A flexible direct-current converter valve protection method, device, system and storage medium

Abstract

The application discloses a flexible direct-current converter valve protection method, device, system and storage medium, and the method comprises the following steps: acquiring the collector-emitter voltage of each IGBT in the current control period converter valve; comparing the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control period; and determining the converter valve bridge arm to be locked according to the relationship between the code value and the determination threshold. The flexible direct-current converter valve protection method provided in the embodiment of the application has a larger sampling delay of the bridge arm current sensor, the protection method does not depend on the traditional bridge arm current sensor, can more accurately and quickly acquire the overcurrent state of the flexible direct-current converter valve, take corresponding protection measures, and improves the reliability of the converter valve protection.

Description

Technical Field

[0001] This invention relates to the field of flexible DC transmission technology, specifically to a method, device, system, and storage medium for protecting a flexible DC converter valve. Background Technology

[0002] In high-voltage flexible direct current (HVDC) transmission systems, converter valves, composed of IGBTs as basic components, are responsible for converting between DC and AC signals and are the core equipment of the entire system. Domestic flexible HVDC projects all adopt the Modular Multilevel Converter (MMC) technology for their converter valves. Their structural characteristics result in low DC system damping and a high fault current rise rate during system operation. Therefore, real-time monitoring and rapid protection of the flexible HVDC converter valve's arm current are necessary.

[0003] Currently, current transformers (CTs) located at the bridge arm reactor positions are used in engineering projects to detect the bridge arm current of the converter valve. Therefore, related overcurrent protection methods can only be configured based on the bridge arm current detected by the CT, resulting in a limited monitoring method. Furthermore, due to the limitations of the CT's own device performance, the sampling delay of the bridge arm current is relatively large, preventing the flexible DC system from being configured with a high overcurrent protection threshold and affecting the system's fault ride-through capability. In addition, when the current detection data transmitted by the CT is inaccurate, the lack of effective monitoring methods can easily lead to control instability in the flexible DC system and even equipment damage. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method, apparatus, system and storage medium for protecting a flexible DC converter valve, in order to solve the technical problem that the detection of converter valve arm current using CT is heavily dependent on the CT device and has poor reliability.

[0005] The technical solution proposed in this invention is as follows:

[0006] The first aspect of this invention provides a flexible DC converter valve protection method, comprising: acquiring the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; comparing the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT during the current control cycle; and determining the blocked converter valve bridge arm based on the relationship between the code value and the determination threshold.

[0007] Optionally, before comparing the collector-emitter voltage with a preset voltage threshold, the process includes: obtaining the execution command of the converter valve in the current control cycle; matching the collector-emitter voltage of each IGBT with the conduction command of each IGBT in the execution command, and determining whether the collector-emitter voltage of each IGBT is reliable data; if it is not reliable data, the obtained collector-emitter voltage is discarded.

[0008] Optionally, the collector-emitter voltage is compared with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle, including: obtaining a preset number of voltage threshold levels based on the rated operating conditions of the actual operation of the converter valve; comparing the collector-emitter voltage with the voltage threshold levels to determine the level of the collector-emitter voltage; and generating the corresponding code value based on the level of the collector-emitter voltage.

[0009] Optionally, determining the blocked converter valve bridge arm based on the relationship between the code value and the determination threshold includes: determining whether to block the converter valve bridge arm based on the number of sub-modules in each bridge arm whose code value exceeds a first determination threshold; determining whether to block all bridge arms based on the number of sub-modules in all bridge arms whose code value exceeds a second determination threshold; and determining whether to block all converter valve bridge arms based on the relationship between the difference between the sum of the code values ​​of the three-phase upper bridge arms and the sum of the code values ​​of the three-phase lower bridge arms and a third determination threshold.

[0010] Optionally, the flexible DC converter valve protection method further includes: acquiring the average value of the bridge arm code and the bridge arm current collected by the current sensor; determining whether the bridge arm current sensor is abnormal based on the relationship between the ratio of the average value of the bridge arm code and the bridge arm current of the three-phase upper bridge arm of the converter valve and the ratio of the average value of the bridge arm code and the bridge arm current of the three-phase lower bridge arm of the converter valve.

[0011] Optionally, obtaining the average value of the bridge arm code value and the bridge arm current collected by the current sensor includes: obtaining the instantaneous value of the bridge arm current collected by the bridge arm current sensor; calculating the effective value of the bridge arm current within a preset time based on the instantaneous value of the bridge arm current; and determining the average value of the bridge arm code value based on the ratio of the sum of the code values ​​of each bridge arm to the preset time.

