[0045] 2) Based on the current data of each bridge arm, determine whether the changing trend of the bridge arm current meets the constraint conditions;

[0046] After acquiring the measured values ​​of the bridge arm currents (i.e., the current data of each bridge arm collected by the bridge arm current measuring device), the valve control system calculates the direction and effective value of the currents in the six bridge arms, and checks whether the changing trends of the currents in the six bridge arms meet the constraints corresponding to the correlation constraints. In this embodiment, there are three types of constraints, which are independent of each other, as follows:

[0047] Condition 1 is:

[0048] The sum of the currents of the three-phase upper arm and the sum of the currents of the three-phase lower arm are subtracted. The absolute value of the difference is greater than the first set current threshold I1, that is, |sum of upper arm currents - sum of lower arm currents| > I1, and the first set time threshold T1 is maintained.

[0049] Condition two is:

[0050] When the submodule of the converter valve bridge arm remains in the unlocked state, the effective current value of all bridge arms is less than the second set current threshold I2, and there is a bridge arm whose effective current value does not cross zero within the second set time threshold T2 consecutively.

[0051] Condition three is:

[0052] With the submodule of the converter valve bridge arm in the unlocked state, the starting time is when the effective current value of all bridge arms is less than the third set current threshold I3. After the starting time, if the effective current value of any bridge arm is less than the fourth set current threshold I4 for a continuous third set time threshold T3.

[0053] When the arm current measuring device malfunctions, the electrical quantities related to the sampled arm current, circulating current, and submodule capacitor voltage of the converter valve will all change. However, the change in submodule capacitor voltage cannot cover all operating conditions, and the circulating current change rate is slow and its setpoint is difficult to adjust. Therefore, the arm current difference or the trend of arm current change is used for judgment, i.e., whether conditions one, two, and three are met. This allows for rapid and accurate identification of abnormalities in the arm current measuring device, enabling the corresponding effective protection to be implemented, improving the hidden danger investigation mechanism of valve control equipment, and enhancing the reliability of the system.

[0054] 3) When the trend of the arm current change meets any one of the constraints, it is determined that the arm current measuring device is abnormal, the valve control system performs backup protection and alerts the operator; In this embodiment, if it is determined that the arm current measuring device is abnormal, the valve control system performs backup protection in the following way: the valve control system is set to self-test abnormal and requests system switching; The valve control system usually adopts a redundant configuration, that is, two systems A and B, one active and one standby; Each valve control system is equipped with one arm current measuring device. If the arm current measuring device of the active system is abnormal, it is considered that the device is self-test abnormal, and valve control systems A and B perform system switching, that is, the current active system becomes the standby system, and the current standby system becomes the active system.

[0055] If no abnormality is detected in the arm current measuring device, repeat steps 1)-3) to continue judging the arm current data collected by the arm current measuring device at the next moment.

[0056] Among the set constraints, the first, second, third, and fourth set current thresholds and the first, second, and third set time thresholds satisfy the following conditions:

[0057] In the event of grid-side and DC line faults, the converter valve can achieve fault ride-through, preventing the backup protection (i.e., system switching) from triggering the fault of the bridge arm current measuring device due to abnormal protection malfunction.

[0058] The method for setting the protection settings of each constraint condition to meet the conditions for fault ride-through of the converter valve when the grid-side and DC line faults occur is as follows:

[0059] Simulation scans were performed on different fault types and fault points corresponding to various faults in the station to obtain the corresponding simulation waveforms. Based on the simulation waveforms, the differential current of the bridge arm and the maximum submodule voltage difference under each fault condition were determined.

[0060] Based on the determined bridge arm differential current, the maximum bridge arm differential current is obtained. Based on the simulation waveform corresponding to the maximum bridge arm differential current, the duration corresponding to different ranges of differential current values ​​is obtained. Combined with the maximum submodule voltage difference, the setting ranges of the first, second, and third set current thresholds and the first, second, and third set time thresholds are determined. Specifically, the bridge arm differential currents under various fault conditions are analyzed from the simulation results, and the maximum bridge arm differential current is determined through comparative analysis. The duration corresponding to different ranges of differential current is obtained from the simulation waveform containing this differential current. Combined with the maximum submodule voltage difference, the setting ranges of the first, second, and third set current thresholds and the first, second, and third set time thresholds are determined. Based on the determined setting ranges, the first, second, and third set current thresholds and the first, second, and third set time thresholds are set.

