Converter valve power submodule state detection method and system

Abstract

The invention relates to a power submodule state detection method and system of a converter valve, and belongs to the technical field of direct current transmission. When an instruction used for controlling the bypass switch of the sub-module to be closed is issued and the closing state of the bypass switch detected by the state detection loop is not sent, if the set condition that the capacitor voltage of the sub-module is greater than or equal to the rated operating voltage of the sub-module or the appearance of the bypass switch detects that the bypass switch is not closed is met, the sub-module is switched on. If yes, determining that the sub-module bypass switch is switched on abnormally; if the capacitor voltage of the sub-module is smaller than the rated operating voltage of the sub-module or it is detected that the bypass switch is closed through the appearance of the bypass switch, it is judged that uploading of the closing state of the bypass switch by the state detection loop is abnormal; when the instruction is not issued and the switching-on state is uploaded, if a set condition is met, the state detection loop is judged to be abnormal; and if the capacitor voltage of the sub-module is smaller than the rated operating voltage or the bypass switch is detected to be closed through the appearance of the bypass switch, judging that the bypass switch of the sub-module is in maloperation.

Description

Technical Field

[0001] The present invention relates to a method and system for detecting the state of a power sub-module of a converter valve, belonging to the technical field of HVDC transmission. Background Art

[0002] In China, the maintenance system of power equipment has long been mainly based on regular planned maintenance supplemented by after-fact maintenance. The fault characteristics of power equipment in each stage of its life cycle are different, which determines that the maintenance cycle of planned maintenance should consider the entire life cycle of the equipment, deeply excavate and analyze the operation data of the equipment, and clarify the law of fault occurrence, so as to improve the maintenance efficiency.

[0003] The flexible DC converter valve (referred to as the flexible DC converter valve for short) is the core equipment of the flexible DC transmission project. The flexible DC converter valve is mainly applied in the flexible DC transmission system. An example diagram of the topological structure of the flexible DC transmission system is as Figure 1 shown. Its topological structure consists of 6 bridge arms (i.e., Figure 1 3 upper bridge arms and 3 lower bridge arms in Figure 1 ), and each bridge arm has the same number of power sub-modules ( the single sub-module in

[0004] is the single power sub-module) and a bridge arm reactor. The power sub-module adopts a full-bridge or half-bridge structure. Among them, the power sub-module is an important part of the flexible DC converter valve. However, since the existing flexible DC projects have been in operation for a short time, there is a lack of long-term operation data accumulation and experience summary. Therefore, at present, most of the detections of the power sub-modules of the flexible DC converter valve adopt traditional regular detection and maintenance means; however, this regular detection and maintenance means is difficult to timely and comprehensively detect the abnormalities or faults of the converter valve power sub-module, and there are potential safety hazards.

[0005] The present invention aims to provide a method and system for detecting the state of a power sub-module of a converter valve to solve the problem that the current regular detection and maintenance means are difficult to timely and comprehensively detect the abnormalities or faults of the converter valve power sub-module, and there are potential safety hazards. When the instruction is not issued and the closing state has been sent, if the set conditions are met, it is determined that the status detection circuit is abnormal; if the capacitor voltage of the sub-module is less than the rated operating voltage of the sub-module or it is detected through the appearance of the bypass switch that the bypass switch is closed, it is determined that the bypass switch of the sub-module malfunctions.

[0006] Furthermore, it also includes: When the attenuation rate of the capacitance value of the power sub-module capacitor compared to the average value of the capacitance values of all power sub-module capacitors on the arm where the power sub-module is located is greater than the set attenuation rate of the capacitance value, and the attenuation rate compared to the initial value of the capacitance value of the power sub-module is greater than the first attenuation rate, and at the same time, the change rate of the capacitor voltage of the power sub-module compared to the rated value of the capacitor voltage is not within the set capacitor voltage change rate range, it is determined that the power sub-module capacitor is abnormal; The set attenuation rate of the capacitance value is greater than or equal to 3%; the first attenuation rate is greater than or equal to 5%, and the set capacitor voltage change rate range is [-10%, 10%].