[0012] Optionally, the abnormality of the bridge arm current sensor is determined based on the relationship between the average value of the three-phase upper bridge arm code value and the ratio of the bridge arm current to the average value of the three-phase lower bridge arm code value and the ratio of the bridge arm current. This includes: determining a judgment coefficient based on the ratio of the average value of the bridge arm code value to the effective value of the bridge arm current for each bridge arm; and determining the abnormality of the bridge arm current sensor based on the relationship between the difference between the sum of the judgment coefficients of the three-phase upper bridge arms and the sum of the judgment coefficients of the three-phase lower bridge arms and the fourth judgment threshold.

[0013] A second aspect of the present invention provides a flexible DC converter valve protection device, comprising: a voltage acquisition module for acquiring the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; a code value generation module for comparing the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT during the current control cycle; and a protection module for determining the blocked converter valve bridge arm based on the relationship between the code value and a judgment threshold.

[0014] Optionally, the flexible DC converter valve protection device further includes: a reliable data judgment module, specifically used to obtain the execution command of the converter valve in the current control cycle; to match the collector-emitter voltage of each IGBT with the conduction command of each IGBT in the execution command, and to determine whether the collector-emitter voltage of each IGBT is reliable data; when it is not reliable data, the obtained collector-emitter voltage is discarded.

[0015] Optionally, the code value generation module is specifically used to obtain a preset number of voltage threshold levels based on the rated operating conditions of the actual operation of the converter valve; compare the collector-emitter voltage with the voltage threshold levels to determine the level of the collector-emitter voltage; and generate a corresponding code value based on the level of the collector-emitter voltage.

[0016] Optionally, the protection module is specifically configured to determine whether to lock the converter valve bridge arm based on the number of sub-modules whose code values ​​in each bridge arm exceed a first determination threshold; determine whether to lock all bridge arms based on the number of sub-modules whose code values ​​in all bridge arms exceed a second determination threshold; and determine whether to lock all converter valve bridge arms based on the relationship between the difference between the sum of the code values ​​of the three-phase upper bridge arms and the sum of the code values ​​of the three-phase lower bridge arms and a third determination threshold.

[0017] Optionally, the flexible DC converter valve protection device further includes: a parameter acquisition module for acquiring the average value of the bridge arm code and the bridge arm current collected by the current sensor; and an anomaly judgment module for determining whether the bridge arm current sensor is abnormal based on the relationship between the ratio of the average value of the upper bridge arm code and the bridge arm current of the three-phase converter valve and the ratio of the average value of the lower bridge arm code and the bridge arm current of the three-phase converter valve.

[0018] Optionally, the parameter acquisition module is specifically used to acquire the instantaneous value of the bridge arm current obtained by the bridge arm current sensor; calculate the effective value of the bridge arm current within a preset time based on the instantaneous value of the bridge arm current; and determine the average value of the bridge arm code value based on the ratio of the sum of the code values ​​of each bridge arm to the preset time.

[0019] Optionally, the anomaly detection module is specifically used to determine the judgment coefficient based on the ratio of the average value of the bridge arm code value of each bridge arm to the effective value of the bridge arm current; and to determine whether the bridge arm current sensor is abnormal based on the relationship between the sum of the judgment coefficients of the three-phase upper bridge arm of the converter valve and the sum of the judgment coefficients of the three-phase lower bridge arm of the converter valve and the fourth judgment threshold.

[0020] A third aspect of the present invention provides a flexible DC converter valve protection system, comprising: an IGBT driver for acquiring the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; for comparing the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT during the current control cycle; and a converter valve base control system for determining the blocked converter valve bridge arm based on the relationship between the code value and the determination threshold.

[0021] A fourth aspect of the present invention provides a computer-readable storage medium storing computer instructions for causing the computer to perform the flexible DC converter valve protection method as described in the first aspect and any one of the first aspects of the present invention.

[0022] A fifth aspect of the present invention provides an electronic device, including: a memory and a processor, wherein the memory and the processor are communicatively connected to each other, the memory stores computer instructions, and the processor executes the computer instructions to perform the flexible DC converter valve protection method as described in the first aspect and any one of the first aspects of the present invention.

