Converter control method and device
By configuring dual current measurement points on the bridge arm and comparing the fault judgment results, the problem of converter valve control disorder caused by abnormal bridge arm current sampling was solved, thus achieving stable and reliable operation of the converter and accurate fault detection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-09
- Publication Date
- 2026-03-27
AI Technical Summary
In existing technologies, abnormal sampling of the arm current in a modular multilevel converter system may cause malfunctions in the converter valve control system, or even system shutdown, affecting the stable and reliable operation of DC power transmission.
Each bridge arm is equipped with a first current measuring point and a second current measuring point, and the sampled current is transmitted to the converter valve control system and protection system. By comparing the fault judgment results, the measuring point switching or system switching strategy is executed to ensure stable and reliable operation.
It enables real-time detection and processing of bridge arm current sampling faults, improves the stability and reliability of the converter, enhances the flexibility and availability of the system, and reduces the impact of single-point faults on the system.
Smart Images
Figure CN121749070A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of converter technology, and in particular to a control method and apparatus for a converter. Background Technology
[0002] Modular multilevel converter systems are widely used in flexible DC transmission projects, ultra-high voltage hybrid DC, flexible low-frequency transmission, reactive power compensation, AC / DC energy storage, and other DC power electronic system fields. The converter valve control and protection system serves as the link between the converter control and protection system and the converter valve equipment. It receives commands from the converter control and protection system, modulates them to obtain control commands for each submodule of each bridge arm, and simultaneously receives status information from each submodule, participating in the control of the entire converter valve.
[0003] The converter valve control and protection system requires the acquisition of current data from each bridge arm. The converter valve control system is used for circulating current control and submodule voltage equalization control, while the converter valve protection system is used for overcurrent protection and bridge arm imbalance protection. Abnormal bridge arm current sampling may cause malfunctions in the converter valve control system, or even cause the converter valve to lock up, resulting in system shutdown.
[0004] Currently, existing technologies typically configure one current measurement point for each converter valve arm, and the fault detection methods for arm current are inadequate. When a fault occurs in the current sampling of any of the six arms, it may cause a switchover of the DC transmission control system, and in severe cases, it may lead to abnormal control functions, affecting the stable and reliable operation of the DC transmission system. Therefore, there is an urgent need to provide a stable and reliable control scheme. Summary of the Invention
[0005] A control method and device for a converter are provided to ensure the stable and reliable operation of the converter.
[0006] Firstly, a control method for a converter is provided, the converter including a converter valve control system, a converter valve protection system, and multiple bridge arms; the method includes: A first current measuring point and a second current measuring point are respectively configured in each bridge arm; The first sampled current at the first current measuring point and the second sampled current at the second current measuring point are transmitted to the converter valve control system and the converter valve protection system. The first fault judgment result of the converter valve control system and the second fault judgment result of the converter valve protection system are determined based on the first sampling current, the second sampling current and the preset fault judgment conditions, respectively. The fault judgment result of the bridge arm is determined by comparing the first fault judgment result and the second fault judgment result. Based on the fault diagnosis results, the converter valve control system executes the measurement point switching strategy or the system switching strategy.
[0007] In some embodiments, the preset fault determination conditions include: In the converter valve protection system, the absolute value of the sampled current of the bridge arm is greater than the first current threshold and remains for a first time threshold. In the converter valve control system, the absolute value of the sampled current of the bridge arm is greater than the first current threshold and remains for a second time threshold.
[0008] In some embodiments, the preset fault determination conditions include: In the unlocked state of the converter valve, the current sampling value of the bridge arm in the converter valve protection system does not cross zero within the third time threshold, and the current sampling value of the bridge arm in the converter valve control system does not cross zero within the fourth time threshold.
[0009] In some embodiments, the preset fault determination conditions include: When the converter valve is unlocked and there is circulating current injection, the effective value of the current sampling of the bridge arm in the converter valve protection system is less than the second current threshold and lasts for a fifth time threshold, and the effective value of the sampling current of the bridge arm in the converter valve control system is less than the second current threshold and lasts for a sixth time threshold.
[0010] In some embodiments, the second current threshold is determined based on the minimum effective value of the sampled current of the bridge arm when the converter valve is unlocked and there is circulating current injection.
[0011] In some embodiments, the converter valve control system executes a measurement point switching strategy or a system switching strategy based on the sampling fault judgment result, including: If there are no abnormalities at the first and second current measuring points of the bridge arm, select the data of the target measuring point, which is any one of the current measuring points; If the data at the target measuring point is abnormal, the converter valve control system switches to another current measuring point to continue operation; If both the first and second current measuring points of the bridge arm are abnormal, the converter valve control system generates a corresponding fault and sends it to the upper-level control and protection system for the upper-level control and protection system to perform system switching or exit standby.
[0012] In some embodiments, the first current measuring point and the second current measuring point of the bridge arm are respectively configured on the DC side and AC side of the corresponding bridge arm.
[0013] In some embodiments, the converter valve control system includes a first control redundancy system and a second control redundancy system; the converter valve protection system includes a first protection redundancy system, a second protection redundancy system, and a third protection redundancy system; the method further includes: The first and second sampled currents of the bridge arm are transmitted to the first and second control redundancy systems. The first and second sampled currents of the bridge arm are transmitted to the first, second, and third protection redundancy systems.