[0007] Furthermore, it also includes: When the increase in the temperature of the power sub-module capacitor compared to the average value of the temperatures of all power sub-module capacitors on the arm where the power sub-module is located is greater than the set increase in capacitor temperature and the temperature of the power sub-module capacitor is greater than the first capacitor temperature threshold, and at the same time, the increase in the temperature of the radiator of the power sub-module compared to the average value of the temperatures of all power sub-module radiators on the arm where the power sub-module is located is greater than the set increase in radiator temperature and the temperature of the radiator of the power sub-module is greater than the first set value of radiator temperature, it is determined that the capacitor of the power sub-module is abnormal; The set increase in capacitor temperature is greater than or equal to 10°C, the first capacitor temperature threshold is greater than or equal to 50°C, the set increase in radiator temperature is greater than or equal to 10°C, and the first set value of radiator temperature is greater than or equal to 50°C.

[0008] Furthermore, it also includes: When the attenuation rate of the capacitance value of the power sub-module capacitor compared to the average value of the capacitance values of all power sub-module capacitors on the arm where the power sub-module is located is greater than the set attenuation rate of the capacitance value and the attenuation rate compared to the initial value of the capacitance value of the power sub-module is greater than the second attenuation rate, and at the same time, the change rate of the capacitor voltage of the power sub-module compared to the rated value of the capacitor voltage is not within the set capacitor voltage change rate range, it is determined that the power sub-module capacitor fails; The second attenuation rate is greater than or equal to 6%.

[0009] Furthermore, it also includes: When the increase in the temperature of the capacitor of the power sub-module compared to the average value of the capacitor temperatures of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in capacitor temperature and the temperature of the capacitor of the power sub-module is greater than the second capacitor temperature threshold, and at the same time, the increase in the temperature of the radiator of the power sub-module compared to the average value of the radiator temperatures of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in radiator temperature and the temperature of the radiator of the power sub-module is greater than the first set value of radiator temperature, then it is determined that the capacitor of the power sub-module fails; The second capacitor temperature threshold is greater than or equal to 60°C.

[0010] Furthermore, it also includes: When any one of the on-state saturation voltage drop of the IGBT of the power sub-module, the switching frequency of the IGBT, the junction temperature of the IGBT, and the radiator temperature meets the corresponding set conditions, then it is determined that the IGBT is abnormal; The set condition for the on-state saturation voltage drop of the IGBT is that the growth rate compared to the average value of the on-state saturation voltage drops of all IGBTs on the arm where the power sub-module is located is greater than the set growth rate of the on-state saturation voltage drop of the IGBT; The set condition for the switching frequency of the IGBT is that it is greater than the set value of the switching frequency of the IGBT; The set condition for the junction temperature of the IGBT is that it is greater than the set junction temperature and the increase compared to the junction temperatures of all IGBTs on the arm where the power sub-module is located is greater than the set increase in junction temperature; The set condition for the radiator temperature is that it is greater than the second set value of the radiator temperature, and the increase compared to the average value of the radiator temperatures of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in radiator temperature; The set growth rate of the on-state saturation voltage drop of the IGBT is greater than or equal to 20%, the set value of the switching frequency of the IGBT is greater than 500 Hz, the set junction temperature is greater than or equal to 110°C, the set increase in junction temperature is greater than or equal to 10°C, and the second set value of the radiator temperature is greater than or equal to 70°C.

[0011] Furthermore, it also includes: If the number of times of communication failure between the power sub-module and the valve control device is greater than the set number of times, then it is determined that the communication of the power sub-module is abnormal.