[0023] The technical solution provided by this invention has the following effects:

[0024] The flexible DC converter valve protection method, device, storage medium, and electronic equipment provided in this invention acquire the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; compare the collector-emitter voltage with a preset voltage threshold to determine the code value corresponding to each IGBT during the current control cycle; and determine the blocked converter valve arm based on the relationship between the code value and the judgment threshold. Therefore, compared to the large sampling delay of arm current sensors, this protection method does not rely on traditional arm current sensors, enabling more accurate and rapid acquisition of the overcurrent state of the flexible DC converter valve and the implementation of corresponding protection measures, thus improving the reliability of converter valve protection.

[0025] The flexible DC converter valve protection method provided in this invention can discard unreliable data in the acquired collector-emitter voltage by judging reliable data, thereby improving the accuracy of subsequent protection judgment.

[0026] The flexible DC converter valve protection method provided in this invention obtains the average value of the bridge arm code and the bridge arm current collected by the current sensor; it determines whether the bridge arm current sensor is abnormal based on the relationship between the ratio of the average value of the upper bridge arm code and the bridge arm current of the three-phase converter valve and the ratio of the average value of the lower bridge arm code and the bridge arm current of the three-phase converter valve. This achieves accurate identification of bridge arm current sensor faults through data processing of the collector-emitter voltage, solving the problem of unidentifiable bridge arm current sensor faults. It effectively improves the safety margin and fault ride-through capability of the flexible DC transmission system. Attached Figure Description

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0028] Figure 1 This is a flowchart of a flexible DC converter valve protection method according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the half-bridge submodule structure according to an embodiment of the present invention;

[0030] Figure 3 This is a logic diagram of the overcurrent protection method for bridge arm I section according to an embodiment of the present invention;

[0031] Figure 4 This is a structural block diagram of a flexible DC converter valve protection device according to an embodiment of the present invention;

[0032] Figure 5 This is a structural block diagram of a flexible DC converter valve protection system according to an embodiment of the present invention;

[0033] Figure 6 This is a schematic diagram of the structure of a computer-readable storage medium provided according to an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the structure of an electronic device provided according to an embodiment of the present invention. Detailed Implementation

[0035] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0036] The terms "first," "second," "third," "fourth," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] According to an embodiment of the present invention, a method for protecting a flexible DC converter valve is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0038] This embodiment provides a flexible DC converter valve protection method, which can be used in electronic devices such as computers, mobile phones, and tablets. Figure 1 This is a flowchart of a flexible DC converter valve protection method according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0039] Step S101: Obtain the collector-emitter voltage of each IGBT in the converter valve during the current control cycle. Specifically, the converter valve includes multiple bridge arms, and each bridge arm includes multiple sub-modules, such as... Figure 2 As shown, each half-bridge submodule includes an upper IGBT and a lower IGBT. For example, an MMC converter valve typically includes six bridge arms: phase A upper bridge arm, phase A lower bridge arm, phase B upper bridge arm, phase B lower bridge arm, phase C upper bridge arm, and phase C lower bridge arm. Each bridge arm usually contains several hundred submodules, and the number of submodules in each bridge arm is specifically set according to the actual situation.

[0040] In one embodiment, a digital IGBT driver can be used to acquire the collector-emitter voltage of each IGBT in the converter valve, and the acquired collector-emitter voltage can be uploaded to the valve base controller (VBC) for protection determination. The collector-emitter voltage can be acquired in real time or according to a control cycle, which can be the protection determination step size of the valve base controller, for example, 30µs–100µs.

[0041] Step S102: Compare the collector-emitter voltage with the preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle; specifically, the preset voltage threshold level can be predetermined; after the collector-emitter voltage is obtained, the digital IGBT driver compares the collector-emitter voltage with the preset voltage threshold level to determine which voltage threshold level the collector-emitter voltage is at, thereby determining the corresponding code value, and uploading the corresponding code value together with the collector-emitter voltage to the converter valve base control system.

[0042] Step S103: Determine the blocked converter valve arm based on the relationship between the code value and the judgment threshold. Specifically, the judgment threshold can be determined based on the actual operating conditions of the converter valve and the overcurrent tolerance of the IGBT. Compare the code value with the judgment threshold. If the code value exceeds the judgment threshold, it indicates that an overcurrent has occurred in the submodule where the corresponding IGBT is located. Determine whether to block the converter valve arm based on the overcurrent condition of the submodule.