[0014] In some embodiments, the method for determining a first fault determination result includes: The first control redundancy system and the second control redundancy system determine the first control redundancy fault result and the second control redundancy fault result respectively based on the first sampling current, the second sampling current and the preset fault judgment conditions. The methods for determining the result of the second fault diagnosis include: The first protection redundancy system, the second protection redundancy system, and the third protection redundancy system determine the first protection redundancy fault result, the second protection redundancy fault result, and the third protection redundancy fault result, respectively, based on the first sampling current, the second sampling current, and the preset fault judgment conditions. Based on the results of the first, second, and third protection redundancy faults, the second fault judgment result is finally determined by the two-out-of-three unit in the converter valve protection system.
[0015] In some embodiments, the control method for the converter further includes: When the first, second, and third protection redundancy systems are all fault-free, the second fault judgment result is determined by a two-out-of-three logic. If one of the first, second, and third protection redundancy systems is faulty, the remaining two fault-free protection redundancy systems use a two-out-of-one logic to determine the second fault judgment result. If two of the first, second, and third protection redundancy systems are faulty, the remaining fault-free protection redundancy systems use a one-out-one logic to determine the second fault judgment result. If the first, second, and third protection redundancy systems all fail, the converter valve control system will request a trip and will no longer make any judgments regarding abnormal arm current sampling data.
[0016] Secondly, embodiments of this application also provide a control device for a converter, the converter including a converter valve control system, a converter valve protection system, and multiple bridge arms; the device includes: The configuration module is used to configure the first current measuring point and the second current measuring point in each bridge arm respectively; The transmission module is used to transmit the first sampled current of the first current measuring point and the second sampled current of the second current measuring point to the converter valve control system and the converter valve protection system. The first determining module is used to determine the first fault judgment result of the converter valve control system based on the first sampling current, the second sampling current and the preset fault judgment conditions. The second determining module is used to determine the second fault judgment result of the converter valve protection system based on the first sampling current, the second sampling current and the preset fault judgment conditions. The third determining module is used to determine the current sampling fault judgment result of the bridge arm by comparing the first fault judgment result and the second fault judgment result; The execution module is used to execute the measurement point switching strategy or system switching strategy through the converter valve control system based on the sampling fault judgment result.
[0017] Beneficial Effects: This application provides a converter control method and apparatus. The converter control method includes: configuring a first current measuring point and a second current measuring point in each bridge arm; transmitting a first sampled current from the first current measuring point and a second sampled current from the second current measuring point to a converter valve control system and a converter valve protection system; determining a first fault judgment result of the converter valve control system and a second fault judgment result of the converter valve protection system based on the first sampled current, the second sampled current, and preset fault judgment conditions; determining the current sampling fault judgment result of the bridge arm by comparing the first fault judgment result and the second fault judgment result; and executing a measuring point switching strategy or a system switching strategy through the converter valve control system based on the sampling fault judgment result. The converter control method provided in this application detects and determines the fault judgment results of the converter valve control system and the converter valve protection system in real time, and determines whether to execute a measuring point switching strategy or a system switching strategy by comparing the two fault judgment results, thereby achieving converter fault detection and handling, and ensuring the stable and reliable operation of the converter. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.
[0020] Figure 1 This is a flowchart of a converter control method provided in the embodiments of this application; Figure 2 This is a schematic diagram of one arm of a modular multilevel converter and the current measurement point configuration provided in the embodiments of this application; Figure 3 This is a schematic diagram of the modular multilevel converter arm anomaly detection provided in the embodiments of this application; Figure 4 This is a schematic diagram showing the configuration and connection relationship of the upper-level control and protection system, the converter valve control system, and the converter valve protection system provided in the embodiments of this application; Figure 5 This is a schematic diagram of the switching process of the current measurement point of the modular multilevel converter bridge arm provided in the embodiments of this application; Figure 6 This is a schematic diagram of the overall flow of a converter control method provided in the embodiments of this application; Figure 7 This is a schematic diagram of the control device for a converter provided in the embodiments of this application. Detailed Implementation
[0021] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.
[0022] In the embodiments of this application, "at least one" refers to one or more; "multiple" refers to two or more. In the description of this application, the terms "first," "second," "third," etc., are used only for the purpose of distinguishing descriptions and should not be construed as indicating or implying relative importance, nor should they be construed as indicating or implying order.
[0023] References such as “one embodiment” or “some embodiments” as described in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the terms “comprising,” “including,” “having,” and variations thereof, as used in this specification, mean “including, but not limited to,” unless otherwise specifically emphasized.
[0024] It should be noted that in the embodiments of this application, "and / or" describes the relationship between associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. In addition, the character " / ", unless otherwise specified, generally indicates that the associated objects before and after it are in an "or" relationship.
[0025] It should be noted that in the embodiments of this application, "connection" can be understood as electrical connection. The connection between two electrical components can be a direct or indirect connection between the two electrical components. For example, the connection between A and B can be a direct connection between A and B, or an indirect connection between A and B through one or more other electrical components.
[0026] It should be noted that the converters provided in this application include modular multilevel converters, etc. For example, the control of a modular multilevel converter will be used as an example in this application embodiment, and will not be repeated below.
[0027] Figure 1 This is a flowchart illustrating a converter control method provided in an embodiment of this application. This application provides a converter control method; please refer to [link to relevant documentation]. Figure 1 The control method for this converter includes the following steps: Step 110: Configure a first current measuring point and a second current measuring point in each bridge arm.
[0028] The converter is a modular multilevel converter. It includes a converter valve control system, a converter valve protection system, and multiple bridge arms. For example, a modular multilevel converter has six bridge arms, each equipped with a first current measuring point and a second current measuring point. The converter valve control system is used for circulating current control and submodule voltage equalization control, while the converter valve protection system is used for overcurrent protection and bridge arm imbalance protection.