[0012] Beneficial effects: The present invention provides a new method for detecting the state of a power sub-module of a converter valve. When an instruction for controlling the closing of the bypass switch of the sub-module has been issued and the closing state of the bypass switch detected through the state detection circuit has not been sent, if the capacitor voltage of the sub-module is greater than or equal to the rated operating voltage of the sub-module (if the capacitor voltage of the sub-module is greater than or equal to the rated operating voltage of the sub-module, it indicates that the bypass switch of the sub-module is not closed at this time) or it is detected through the appearance of the bypass switch that the bypass switch is not closed, it is determined that the closing of the bypass switch is abnormal; if the capacitor voltage of the sub-module is less than the rated operating voltage of the sub-module or it is detected through the appearance of the bypass switch that the bypass switch is closed, it is determined that the sending of the closing state of the bypass switch by the state detection circuit is abnormal; when an instruction for controlling the closing of the bypass switch of the sub-module has not been issued and the closing state of the bypass switch detected through the state detection circuit has been sent, if the capacitor voltage of the sub-module is greater than or equal to the rated operating voltage of the sub-module or it is detected through the appearance of the bypass switch that the bypass switch is not closed, it indicates that no closing instruction has been issued at this time and the bypass switch is actually not closed, but the closing state detected through the bypass switch state detection circuit has been sent, it is determined that the state detection circuit is abnormal; if the capacitor voltage of the sub-module is less than the rated operating voltage of the sub-module or it is detected through the appearance of the bypass switch that the bypass switch is closed; it indicates that no instruction has been issued at this time, but actually the bypass switch is closed, and the closing state of the bypass switch detected through the state detection circuit has been sent, it is determined that the bypass switch of the sub-module has malfunctioned; therefore, compared with the existing detection means, this method analyzes and judges the issuance situation of the closing instruction of the bypass switch of the converter valve sub-module, the sending situation of the closing state detected through the bypass switch state detection circuit, the appearance detection result of the bypass switch, and the capacitor voltage of the sub-module respectively, and can timely and comprehensively judge the abnormal situation of the bypass switch of the sub-module, that is, judge which type of abnormality the abnormality of the bypass switch of the sub-module belongs to, namely, the actual opening and closing abnormality of the bypass switch, the sending abnormality of the closing state of the bypass switch by the state detection circuit, the state detection circuit abnormality, and the malfunction of the bypass switch of the sub-module; thus, it can be seen that this method can timely and comprehensively distinguish the state of the bypass switch, and has stronger safety.

[0013] The present invention also provides a system for detecting the state of a power sub-module of a converter valve, including a processor, and the processor is used to execute computer program instructions to implement the steps of the above method for detecting the state of a power sub-module of a converter valve.

[0014] The system for detecting the state of a power sub-module of the converter valve can achieve the same beneficial effects as the above method for detecting the state of a power sub-module of the converter valve. Description of the Drawings

[0015] Figure 1 is an exemplary diagram of the topology structure of a flexible DC power transmission system in the background art of the present invention; Figure 2It is a flowchart for detecting the state of the bypass switch in the power sub-module of the converter valve in the embodiment of the method for detecting the state of the power sub-module of the present invention; Figure 3 It is a flowchart for detecting the state of the capacitor in the power sub-module of the converter valve in the embodiment of the method for detecting the state of the power sub-module of the present invention; Figure 4 It is a flowchart for detecting the state of the IGBT in the power sub-module of the converter valve in the embodiment of the method for detecting the state of the power sub-module of the present invention. Detailed implementation manners

[0016] The following further describes the detailed implementation manners of the present invention with reference to the accompanying drawings.

[0017] Embodiment of the method for detecting the state of the power sub-module of the converter valve This embodiment provides a technical solution for a method for detecting the state of the power sub-module of a converter valve. This method analyzes and judges through the issuance situation of the closing instruction of the bypass switch of the converter valve sub-module, the sending situation of the closing state detected by the bypass switch state detection circuit, the appearance detection result of the bypass switch, and the capacitor voltage of the sub-module, and can timely and comprehensively judge the abnormal situation of the sub-module bypass switch, that is, judge which type of abnormality the abnormality of the sub-module bypass switch belongs to among the actual on-off abnormality of the bypass switch, the sending abnormality of the closing state of the bypass switch by the state detection circuit, the state detection circuit abnormality, and the misoperation of the sub-module bypass switch; the safety is stronger.

[0018] The method specifically includes: when the instruction for controlling the closing of the sub-module bypass switch has been issued and the closing state of the bypass switch detected by the state detection circuit has not been sent, if the set condition that the capacitor voltage of the sub-module is greater than or equal to the rated operating voltage of the sub-module or the bypass switch is detected to be not closed by the appearance of the bypass switch is satisfied, it is determined that the closing of the sub-module bypass switch is abnormal; if the capacitor voltage of the sub-module is less than the rated operating voltage of the sub-module or the bypass switch is detected to be closed by the appearance of the bypass switch, it is determined that the sending of the closing state of the bypass switch by the state detection circuit is abnormal; When the instruction for controlling the closing of the sub-module bypass switch is not issued and the closing state of the bypass switch detected by the status detection circuit has been sent, if the set condition that the module capacitor voltage is greater than or equal to the rated operating voltage of the sub-module or the bypass switch is detected as not closed by visually inspecting the bypass switch is met, it is determined that the status detection circuit is abnormal; if the sub-module capacitor voltage is less than the rated operating voltage of the sub-module or the bypass switch is detected as closed by visually inspecting the bypass switch, it is determined that the sub-module bypass switch has malfunctioned. By analyzing and judging the issuance of the closing instruction of the bypass switch of the converter valve sub-module, the sending of the closing state detected by the bypass switch status detection circuit, the visual inspection result of the bypass switch, and the sub-module capacitor voltage, this method can timely and comprehensively determine the status of the bypass switch, with stronger safety.