[0061] Among them, the maximum submodule voltage difference is used as a reference value to ensure that the first, second, and third set current thresholds and the first, second, and third set time thresholds determined by the waveform corresponding to the maximum bridge arm differential current do not lead to module overvoltage, thereby further limiting the setting range of these thresholds.

[0062] The fourth current threshold is determined based on the minimum bridge arm current when the submodule of the converter valve bridge arm is unlocked during normal operation of the valve control system.

[0063] The setting of the first time threshold T1 also needs to meet the following conditions:

[0064] (1) Ensure that when the bridge arm current measurement is abnormal, the fault can be reliably detected before other types of protection actions trip, and complete the backup protection (i.e. system switching) for the fault of the bridge arm current measurement device; In this embodiment, considering that the sub-module overvoltage may be triggered, various working conditions are simulated to obtain the shortest time for sub-module overvoltage protection. The setting method that satisfies this condition is that the first set time threshold is less than the shortest time for sub-module overvoltage protection.

[0065] (2) Under various faults in the station, other protections detect the fault before the abnormal protection of the bridge arm current measuring device is activated, so as to avoid the tripping action not being executed but instead performing backup protection (i.e., system switching) for the fault of the bridge arm current measuring device; In this embodiment, considering that the abnormality of the bridge arm current measuring device may trigger the valve control imbalance protection, various working conditions are simulated to obtain the slowest time of valve control imbalance protection under each working condition. The setting method that meets this condition is that the first set time threshold is less than the fastest time of the overvoltage protection of the converter valve bridge arm submodule.

[0066] In this embodiment, simulation scanning is performed on different fault types and fault points, that is, simulation scanning is performed on different fault types and fault points corresponding to various faults within the station; the various faults within the station mainly include the following categories:

[0067] i) Fault in the external communication system:

[0068] Single-phase grounding on the converter transformer side, two-phase short circuit on the converter transformer side, three-phase short circuit on the converter transformer side;

[0069] ii) Internal communication system malfunction:

[0070] Single-phase grounding on the converter transformer valve side, two-phase short circuit on the converter transformer valve side, three-phase short circuit on the converter transformer valve side;

[0071] iii) Valve malfunction:

[0072] Single-phase grounding on the valve side of the bridge arm reactor, two-phase short circuit on the valve side of the bridge arm reactor, bridge arm flashover, and grounding at the valve top;

[0073] iv) Busbar fault:

[0074] DC pole bus valve side grounding fault, neutral line reactor valve side grounding fault, DC pole bus to neutral bus reactor valve side short circuit fault, neutral line reactor line side grounding fault;

[0075] v) Lineside obstruction:

[0076] Faults between DC circuit breakers and pole line reactors: single-pole grounding faults, pole line and metallic return short circuit faults;

[0077] DC pole line start and end faults: single pole grounding fault, pole line and metallic return line short circuit fault, bipolar short circuit fault;

[0078] DC pole line intermediate faults: single pole grounding fault, pole line and metal return line short circuit fault, double pole short circuit fault;

[0079] Metallic return line grounding fault.

[0080] Furthermore, after the bridge arm current measuring device malfunctions, it may trigger the redundancy depletion protection and the valve-controlled imbalance protection. Therefore, it is necessary to consider the coordination between the measuring device malfunction protection and the submodule overvoltage protection and valve-controlled imbalance protection. The setpoint time must be greater than the slowest time of the valve-controlled imbalance protection and less than the fastest time of the submodule overvoltage protection.