[0029] Specifically, the first and second sampling currents of the corresponding bridge arm can be detected and obtained through the first and second current measuring points. By configuring the first and second current measuring points for each bridge arm, the flexibility of system control can be increased and the scope of system protection can be expanded.
[0030] The first sampling current at the first current measuring point and the second sampling current at the second current measuring point can be obtained by current detection elements, such as current transformers.
[0031] Figure 2 This is a schematic diagram of one arm of a modular multilevel converter and the current measurement point configuration provided in an embodiment of this application. In some embodiments, see [reference needed]. Figure 2 The first and second current measuring points of the bridge arm are respectively configured on the DC side and AC side of the corresponding bridge arm.
[0032] See Figure 2 One arm of the converter is formed by connecting submodules 1, 2, 3, ..., N in series. The positions of the first and second current measuring points of each arm correspond to the DC side and AC side of the arm, respectively.
[0033] Step 120: Transmit the first sampling current of the first current measuring point and the second sampling current of the second current measuring point to the converter valve control system and the converter valve protection system.
[0034] Specifically, the bridge arm current measurement point configuration method is as follows: each bridge arm is configured with a first current measurement point and a second current measurement point. The first and second sampled currents of the corresponding bridge arm are obtained through the first and second current measurement points of each bridge arm, and the first and second sampled currents of each bridge arm are simultaneously transmitted to the converter valve control system and the converter valve protection system.
[0035] In some embodiments, the converter valve control system includes a first control redundancy system A1 and a second control redundancy system B1; the converter valve protection system includes a first protection redundancy system A2, a second protection redundancy system B2 and a third protection redundancy system C; the control method of the converter further includes: transmitting a first sampling current and a second sampling current of the bridge arm to the first control redundancy system A1 and the second control redundancy system B1; transmitting the first sampling current and the second sampling current of the bridge arm to the first protection redundancy system A2, the second protection redundancy system B2 and the third protection redundancy system C.
[0036] Specifically, the bridge arm current measurement point configuration method also includes: the sampling data (including the first sampling current and the second sampling current) of the first current measurement point and the second current measurement point of the bridge arm are simultaneously transmitted to the first control redundancy system A1 and the second control redundancy system B1 of the converter valve control system; the sampling data (including the first sampling current and the second sampling current) of the first current measurement point and the second current measurement point of the bridge arm are simultaneously transmitted to the first protection redundancy system A2, the second protection redundancy system B2 and the third protection redundancy system C of the converter valve protection system.
[0037] Step 130: Determine the first fault judgment result of the converter valve control system and the second fault judgment result of the converter valve protection system based on the first sampling current, the second sampling current and the preset fault judgment conditions.
[0038] Specifically, the bridge arm current fault detection method includes the following steps: Step 1: The converter valve control system and the converter valve protection system respectively acquire the first sampled current data of the first current measuring point and the second sampled current data of the second current measuring point of the bridge arm.
[0039] Step 2: Based on the current sampling data from the bridge arm current measuring points, determine whether the bridge arm current meets the preset fault judgment conditions.
[0040] Step 3: When the current sampling data of the bridge arm current measuring point meets the preset fault judgment conditions, it is determined that the current sampling of the corresponding bridge arm current measuring point is abnormal.
[0041] In some embodiments, the preset fault judgment conditions include: the absolute value of the sampled current of the bridge arm in the converter valve protection system is greater than a first current threshold and lasts for a first time threshold; and the absolute value of the sampled current of the bridge arm in the converter valve control system is greater than a first current threshold and lasts for a second time threshold.
[0042] The specific value of the first current threshold can be set according to the actual situation, and no specific limit is made here.
[0043] The setting of the first and second time thresholds needs to take into account the communication cycle and delay between the converter valve protection system and the converter valve control system.
[0044] Specifically, the fault judgment conditions for the bridge arm current include Condition 1, which is: for the sampled current data of the same current measuring point of the bridge arm current, a first current threshold is set, a first time threshold is set for the converter valve protection system, and a second time threshold is set for the converter valve control system. The preset fault judgment conditions are: the absolute value of the sampled current of the bridge arm in the converter valve protection system is greater than the first current threshold and remains above the first time threshold; the absolute value of the sampled current of the bridge arm in the converter valve control system is greater than the first current threshold and remains above the second time threshold. For example, if the absolute value of the sampled current of the bridge arm in the converter valve protection system does not meet the requirement of being greater than the first current threshold and remaining above the first time threshold, it indicates that the current of that bridge arm in the converter valve protection system is normal, and the second fault judgment result is invalid. Similarly, if the absolute value of the sampled current of the bridge arm in the converter valve control system is greater than the first current threshold and remains above the second time threshold, it indicates that the first fault judgment result of the current of that bridge arm in the converter valve control system is valid; if the first fault judgment result of the converter valve control system is valid and the second fault judgment result of the converter valve protection system is invalid, then the bridge arm current sampling in the converter valve control system is determined to be abnormal.
[0045] In some embodiments, the preset fault judgment conditions include: when the converter valve is unlocked, the instantaneous current value of the bridge arm in the converter valve protection system does not cross zero within a third time threshold, and the instantaneous current value of the bridge arm in the converter valve control system does not cross zero within a fourth time threshold.
[0046] The setting of the third and fourth time thresholds needs to take into account the communication cycle and delay between the converter valve protection system and the converter valve control system.