[0043] The flexible DC converter valve protection method provided in this invention acquires the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; compares the collector-emitter voltage with a preset voltage threshold to determine the code value corresponding to each IGBT during the current control cycle; and determines the blocked converter valve arm based on the relationship between the code value and the judgment threshold. Therefore, compared to the large sampling delay of arm current sensors, this protection method does not rely on traditional arm current sensors, enabling more accurate and rapid acquisition of the overcurrent state of the flexible DC converter valve and the implementation of corresponding protection measures, thus improving the reliability of converter valve protection.

[0044] In one embodiment, before comparing the collector-emitter voltage with a preset voltage threshold, the following steps are included:

[0045] Step S201: Obtain the execution command of the converter valve in the current control cycle; specifically, during the operation of the converter valve, the corresponding IGBT will be controlled to operate according to the received execution command. Therefore, in order to determine whether the obtained collector-emitter voltage is reliable data, it is necessary to first obtain the execution command of the converter valve in the current control cycle.

[0046] Step S202: Match the collector-emitter voltage of each IGBT with the conduction command of each IGBT in the execution instruction, and determine whether the collector-emitter voltage of each IGBT is reliable data. Specifically, the execution instruction includes the conduction command of each IGBT in each sub-module of each bridge arm. Therefore, the IGBT that is turned on in the current control cycle is determined according to the conduction command included in the execution instruction. For example, if it is determined that the upper IGBT in a certain sub-module is turned on, and the collector-emitter voltage of the IGBT is positive according to the obtained collector-emitter voltage, it means that the IGBT is actually carrying current, and the collector-emitter voltage of the IGBT is reliable data. As another example, if it is determined that the lower IGBT in a certain sub-module is turned on, and the collector-emitter voltage of the IGBT is positive according to the obtained collector-emitter voltage, it means that the IGBT is actually carrying current, and the collector-emitter voltage of the IGBT is reliable data.

[0047] Step S203: If the data is not reliable, discard the acquired collector-emitter voltage. Through the above steps, each conducting IGBT is matched with the acquired collector-emitter voltage. If a match is found, the data is considered reliable. Alternatively, the acquired collector-emitter voltage can be used to determine whether the corresponding IGBT has received a corresponding turn-on command. If a turn-on command is received, the collector-emitter voltage is considered reliable data. Collector-emitter voltage data that cannot be matched or does not have a corresponding turn-on command is not reliable data and is discarded without further protection checks.

[0048] Specifically, by judging the actual current-carrying IGBT or reliable data, unreliable data in the acquired collector-emitter voltage can be discarded, thereby improving the accuracy of subsequent protection decisions.

[0049] In one embodiment, the collector-emitter voltage is compared with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle, including the following steps:

[0050] Step S301: Based on the rated operating conditions of the converter valve, obtain a preset number of voltage threshold levels. Specifically, the voltage corresponding to the arm current under rated operating conditions can be used as a reference, and multiple levels can be equally spaced within a certain range above this. For example, if the reference is defined as 1pu, then the range of 1pu-2pu can be equally spaced. If it is divided into ten segments, then the ten voltage threshold levels are U. set0 =1pu,U set1 =1.1pu, U set2 =1.2pu, ... U set10 =2pu.

[0051] Step S302: Compare the collector-emitter voltage with the voltage threshold level to determine the level at which the collector-emitter voltage is located.

[0052] Step S303: Generate the corresponding code value according to the position of the collector-emitter voltage.

[0053] Specifically, the collector-emitter voltage is compared with each voltage threshold level to determine which two levels the collector-emitter voltage falls between, and then the corresponding code value is generated. For example, if the collector-emitter voltage Vce satisfies U set2 <Vce<U set3 The generated code value is 2; U set3 <Vce<U set4 If the value is 3, then the generated code value is 3, and so on. The correspondence between the gear position and the code value can be predetermined.