[0081] Example of a detection system for abnormal bridge arm current measuring devices

[0082] This embodiment provides a technical solution for a detection system for abnormal bridge arm current measuring devices, including a processor for executing program instructions to implement the detection method steps as described in the above embodiment of the detection method for abnormal bridge arm current measuring devices.

[0083] Since the working method and principle of the detection system for abnormal bridge arm current measuring device in this embodiment have been described in detail in the above embodiment of the detection method for abnormal bridge arm current measuring device, they will not be repeated here.

[0084] Readable storage medium embodiments

[0085] This embodiment provides a readable storage medium storing computer-executable instructions, which, when executed, implement the detection method as described in the above embodiment of the method for detecting abnormalities in a bridge arm current measuring device.

[0086] Since the working mode and principle of the readable storage medium in this embodiment have been described in detail in the above embodiment of the method for detecting abnormalities in the bridge arm current measuring device, they will not be repeated here.

[0087] This invention has the following characteristics:

[0088] ① The system uses constraints constructed by the difference in bridge arm current or the trend of bridge arm current change to make judgments, namely, whether conditions one, two, and three are met; this enables the rapid and accurate identification of abnormalities in the bridge arm current measuring device, the corresponding effective protection, and the improvement of the hidden danger investigation mechanism of valve control equipment, thereby enhancing the reliability of the system.

[0089] ② The protection settings of each constraint condition can ensure that when the arm current measurement is abnormal, the fault can be reliably detected before other types of protection trip, and the backup protection for the arm current measurement device fault can be completed; it can also ensure that the converter valve can achieve fault ride-through when there is a fault on the grid side and DC line, preventing the abnormal protection of the arm current measurement device from causing system switching, and can meet the requirements of other protections to detect the fault before the abnormal protection of the arm current measurement device operates under various faults in the station, avoiding the situation where the tripping action is not executed but the backup protection for the arm current measurement device fault is performed instead.

[0090] ③ Consider the coordination between the abnormal protection of the bridge arm current measuring device and the overvoltage protection and valve-controlled imbalance protection of the submodule, and set the first set time threshold for triggering the abnormal protection of the bridge arm current measuring device to ensure that the redundancy depletion protection and valve-controlled imbalance protection will not be triggered after the abnormality of the bridge arm current measuring device.

[0091] It should be understood that the above-described specific embodiments of the present invention are merely illustrative or explanatory of the principles of the present invention, and do not constitute a limitation thereof.

Claims

1. A method for detecting abnormalities in a bridge arm current measuring device, characterized in that, Includes the following steps: Real-time acquisition of current data for each bridge arm collected by the bridge arm current measuring device; Based on the current data of each bridge arm, determine whether the changing trend of the bridge arm current meets the constraint conditions. If the trend of the bridge arm current meets any one of the constraints, it is determined that an abnormality has been detected in the bridge arm current measuring device. The constraint condition includes condition one, which is: The sum of the currents of the three-phase upper arm and the sum of the currents of the three-phase lower arm are subtracted, and the absolute value of the difference is greater than the first set current threshold and is maintained for the first set time threshold.

2. The method for detecting abnormalities in the bridge arm current measuring device according to claim 1, characterized in that, The constraint also includes condition two, which is: When the submodules of the converter valve bridge arm remain in the unlocked state, the effective current values ​​of all bridge arms are less than the second set current threshold, and there is a bridge arm whose effective current value does not cross zero within a continuous second set time threshold.

3. The method for detecting abnormalities in the bridge arm current measuring device according to claim 2, characterized in that, The constraint also includes condition three, which is: With the submodule of the converter valve bridge arm in the unlocked state, the starting time is the moment when the effective current value of all bridge arms is less than the third set current threshold. After the starting time, if the effective current value of any bridge arm is less than the fourth set current threshold for a continuous period of the third set time threshold.

4. The method for detecting abnormalities in the bridge arm current measuring device according to claim 3, characterized in that, The settings of the first, second, and third current thresholds and the first, second, and third time thresholds simultaneously satisfy the following conditions: In the event of grid-side and DC line faults, the converter valve enables fault ride-through; The setting of the first time threshold also needs to meet the following conditions simultaneously: When the bridge arm current measurement is abnormal, the fault is detected before other types of protection trip. Under various fault conditions within the station, other protection systems detect the fault before the abnormal protection of the bridge arm current measuring device operates.