[0047] Specifically, the fault judgment conditions for the bridge arm current include condition two: In the unlocked state of the converter valve, for the current sampling data of the same current measuring point of the bridge arm current, the converter valve protection system sets a third time threshold, and the converter valve control system sets a fourth time threshold. The preset fault judgment condition is: In the unlocked state of the converter valve, the instantaneous value of the bridge arm current sampled in the converter valve protection system does not cross zero within the third time threshold, and the instantaneous value of the bridge arm current sampled in the converter valve control system does not cross zero within the fourth time threshold. For example, if the sampled current value of the bridge arm in the converter valve protection system does not meet the requirement that the instantaneous value of the bridge arm current does not cross zero within the third time threshold, it indicates that the current of that bridge arm in the converter valve protection system is normal. If the sampled current value of the bridge arm in the converter valve control system does not cross zero within the fourth time threshold, it indicates that the current of that bridge arm in the converter valve control system is abnormal.
[0048] In some embodiments, the preset fault judgment conditions include: when the converter valve is in the unlocked state and there is circulating current injection, the effective value of the current sampling of the bridge arm in the converter valve protection system is less than the second current threshold and lasts for a fifth time threshold, and the effective value of the sampling current of the bridge arm in the converter valve control system is less than the second current threshold and lasts for a sixth time threshold.
[0049] The setting of the fifth and sixth time thresholds needs to take into account the communication cycle and delay between the converter valve protection system and the converter valve control system.
[0050] Specifically, the fault judgment conditions for the bridge arm current include condition three: Under the condition of the converter valve being unlocked and with circulating current injection, a second current threshold is set for the sampled current data at the same current measuring point of the bridge arm current; a fifth time threshold is set for the converter valve protection system; and a sixth time threshold is set for the converter valve control system. The preset fault judgment conditions are: under the condition of the converter valve being unlocked and with circulating current injection, the effective value of the sampled current of the bridge arm in the converter valve protection system is less than the second current threshold and remains below the fifth time threshold; and the effective value of the sampled current of the bridge arm in the converter valve control system is less than the second current threshold and remains below the sixth time threshold. For example, if the effective value of the sampled current of the bridge arm in the converter valve protection system does not meet the requirement of being less than the second current threshold and remaining below the fifth time threshold, it indicates that the current of that bridge arm in the converter valve protection system is normal. If the effective value of the sampled current of the bridge arm in the converter valve control system is less than the second current threshold and remains below the sixth time threshold, it indicates that the current of that bridge arm in the converter valve control system is abnormal.
[0051] In some embodiments, the second current threshold is determined based on the minimum effective value of the sampled current of the bridge arm when the converter valve is unlocked and there is circulating current injection.
[0052] In some embodiments, the method for determining a first fault judgment result includes: a first control redundancy system and a second control redundancy system determining a first control redundancy fault result and a second control redundancy fault result respectively based on a first sampling current, a second sampling current and preset fault judgment conditions.
[0053] The method for determining the second fault judgment result includes: the first protection redundancy system, the second protection redundancy system, and the third protection redundancy system respectively determine the first protection redundancy fault result, the second protection redundancy fault result, and the third protection redundancy fault result based on the first sampling current, the second sampling current, and the preset fault judgment conditions; based on the first protection redundancy fault result, the second protection redundancy fault result, and the third protection redundancy fault result, the two-out-of-three unit in the converter valve protection system finally determines the second fault judgment result.
[0054] Among them, the results of the first control redundancy fault, the second control redundancy fault, the first protection redundancy fault, the second protection redundancy fault, and the third protection redundancy fault all include normal and abnormal judgment results.
[0055] Specifically, the first control redundancy system A1 and the second control redundancy system B1 of the converter valve control system determine whether the bridge arm current meets the preset fault judgment conditions. For example, the first control redundancy system A1 determines the first control redundancy fault result based on the first sampled current, the second sampled current, and the preset fault judgment conditions. The second control redundancy system B1 determines the second control redundancy fault result based on the first sampled current, the second sampled current, and the preset fault judgment conditions.
[0056] The converter valve protection system's first redundancy system A2, second redundancy system B2, and third redundancy system C each determine whether the bridge arm current meets preset fault judgment conditions. For example, the first redundancy system A2 determines the first redundancy fault result based on the first sampled current, the second sampled current, and the preset fault judgment conditions. The second redundancy system B2 determines the second redundancy fault result based on the first sampled current, the second sampled current, and the preset fault judgment conditions. The third redundancy system C determines the third redundancy fault result based on the first sampled current, the second sampled current, and the preset fault judgment conditions.
[0057] In some embodiments, the control method of the converter further includes: when the first, second, and third protection redundant systems are all fault-free, a two-out-of-three logic is used to determine the second fault judgment result; when one of the first, second, and third protection redundant systems is faulty, the remaining two fault-free protection redundant systems are used to determine the second fault judgment result using a one-out-of-two logic; when two of the first, second, and third protection redundant systems are faulty, the remaining fault-free protection redundant systems are used to determine the second fault judgment result using a one-out-of-one logic; when all three protection redundant systems are faulty, the converter valve control system will request a trip and will no longer perform related judgments on abnormal arm current sampling data.
[0058] The meaning of "no fault in the protection redundancy system" is that its judgment result can participate in the 2-out-of-3 logic. For example, assuming the first current threshold is 1000A, if the sampled value of the first protection redundancy system is 1100A, then the first protection redundancy fault judgment result is valid; if the sampled value of the second protection redundancy system is 1100A, then the second protection redundancy fault judgment result is valid; at this time, regardless of whether the sampled value of the third protection redundancy system is higher than 1000A, the 2-out-of-3 unit will determine that the second fault judgment result of the valve protection system is valid. That is, if the first and second protection redundancy systems determine that there is an overcurrent, the judgment result of the entire converter valve protection system is an overcurrent.