[0019] The power sub-module status detection method of the converter valve in this embodiment will be specifically described below: The flowchart for detecting the status of the bypass switch in the power sub-module of the converter valve is as Figure 2 shown, Figure 2 The sub-module mentioned herein refers to the power sub-module of the converter valve. When the instruction for controlling the closing of the sub-module bypass switch (the instruction for controlling the closing of the sub-module bypass switch corresponds to the bypass switch closing instruction in Figure 2 ) has been issued and the closing state of the bypass switch detected by the status detection circuit has not been sent, if the set condition that the sub-module capacitor voltage is greater than or equal to the rated operating voltage of the sub-module (the sub-module capacitor voltage being greater than or equal to the rated operating voltage of the sub-module corresponds to no abnormality in the sub-module capacitor voltage in Figure 2 ) or the bypass switch is detected as not closed by visually inspecting the bypass switch is met, it is determined that the closing of the sub-module bypass switch is abnormal; if the sub-module capacitor voltage is less than the rated operating voltage of the sub-module (the sub-module capacitor voltage being less than the rated operating voltage of the sub-module corresponds to a significant decrease in the sub-module capacitor voltage in Figure 2 ) or the bypass switch is detected as closed by visually inspecting the bypass switch, it is determined that the sending of the closing state of the bypass switch by the status detection circuit is abnormal; in this embodiment, the status detection circuit is the bypass switch auxiliary node circuit, and the function of the bypass switch auxiliary node circuit is to ensure the accurate operation and status feedback of the bypass switch. The bypass switch auxiliary node circuit includes detection elements installed near the bypass switch contacts or operating mechanism, and the opening and closing state of the bypass switch is judged based on the data sampled by the detection elements, without specific limitation; in this embodiment, the method for visually inspecting the bypass switch is specifically to detect whether the bypass switch is closed by identifying the monitoring video of the bypass switch, and the visual inspection of the bypass switch corresponds to the video detection in Figure 2 ; among them, the bypass switch closing state corresponds to the bypass switch closed position state in Figure 2 . When the instruction for controlling the closing of the sub-module bypass switch is not issued and the closing state of the bypass switch detected by the status detection circuit has been sent, if the set conditions that the sub-module capacitor voltage is greater than or equal to the rated operating voltage of the sub-module or the bypass switch is detected as not closed by the appearance of the bypass switch are met, it is determined that the status detection circuit is abnormal (the abnormality of the status detection circuit corresponds to the abnormality of the auxiliary node circuit in Figure 2 ); if the sub-module capacitor voltage is less than the rated operating voltage of the sub-module or the bypass switch is detected as closed by the appearance of the bypass switch, it is determined that the sub-module bypass switch has malfunctioned.