5. The method for detecting abnormalities in the bridge arm current measuring device according to claim 4, characterized in that, The method for setting the first, second, and third set current thresholds and the first, second, and third set time thresholds to meet the conditions for the converter valve to achieve fault ride-through when there are grid-side and DC line faults is as follows: Simulation scans were performed on different fault types and fault points corresponding to various faults in the station to obtain the corresponding simulation waveforms. Based on the simulation waveforms, the differential current of the bridge arm and the maximum submodule voltage difference under each fault condition were determined. Based on the determined bridge arm differential current, the maximum bridge arm differential current is obtained. Based on the simulation waveform corresponding to the maximum bridge arm differential current, the maintenance time corresponding to the differential current value in different ranges is obtained. Then, combined with the maximum submodule voltage difference, the setting range of the first, second, and third set current thresholds and the first, second, and third set time thresholds is determined. Based on the determined setting range, the first, second, and third set current thresholds and the first, second, and third set time thresholds are set.

6. The method for detecting abnormalities in the bridge arm current measuring device according to claim 4 or 5, characterized in that, To ensure that, under various fault conditions within the station, other protection systems detect faults before the abnormal operation of the bridge arm current measuring device protection, the first set time threshold is greater than the slowest time of the valve-controlled imbalance protection; and to ensure that, when the bridge arm current measurement is abnormal, other protection systems detect faults before tripping, the first set time threshold is less than the fastest time of the converter valve bridge arm submodule overvoltage protection.

7. The method for detecting abnormalities in the bridge arm current measuring device according to claim 4, characterized in that, The various faults within the station include: single-phase grounding fault on the grid side of the converter transformer, two-phase short-circuit fault on the grid side of the converter transformer, three-phase short-circuit fault on the grid side of the converter transformer, single-phase grounding fault on the valve side of the converter transformer, two-phase short-circuit fault on the valve side of the converter transformer, three-phase short-circuit fault on the valve side of the converter transformer, single-phase grounding fault on the valve side of the bridge arm reactor, two-phase short-circuit fault on the valve side of the bridge arm reactor, bridge arm flashover, valve top grounding, grounding fault on the valve side of the DC pole bus, grounding fault on the valve side of the neutral line reactor, short-circuit fault between the DC pole bus and the neutral bus reactor valve side, grounding fault on the line side of the neutral line reactor, fault between the DC circuit breaker and the pole line reactor, fault at the beginning and end of the DC pole line, fault in the middle of the DC pole line, and grounding fault of the metallic return line. The faults between the DC circuit breaker and the pole line reactor include single-pole grounding faults and pole line and metal return short circuit faults. The faults at the beginning and end of the DC pole line include single-pole grounding faults, pole-to-metal return short circuit faults, and bipolar short circuit faults. The intermediate faults of the DC pole line include single-pole grounding faults, pole-to-metal return short-circuit faults, and bipolar short-circuit faults.

8. The method for detecting abnormalities in the bridge arm current measuring device according to any one of claims 1-5, characterized in that, If an abnormality is detected in the bridge arm current measuring device, the valve control system will be set to self-test abnormality and a system switch will be requested.

9. The method for detecting abnormalities in the bridge arm current measuring device according to claim 3, wherein the fourth set current threshold is determined based on the minimum bridge arm current value when the submodule of the converter valve bridge arm is unlocked during normal operation of the valve control system.

10. A detection system for abnormalities in a bridge arm current measuring device, characterized in that, Includes a processor for executing program instructions to implement the method for detecting abnormalities in the bridge arm current measuring device as described in any one of claims 1-9.

11. A readable storage medium storing computer-executable instructions, characterized in that, The computer-executable instructions, when executed, implement the method for detecting abnormalities in the bridge arm current measuring device as described in any one of claims 1-9.

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