[0059] If the first redundant protection system itself is faulty, its judgment result cannot participate in the 2-out-of-3 logic. For example, assuming the first current threshold is 1000A, if the sampled value of the second redundant protection system is 1100A, then the fault result of the second redundant protection system is valid. In this case, regardless of whether the sampled value of the third redundant protection system is higher than 1000A, the 2-out-of-3 unit will determine that the second fault judgment result of the converter valve protection system is valid. That is, if the first redundant protection system is faulty and the second redundant protection system determines that there is an overcurrent, the judgment result of the entire converter valve protection system will be an overcurrent. The fault of a single system can be one of three cases: a fault in the first redundant protection system, a fault in the second redundant protection system, or a fault in the third redundant protection system.
[0060] If the first and second redundant protection systems themselves are faulty, their judgment results cannot participate in the 2-out-of-3 logic. For example, assuming the first current threshold is 1000A, if the sampled value of the third redundant protection system is 1100A, then the fault result of the third redundant protection system is valid; in this case, the 2-out-of-3 unit determines that the second fault judgment result of the converter valve protection system is valid. That is, if the first and second redundant protection systems are faulty, and the third redundant protection system judges an overcurrent, the judgment result of the entire converter valve protection system is an overcurrent. The situations where the two systems themselves are faulty can be categorized into three cases: both the first and second redundant protection systems are faulty; both the first and third redundant protection systems are faulty; and both the second and third redundant protection systems are faulty.
[0061] Figure 3 This is a schematic diagram of the modular multilevel converter arm anomaly detection provided in an embodiment of this application. (See also...) Figure 3 The converter valve control system includes a first control redundancy system A1 and a second control redundancy system B1; the converter valve protection system includes a first protection redundancy system A2, a second protection redundancy system B2 and a third protection redundancy system C.
[0062] Specifically, the sampled current data from the first and second current measuring points of the bridge arm are simultaneously transmitted to the first control redundancy system A1 and the second control redundancy system B1 of the converter valve control system; the sampled current data from the first and second current measuring points of the bridge arm are simultaneously transmitted to the first protection redundancy system A2, the second protection redundancy system B2, and the third protection redundancy system C of the converter valve protection system. The first control redundancy system A1 and the second control redundancy system B1 of the converter valve control system respectively determine whether the bridge arm current meets the preset fault judgment conditions; the first protection redundancy system A2, the second protection redundancy system B2, and the third protection redundancy system C of the converter valve protection system respectively determine whether the bridge arm current meets the preset fault judgment conditions. When the converter valve protection system finally determines whether the bridge arm current meets the preset fault judgment conditions, it considers the judgment results of the three protection systems (first protection redundancy system A2, second protection redundancy system B2, and third protection redundancy system C) comprehensively, specifically as follows: (1) When all three protection systems are fault-free, the "two out of three" logic is adopted.
[0063] (2) When one of the three protection systems is faulty, the "two-out-of-one" logic is adopted.
[0064] (3) When two of the three protection systems are faulty, the "one-out-of-one" logic is adopted.
[0065] (4) When all three protection systems fail, the judgment of whether the bridge arm current of the converter valve control system is abnormal will no longer be performed.
[0066] The converter valve control system obtains the final abnormal signal of the current measurement point (i.e., the second fault judgment result of the converter valve protection system) based on its own fault judgment condition judgment result and the two-out-of-three judgment result of the fault judgment condition of the converter valve protection system.
[0067] Step 140: By comparing the first fault judgment result and the second fault judgment result, determine the current sampling fault judgment result of the bridge arm.
[0068] Specifically, the fault judgment results of the converter valve control system and the converter valve protection system are compared. When the current measurement point data of the bridge arm meets the preset fault judgment conditions, the sampling of the corresponding bridge arm current measurement point is determined to be abnormal. For example, if the first fault judgment result of a certain measurement point of a certain bridge arm is valid (true / 1) in the converter valve control system, and the second fault judgment result of the converter valve protection system is invalid (false / 0), then the current sampling of that measurement point of that bridge arm in the converter valve control system is determined to be abnormal. For example, assuming the first current threshold is 1000A, if the sampling value of the converter valve control system is 2000A and the sampling value of the converter valve protection system is 900A, then the first fault judgment result of the converter valve control system is valid (true / 1), and the second fault judgment result of the converter valve protection system is invalid (false / 0). That is, the converter valve control system judges that there is an overcurrent, while the converter valve protection system judges that there is no overcurrent. At this time, the sampling data of the converter valve control system is considered abnormal.
[0069] It should be noted that if the second fault judgment result in the converter valve protection system is valid, the converter valve protection system will take corresponding actions, such as system tripping, without needing to perform related logic in the control system. In other words, the core idea of this application is that, for the same quantity sampling, if the converter valve protection system considers it without problem, but the converter valve control system considers it with problem, then the sampling of the control system is determined to be problematic, because the result of the converter valve protection system is determined by a two-out-of-three logic, which is more reliable in comparison.
[0070] Step 150: Based on the sampling fault judgment results, execute the measurement point switching strategy or system switching strategy through the converter valve control system.