[0020] In this embodiment, the power sub-module status detection method of the converter valve further includes: detecting the capacitor status in the power sub-module of the converter valve; the flowchart of detecting the capacitor status in the power sub-module of the converter valve is as Figure 3 shown. Figure 3 The sub-module and module mentioned in Figure 3 both refer to the power sub-module of the converter valve. When the attenuation rate of the capacitance value of the power sub-module capacitor compared to the average value of the capacitance values of all power sub-module capacitors on the arm where the power sub-module is located is greater than the set attenuation rate of the capacitance value (the set attenuation rate of the capacitance value is greater than or equal to 3%, and in this embodiment, the set attenuation rate of the capacitance value is 3%), and the attenuation rate compared to the initial value of the capacitance value of the power sub-module is greater than the first attenuation rate (the first attenuation rate is greater than or equal to 5%, and in this embodiment, the first attenuation rate is 5%), and at the same time, the change rate of the capacitor voltage (the capacitor voltage corresponds to the Figure 3 capacitance voltage in Figure 3 ) of the power sub-module compared to the rated value of the capacitance voltage is not within the set capacitance voltage change rate range (in this embodiment, the set capacitance voltage change rate range is [-10%, 10%]), it is determined that the power sub-module capacitor is abnormal; among them, the initial value of the capacitance value of the power sub-module is obtained through a capacitance measuring instrument. In this embodiment, when the increase in the temperature of the capacitor of the power sub-module compared to the average temperature of the capacitors of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in capacitor temperature (the set increase in capacitor temperature is greater than or equal to 10°C, and in this embodiment, the set increase in capacitor temperature is taken as 10°C), and the temperature of the capacitor of the power sub-module is greater than the first capacitor temperature threshold (the first capacitor temperature threshold is greater than or equal to 50°C, and in this embodiment, the first capacitor temperature threshold is taken as 50°C), at the same time, when the increase in the temperature of the radiator of the power sub-module compared to the average temperature of the radiators of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in radiator temperature (the set increase in radiator temperature is greater than or equal to 10°C, and in this embodiment, the set increase in radiator temperature is taken as 10°C), and the temperature of the radiator of the power sub-module is greater than the first set radiator temperature value (the first set radiator temperature value is greater than or equal to 50°C, and in this embodiment, the first set radiator temperature value is taken as 50°C), then it is determined that the capacitor of the power sub-module is abnormal; In this embodiment, when the attenuation rate of the capacitance value of the capacitor of the power sub-module compared to the average capacitance value of the capacitors of all power sub-modules on the arm where the power sub-module is located is greater than the set attenuation rate of the capacitance value (the set attenuation rate of the capacitance value is greater than or equal to 3%, and in this embodiment, the set attenuation rate of the capacitance value is taken as 3%), and the attenuation rate compared to the initial capacitance value of the power sub-module is greater than the second attenuation rate (the second attenuation rate is greater than or equal to 6%, and in this embodiment, the second attenuation rate is taken as 6%), at the same time, when the change rate of the capacitor voltage of the power sub-module is not within the set capacitor voltage change rate range (the set capacitor voltage change rate range is [-10%, 10%]), then it is determined that the capacitor of the power sub-module fails; In this embodiment, when the increase in the temperature of the capacitor of the power sub-module compared to the average temperature of the capacitors of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in capacitor temperature (the set increase in capacitor temperature is greater than or equal to 10°C, and in this embodiment, the set increase in capacitor temperature is taken as 10°C), and the temperature of the capacitor of the power sub-module is greater than the second capacitor temperature threshold (the second capacitor temperature threshold is greater than or equal to 60°C, and in this embodiment, the second capacitor temperature threshold is taken as 60°C), at the same time, when the increase in the temperature of the radiator of the power sub-module compared to the average temperature of the radiators of all power sub-modules on the arm where the power sub-module is located is greater than the set increase in radiator temperature and the temperature of the radiator of the power sub-module is greater than the first set radiator temperature value (in this embodiment, the first set radiator temperature value is taken as 50°C), then it is determined that the capacitor of the power sub-module fails. In this embodiment, by analyzing and judging the changes in the capacitance value, capacitor temperature, and radiator temperature of the power sub-module capacitor, the abnormal faults of the power sub-module capacitor can be judged in a timely and comprehensive manner.