[0071] The measurement point switching strategy refers to switching between the first current measurement point and the second current measurement point. For example, if the current at the first current measurement point of a certain bridge arm is found to be abnormal, while the current at another current measurement point (such as the second current measurement point) of the corresponding bridge arm is normal, the current measurement point is switched from the first current measurement point to the second current measurement point. The system switching strategy refers to performing a system switch when both the current at the first current measurement point and the second current measurement point of a bridge arm are abnormal. For example, when both the current at the first current measurement point and the second current measurement point of the bridge arm of the first control redundancy system A1 of the converter valve control system are abnormal, the control redundancy system is switched from the first control redundancy system A1 to the second control redundancy system B1.
[0072] It is understood that the converter control method provided in this application embodiment detects and determines the fault judgment results of the converter valve control system and the converter valve protection system in real time, and determines whether to execute the measurement point switching strategy or the system switching strategy by comparing the fault judgment results of the two, thereby realizing the fault detection and handling of the converter and ensuring the stable and reliable operation of the converter.
[0073] In some embodiments, the converter valve control system executes a measurement point switching strategy or a system switching strategy based on the sampling fault judgment result, including: if neither the first current measurement point nor the second current measurement point of the bridge arm is abnormal, selecting the data of a target measurement point, wherein the target measurement point is any one of the current measurement points; if the data of the target measurement point is abnormal, the converter valve control system switches to another current measurement point to continue operation; if both the first current measurement point and the second current measurement point of the bridge arm are abnormal, the converter valve control system requests the upper-level control and protection system to perform system switching.
[0074] Figure 4 This is a schematic diagram showing the configuration and connection relationship of the upper-level control and protection system, the converter valve control system, and the converter valve protection system provided in the embodiments of this application.
[0075] Among them, the upper-level control and protection system refers to the converter or DC control and protection system, which is responsible for controlling the entire converter or the entire DC transmission system and providing necessary control commands to the converter valve control system.
[0076] The converter valve control system is responsible for controlling the converter valves and is connected one-to-one with the upper-level control and protection system. Its on-duty / standby status follows that of the upper-level control and protection system. When a fault occurs in the converter valve control system, it sends relevant fault information to the upper-level control and protection system, which then performs a system switchover or exits standby operation. Specifically, when the converter valve control system requests a switchover, if the corresponding upper-level control and protection system is on-duty, a system switchover operation is performed; if the corresponding upper-level control and protection system is in standby mode, a system exit standby operation is performed.
[0077] The converter valve protection system is responsible for the protection of the converter valve, including three redundant protection systems. Each redundant protection system makes independent judgments, and the final decision on the fault judgment results of the three redundant protection systems is made by the protection three-out-of-two unit.
[0078] Specifically, if neither the first nor the second current measuring point of the bridge arm is abnormal, the data from one of the current measuring points is selected first; if the data from the selected current measuring point is abnormal, the converter valve control system switches to the other current measuring point to continue operation; if both the first and the second current measuring points of the bridge arm are abnormal, the converter valve control system requests the upper-level control and protection system to switch the system.
[0079] Figure 5 This is a schematic diagram of the switching process for the current measurement points of the modular multilevel converter bridge arm provided in this embodiment of the application. For example, see [link to relevant documentation]. Figure 5 The converter valve control system prioritizes the sampling current data from the first current measuring point of the bridge arm. If there is no abnormality at the first current measuring point, the converter valve control system uses the current data from the first current measuring point for control. If an abnormality occurs at the first current measuring point, and there is no abnormality at the second current measuring point, the converter valve control system uses the data from the second current measuring point for control; if an abnormality occurs at the second current measuring point, the converter valve control system requests system switching.
[0080] In another embodiment, if the converter valve control system preferentially selects the current data from the second current measuring point of the bridge arm, the measuring point switching logic is... Figure 5 Similarly, I will not go into details here.
[0081] Figure 6 This is a schematic flowchart illustrating the overall process of a converter control method provided in an embodiment of this application. For an example, please refer to [link to example]. Figure 6The overall flow of the converter control method is as follows: Step S201 is the arm current measurement point configuration module, where the positions of the first and second current measurement points on the arm can correspond to the DC and AC sides of the arm, respectively. Step S202 is the arm current transmission module, where the sampled data from the first and second current measurement points on the arm are simultaneously transmitted to the converter valve control system and the converter valve protection system. Step S203 is the fault judgment condition judgment module, where the converter valve control system and the converter valve protection system determine whether the arm current meets the preset fault judgment conditions based on the data from the two measurement points. Step S204 is the measurement point data anomaly judgment module, where the converter valve control system, based on its own fault judgment condition judgment result and the fault judgment condition two-out-of-three judgment result from the converter valve protection system, obtains the final current measurement point anomaly signal. Step S205 is the switching logic module. When neither the first current measuring point nor the second current measuring point of the bridge arm is abnormal, the data of one of the measuring points is selected first. When the selected current measuring point is abnormal, the converter valve control system switches to the other measuring point to continue operation. When both the first current measuring point and the second current measuring point of the bridge arm are abnormal, the converter valve control system requests the upper-level control and protection system to perform system switching.
[0082] In summary, the embodiments of this application, by configuring current measuring points on both the DC and AC sides of each arm of the converter valve, can increase the flexibility of system control and expand the scope of system protection. The current measuring point data on both the DC and AC sides of the arm are verified separately. By comparing the differences between the control and protection measuring point data, fault detection of the arm current measuring point data is achieved. Based on the fault conditions of the DC and AC side current measuring points, corresponding switching logic is established: for a given arm, when both measuring points are fault-free, the converter valve control system preferentially selects the data from one of the measuring points; when the preferentially selected measuring point fails, the converter valve control system switches to the other measuring point to continue operation; when both measuring points fail, the converter valve control system requests the upper-level control and protection system to perform system switching.
[0083] Furthermore, compared with related technologies, this application has the following advantages: First, by configuring two current measuring points on the bridge arm, the flexibility of control is increased.
[0084] Secondly, if an anomaly occurs at a single measuring point, only the measuring point data is switched, which improves the reliability of the system.
[0085] Third, the control system only requests a system switch when two measuring points on the same bridge arm are abnormal at the same time, which improves the availability of the system.
[0086] Fourth, the converter valve control system and the converter valve protection system independently judge and verify, which improves the accuracy of fault detection.
[0087] Figure 7This is a schematic block diagram of a converter control device provided in an embodiment of this application. This application also provides a converter control device; please refer to [link / reference]. Figure 7 The converter control device 100 includes: a configuration module 101 for configuring a first current measuring point and a second current measuring point in each bridge arm; a transmission module 102 for transmitting the first sampled current of the first current measuring point and the second sampled current of the second current measuring point to the converter valve control system and the converter valve protection system; a first determination module 103 for determining a first fault judgment result of the converter valve control system based on the first sampled current, the second sampled current, and preset fault judgment conditions; a second determination module 104 for determining a second fault judgment result of the converter valve protection system based on the first sampled current, the second sampled current, and preset fault judgment conditions; a third determination module 105 for determining the current sampling fault judgment result of the bridge arm by comparing the first fault judgment result and the second fault judgment result; and an execution module 106 for executing a measuring point switching strategy or a system switching strategy through the converter valve control system based on the sampling fault judgment result.
[0088] The technical solution of this application embodiment provides a converter control device, which detects and determines the fault judgment results of the converter valve control system and the converter valve protection system in real time, and determines whether to execute the measurement point switching strategy or the system switching strategy by comparing the two fault judgment results, thereby realizing the fault detection and handling of the converter and ensuring the stable and reliable operation of the converter.
[0089] In some embodiments, the preset fault determination conditions include: In the converter valve protection system, the absolute value of the sampled current of the bridge arm is greater than the first current threshold and remains for a first time threshold. In the converter valve control system, the absolute value of the sampled current of the bridge arm is greater than the first current threshold and remains for a second time threshold.
[0090] In some embodiments, the preset fault determination conditions include: In the unlocked state of the converter valve, the current sampling value of the bridge arm in the converter valve protection system does not cross zero within the third time threshold, and the current sampling value of the bridge arm in the converter valve control system does not cross zero within the fourth time threshold.
[0091] In some embodiments, the preset fault determination conditions include: When the converter valve is unlocked and there is circulating current injection, the effective value of the current sampling of the bridge arm in the converter valve protection system is less than the second current threshold and lasts for a fifth time threshold, and the effective value of the sampling current of the bridge arm in the converter valve control system is less than the second current threshold and lasts for a sixth time threshold.
[0092] In some embodiments, the second current threshold is determined based on the minimum effective value of the sampled current of the bridge arm when the converter valve is unlocked and there is circulating current injection.
[0093] In some embodiments, the execution module 106 is further configured to: If neither the first current measuring point nor the second current measuring point of the bridge arm is abnormal, the data from one of the current measuring points shall be selected first. If the data from the preferred current measuring point is abnormal, the converter valve control system switches to another current measuring point to continue operation. If both the first and second current measuring points of the bridge arm are abnormal, the converter valve control system generates a corresponding fault and sends it to the upper-level control and protection system for the upper-level control and protection system to perform system switching or exit standby.
[0094] In some embodiments, the first current measuring point and the second current measuring point of the bridge arm are respectively configured on the DC side and AC side of the corresponding bridge arm.
[0095] In some embodiments, the converter valve control system includes a first control redundancy system and a second control redundancy system; the converter valve protection system includes a first protection redundancy system, a second protection redundancy system and a third protection redundancy system; the converter control device 100 further includes: a first transmission unit, used to transmit the first sampling current and the second sampling current of the bridge arm to the first control redundancy system and the second control redundancy system; The second transmission unit is used to transmit the first and second sampled currents of the bridge arm to the first protection redundancy system, the second protection redundancy system and the third protection redundancy system.
[0096] In some embodiments, the first determining module 103 is further configured to: The first control redundancy system and the second control redundancy system determine the first control redundancy fault result and the second control redundancy fault result respectively based on the first sampling current, the second sampling current and the preset fault judgment conditions. The second determining module 104 is also used for: The first protection redundancy system, the second protection redundancy system, and the third protection redundancy system determine the first protection redundancy fault result, the second protection redundancy fault result, and the third protection redundancy fault result respectively based on the first sampling current, the second sampling current, and the preset fault judgment conditions. Based on the results of the first, second, and third protection redundancy faults, the second fault judgment result is finally determined by the two-out-of-three unit in the converter valve protection system.
[0097] In some embodiments, the control device 100 of the converter further includes a fourth determining module, which is further configured to: When the first, second, and third protection redundancy systems are all fault-free, the second fault judgment result is determined by a two-out-of-three logic. If one of the first, second, and third protection redundancy systems is faulty, the remaining two fault-free protection redundancy systems use a two-out-of-one logic to determine the second fault judgment result. If two of the first, second, and third protection redundancy systems are faulty, the remaining fault-free protection redundancy systems use a one-out-one logic to determine the second fault judgment result. If the first, second, and third protection redundancy systems all fail, the converter valve control system will request a trip and will no longer make any judgments regarding abnormal arm current sampling data.
[0098] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0099] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Although this application has disclosed preferred embodiments as above, it is not intended to limit this application. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the technical solution of this application. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.