[0021] In this embodiment, the method for detecting the state of the power sub-module of the converter valve further includes: detecting the state of the IGBT in the power sub-module of the converter valve. The flowchart for detecting the state of the IGBT in the power sub-module of the converter valve is as Figure 4 shown. Figure 4 The sub-module mentioned above is the power sub-module of the converter valve. The method for detecting the state of the IGBT in the power sub-module of the converter valve includes: when any one of the on-state saturation voltage drop of the IGBT in the power sub-module, the switching frequency of the IGBT, the junction temperature of the IGBT, and the radiator temperature satisfies the corresponding set condition, it is determined that the IGBT is abnormal; The set condition corresponding to the on-state saturation voltage drop of the IGBT is that the growth rate compared to the average value of the on-state saturation voltage drops of all the IGBTs on the arm where the power sub-module is located (this average value corresponds to Figure 4 the "corresponding average value of the on-state saturation voltage drop" in is greater than the set growth rate of the on-state saturation voltage drop of the IGBT. The set growth rate of the on-state saturation voltage drop of the IGBT is greater than or equal to 20%. In this embodiment, the set growth rate of the on-state saturation voltage drop of the IGBT is taken as 20%; The set condition corresponding to the switching frequency of the IGBT is greater than the set value of the switching frequency of the IGBT (the set value of the switching frequency of the IGBT corresponds to Figure 4 D1 in ), and the set value of the switching frequency of the IGBT is greater than 500 Hz; The set condition corresponding to the junction temperature of the IGBT is greater than the set junction temperature (the set junction temperature corresponds to Figure 4 D2 in ), the set junction temperature is greater than or equal to 110 °C. In this embodiment, the set junction temperature is taken as 110 °C, and the increase compared to the average value of the junction temperatures of all the IGBTs on the arm where the power sub-module is located (this average value corresponds to Figure 4 the "corresponding average junction temperature" in ) is greater than the set increase in the junction temperature. The set increase in the junction temperature is greater than or equal to 10 °C. In this embodiment, the set increase in the junction temperature is taken as 10 °C; The set condition corresponding to the radiator temperature is greater than the second set value of the radiator temperature (the second set value of the radiator temperature corresponds to Figure 4 D3 in ), the second set value of the radiator temperature is greater than or equal to 70 °C. In this embodiment, the second set value of the radiator temperature is taken as 70 °C, and the increase compared to the average value of the radiator temperatures of all the power sub-modules on the arm where the power sub-module is located (this average value corresponds to Figure 4 the "corresponding average radiator temperature" in ) is greater than the set increase in the radiator temperature. The set increase in the radiator temperature is greater than or equal to 10 °C. In this embodiment, the set increase in the radiator temperature is taken as 10 °C.

[0022] In this embodiment, the method for detecting the state of the power sub-module of the converter valve further includes: if the number of times of communication failure between the power sub-module and the valve control device is greater than the set number of times, it is determined that the communication of the power sub-module is abnormal. Among them, the communication abnormality of the power sub-module is generally caused by abnormalities in optical fibers or boards.

[0023] Figure 4 The "horizontal and vertical comparison" in [] means to search for the power sub-module horizontally and vertically; the modules and sub-modules mentioned in this embodiment both refer to the power sub-modules of the converter valve.

[0024] Embodiment of the system for detecting the state of the power sub-module of the converter valve This embodiment provides a technical solution for a system for detecting the state of the power sub-module of a converter valve. The system includes a processor, and the processor is used to execute a computer program to implement the steps of the method for detecting the state of the power sub-module of the converter valve.

[0025] Since the specific implementation process and principle of the system for detecting the state of the power sub-module of the converter valve in this embodiment have been described in detail in the embodiment of the method for detecting the state of the power sub-module of the converter valve, no further elaboration will be provided here.

[0026] It should be understood that the above specific embodiments of the present invention are only used for illustrative explanation or interpretation of the principle of the present invention, and do not constitute a limitation to the present invention.

Claims

1. A method for detecting the state of a power submodule of a converter valve, characterized in that: include: When the instruction for controlling the closing of the bypass switch of the submodule has been issued and the closing state of the bypass switch detected by the state detection loop has not been sent up, if the setting conditions that the submodule capacitor voltage is greater than or equal to the rated operating voltage of the submodule or the bypass switch is not closed by the appearance of the bypass switch are met, it is determined that the closing of the bypass switch of the submodule is abnormal; If the submodule capacitor voltage is less than the rated operating voltage of the submodule or the bypass switch is detected to be closed through the appearance of the bypass switch, it is determined that the state detection circuit is abnormal in sending the closing state of the bypass switch; When the instruction has not been issued and the closing state has been sent up, if the set condition is met, it is determined that the state detection circuit is abnormal; If the submodule capacitor voltage is less than the rated operating voltage of the submodule or the bypass switch is detected to be closed through the appearance of the bypass switch, it is determined that the submodule bypass switch is malfunctioning.

2. The power submodule state detection method of the converter valve according to claim 1, characterized in that: Also includes: When the attenuation rate of the capacitance of the power sub-module capacitor compared to the average capacitance of the capacitors of all the power sub-modules on the bridge arm where the power sub-module is located is greater than the set attenuation rate of the capacitance of the capacitor, and the attenuation rate compared to the initial value of the capacitance of the power sub-module is greater than the first attenuation rate, and at the same time, the change rate of the capacitor voltage of the power sub-module compared to the rated value of the capacitor voltage is not within the set capacitor voltage change rate range, then it is determined that the capacitor of the power sub-module is abnormal; The set attenuation rate of the capacitor capacitance is greater than or equal to 3%; the first attenuation rate is greater than or equal to 5%, and the setting capacitor voltage change rate range is [-10%, 10%].

3. The power submodule state detection method of a converter valve according to claim 1 or 2, characterized in that: Also includes: When the increase of the temperature of the capacitor of the power submodule compared to the average value of the capacitor temperatures of all the power submodules on the bridge arm where the power submodule is located is greater than the set increase of the capacitor temperature and the temperature of the capacitor of the power submodule is greater than the first temperature threshold of the capacitor, and at the same time, the increase of the radiator temperature of the power submodule compared to the average value of the radiator temperatures of all the power submodules on the bridge arm where the power submodule is located is greater than the set increase of the radiator temperature and the radiator temperature of the power submodule is greater than the first set value of the radiator temperature, it is determined that the capacitor of the power submodule is abnormal; The capacitor temperature setting increment is greater than or equal to 10°C, the capacitor first temperature threshold is greater than or equal to 50°C, the radiator temperature setting increment is greater than or equal to 10°C, and the radiator temperature first setting value is greater than or equal to 50°C.

4. The power submodule state detection method of the converter valve according to claim 2, characterized in that: Also includes: When the attenuation rate of the capacitance of the power submodule capacitor compared to the average capacitance of all power submodules on the bridge arm where the power submodule is located is greater than the set attenuation rate of the capacitor capacitance and the attenuation rate compared to the initial value of the capacitance of the power submodule is greater than the second attenuation rate, and at the same time, the change rate of the capacitor voltage of the power submodule compared to the rated value of the capacitor voltage is not within the set capacitor voltage change rate range, it is determined that the capacitor of the power submodule is faulty; The second attenuation rate is greater than or equal to 6%.

5. The power submodule state detection method of the converter valve according to claim 3, characterized in that: Also includes: When the increase in the temperature of the power submodule capacitor compared to the average value of the capacitor temperatures of all the power submodules on the bridge arm where the power submodule is located is greater than the set increase in the capacitor temperature and the temperature of the power submodule capacitor is greater than the second capacitor temperature threshold, and at the same time, the increase in the radiator temperature of the power submodule compared to the average value of the radiator temperatures of all the power submodules on the bridge arm where the power submodule is located is greater than the set increase in the radiator temperature and the radiator temperature of the power submodule is greater than the first set radiator temperature value, it is determined that the capacitor of the power submodule is faulty; The second temperature threshold of the capacitor is greater than or equal to 60°C.

6. The power submodule state detection method of a converter valve according to claim 3, characterized in that: Also includes: When any one of the on-state saturation voltage drop of the IGBT of the power submodule, the switching frequency of the IGBT, the junction temperature of the IGBT and the heat sink temperature meets the corresponding set conditions, the IGBT is determined to be abnormal; The setting condition corresponding to the on-state saturation voltage drop of the IGBT is that the growth rate of the average value of the on-state saturation voltage drops of all IGBTs on the bridge arm where the power submodule is located is greater than the set growth rate of the on-state saturation voltage drop of the IGBT; The setting condition corresponding to the switching frequency of the IGBT is greater than the setting value of the switching frequency of the IGBT; The setting condition corresponding to the junction temperature of the IGBT is that the junction temperature is greater than the set junction temperature and the increase in the junction temperature of all IGBTs on the bridge arm where the power submodule is located is greater than the set increase in the junction temperature; The setting condition corresponding to the radiator temperature is that the radiator temperature is greater than the second setting value of the radiator temperature, and the increase amount compared to the average value of the radiator temperature of all power sub-modules on the bridge arm where the power sub-module is located is greater than the set increase amount of the radiator temperature; The on-state saturation voltage drop of the IGBT is set to a growth rate greater than or equal to 20%, the switching frequency setting value of the IGBT is greater than 500 Hz, the junction temperature is set to be greater than or equal to 110°C, the setting increase amount of the junction temperature is greater than or equal to 10°C, and the second setting value of the heat sink temperature is greater than or equal to 70°C.

7. The method for detecting the state of a power submodule of a converter valve according to claim 1, characterized in that: Also includes: If the number of communication failures between the power submodule and the valve control device is greater than a set number, it is determined that the communication of the power submodule is abnormal.

8. A power submodule state detection system for a converter valve, comprising a processor, characterized in that: The processor is used to execute computer program instructions to implement the steps of the power submodule state detection method of the converter valve according to any one of claims 1 to 7.

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