Claims
1. A control method for a converter, characterized in that, The converter includes a converter valve control system, a converter valve protection system, and multiple bridge arms; the method includes: A first current measuring point and a second current measuring point are respectively configured in each of the bridge arms; The first sampled current of the first current measuring point and the second sampled current of the second current measuring point are transmitted to the converter valve control system and the converter valve protection system; The first fault judgment result of the converter valve control system and the second fault judgment result of the converter valve protection system are determined based on the first sampling current, the second sampling current and the preset fault judgment conditions, respectively. The current sampling fault judgment result of the bridge arm is determined by comparing the first fault judgment result and the second fault judgment result. Based on the sampling fault judgment result, the converter valve control system executes the measurement point switching strategy or the system switching strategy.
2. The method according to claim 1, characterized in that, The preset fault judgment conditions include: In the converter valve protection system, the absolute value of the sampled current of the bridge arm is greater than a first current threshold and remains for a first time threshold. In the converter valve control system, the absolute value of the sampled current of the bridge arm is greater than the first current threshold and remains for a second time threshold.
3. The method according to claim 1, characterized in that, The preset fault judgment conditions include: In the unlocked state of the converter valve, if the current sampling value of the bridge arm in the converter valve protection system does not cross zero within the third time threshold, and if the current sampling value of the bridge arm in the converter valve control system does not cross zero within the fourth time threshold, then the current sampling value of the bridge arm in the converter valve control system is not zero.
4. The method according to claim 1, characterized in that, The preset fault judgment conditions include: When the converter valve is unlocked and there is circulating current injection, the effective value of the current sampling of the bridge arm in the converter valve protection system is less than the second current threshold and lasts for a fifth time threshold, and the effective value of the sampling current of the bridge arm in the converter valve control system is less than the second current threshold and lasts for a sixth time threshold.
5. The method according to claim 4, characterized in that, The second current threshold is determined based on the minimum effective value of the sampled current of the bridge arm when the converter valve is unlocked and there is circulating current injection.
6. The method according to claim 1, characterized in that, The converter valve control system executes a measurement point switching strategy or a system switching strategy based on the sampled fault judgment result, including: If neither the first current measuring point nor the second current measuring point of the bridge arm is abnormal, the data of the target measuring point is selected, and the target measuring point is any one of the current measuring points; If the data at the target measuring point is abnormal, the converter valve control system switches to another current measuring point to continue operation. If both the first current measuring point and the second current measuring point of the bridge arm are abnormal, the converter valve control system generates a corresponding fault and sends it to the upper-level control and protection system for the upper-level control and protection system to perform system switching or exit standby.
7. The method according to claim 1, characterized in that, The first current measuring point and the second current measuring point of the bridge arm are respectively configured on the DC side and AC side of the corresponding bridge arm.
8. The method according to claim 1, characterized in that, The converter valve control system includes a first control redundancy system and a second control redundancy system; the converter valve protection system includes a first protection redundancy system, a second protection redundancy system, and a third protection redundancy system; the method further includes: The first sampled current and the second sampled current of the bridge arm are transmitted to the first control redundancy system and the second control redundancy system; The first and second sampled currents of the bridge arm are transmitted to the first protection redundancy system, the second protection redundancy system, and the third protection redundancy system.
9. The method according to claim 8, characterized in that, The method for determining the first fault determination result includes: The first control redundancy system and the second control redundancy system determine the first control redundancy fault result and the second control redundancy fault result respectively based on the first sampling current, the second sampling current and the preset fault judgment condition; The method for determining the second fault judgment result includes: The first protection redundancy system, the second protection redundancy system, and the third protection redundancy system respectively determine the first protection redundancy fault result, the second protection redundancy fault result, and the third protection redundancy fault result based on the first sampling current, the second sampling current, and the preset fault judgment condition; Based on the first protection redundancy fault result, the second protection redundancy fault result, and the third protection redundancy fault result, the second fault judgment result is finally determined by the two-out-of-three unit in the converter valve protection system.
10. The method according to claim 1, characterized in that, The method further includes: When the first protection redundancy system, the second protection redundancy system and the third protection redundancy system are all fault-free, the second fault judgment result is determined by a 2-out-of-3 logic. If one of the first, second, and third protection redundancy systems is faulty, the remaining two fault-free protection redundancy systems use a two-out-of-one logic to determine the second fault judgment result. If two of the first, second, and third protection redundancy systems are faulty, the remaining fault-free protection redundancy systems use a one-out-one logic to determine the second fault judgment result. If the first protection redundancy system, the second protection redundancy system, and the third protection redundancy system all fail, the converter valve control system will request a trip and will no longer make any judgments related to abnormal arm current sampling data.
11. A control device for a converter, characterized in that, The converter includes a converter valve control system, a converter valve protection system, and multiple bridge arms; the device includes: The configuration module is used to configure a first current measuring point and a second current measuring point in each of the bridge arms respectively; The transmission module is used to transmit the first sampled current of the first current measuring point and the second sampled current of the second current measuring point to the converter valve control system and the converter valve protection system; The first determining module is used to determine the first fault judgment result of the converter valve control system based on the first sampling current, the second sampling current and the preset fault judgment conditions. The second determining module is used to determine the second fault judgment result of the converter valve protection system based on the first sampling current, the second sampling current and the preset fault judgment condition. The third determining module is used to determine the current sampling fault judgment result of the bridge arm by comparing the first fault judgment result and the second fault judgment result; The execution module is used to execute the measurement point switching strategy or the system switching strategy through the converter valve control system based on the sampling fault judgment result.