[0054] In one embodiment, determining the locked-out converter valve bridge arm based on the relationship between the code value and the determination threshold includes the following steps:

[0055] Step S401: Determine whether to lock the converter valve bridge arm based on the number of sub-modules in each bridge arm whose code value exceeds the first determination threshold; specifically, when the valve base control system obtains the code value corresponding to the IGBT, as follows: Figure 3 As shown, first determine whether the code value exceeds the first determination threshold TH. pro1 (TH pro1 The settings are configured based on the actual operating conditions of the system and the overcurrent tolerance of the IGBT devices, for example, it can be set to 5); when the code value corresponding to a certain IGBT exceeds the first judgment threshold, it indicates that the submodule corresponding to that IGBT has experienced an I-segment overcurrent; then, the number of submodules experiencing overcurrent in each bridge arm is counted; if the number of submodules experiencing overcurrent in a certain bridge arm exceeds the first threshold within a certain period of time, it is determined that the corresponding bridge arm has experienced overcurrent, and the corresponding bridge arm is locked. The first threshold can be the total number of submodules in the bridge arm multiplied by the first judgment coefficient Kx. ro1 (K pro1 The value can be 0.3). A certain period of time is the short-term blocking determination time. Both the first determination coefficient and the short-term blocking determination time can be determined according to the fault characteristics of the flexible DC system and the protection setting requirements.

[0056] It should be noted that during the blocking of a bridge arm experiencing overcurrent, if the short-time blocking determination time T... rnc If the code value of the IGBT in the continuously unattended module is greater than the first judgment threshold, then the bridge arm will be unlocked again.

[0057] Step S402: Determine whether to block all bridge arms based on the number of sub-modules whose code values ​​exceed the second determination threshold in all bridge arms; specifically, based on the judgment of a single bridge arm, the code value corresponding to the acquired IGBT and the second determination threshold TH can also be used. pro2 (TH pro2The settings are configured based on the actual operating conditions of the system and the overcurrent tolerance of the IGBT devices. For example, it can be set to 8) for comparison to determine whether the submodule containing the IGBT has experienced a stage II overcurrent (the degree of stage II overcurrent is greater than stage I overcurrent). The total number of submodules in all bridge arms experiencing stage II overcurrent within the current control cycle is counted. If this total exceeds the second threshold, it is determined that the converter valve has experienced a stage II overcurrent. The VBC issues a protection command to lock the entire converter valve and requests the shutdown of the flexible DC system. The second threshold can be the total number of submodules in all bridge arms multiplied by the second judgment coefficient K. pro2 .

[0058] Step S403: Determine whether to block all converter valve arms based on the relationship between the difference between the sum of the code values ​​of the three-phase upper bridge arms and the sum of the code values ​​of the three-phase lower bridge arms, and the third judgment threshold. In addition to performing stage I and stage II overcurrent protection, differential current protection for the converter valve arms can also be performed based on the code values. Specifically, the VBC sums the code values ​​of all IGBTs actually carrying current in the three-phase (A-phase, B-phase, C-phase) upper bridge arms of the converter valve uploaded by the IGBT driver to obtain U. sum_up Then, sum the code values ​​of all the IGBTs with actual current flow in the three-phase lower bridge arm uploaded by the IGBT driver to obtain U. sum_down If the absolute value of the difference between the two is greater than the third judgment threshold TH pro3 If the current differential protection of the converter valve bridge arm is triggered, the VBC will issue a protection command to lock the entire converter valve and request the system to shut down.

[0059] In one embodiment, the flexible DC converter valve protection method further includes the following steps:

[0060] Step S501: Obtain the average value of the bridge arm code value and the bridge arm current collected by the current sensor; specifically, obtain the instantaneous value of the bridge arm current collected by the bridge arm current sensor; calculate the effective value of the bridge arm current within a preset time based on the instantaneous value of the bridge arm current; determine the average value of the bridge arm code value based on the ratio of the sum of the code values ​​of each bridge arm to the preset time. The sum of the code values ​​of each bridge arm is the sum of the code values ​​corresponding to all IGBTs that actually carry current in each bridge arm; the preset time can be determined according to actual needs, for example, it can be 500ms.

[0061] Step S502: Determine whether the arm current sensor is abnormal based on the relationship between the ratio of the average code value of the three-phase upper arm of the converter valve to the arm current and the ratio of the average code value of the three-phase lower arm of the converter valve to the arm current. Specifically, determine the judgment coefficient based on the ratio of the average arm code value of each arm to the effective value of the arm current; determine whether the arm current sensor is abnormal based on the relationship between the difference between the sum of the judgment coefficients of the three-phase upper arm of the converter valve and the sum of the judgment coefficients of the three-phase lower arm of the converter valve and the fourth judgment threshold.

[0062] The determination coefficient for each bridge arm is obtained by dividing the average code value of each bridge arm by the effective value of the bridge arm current. Then, the determination coefficients of the three upper-phase bridge arms are added together, and the determination data of the three lower-phase bridge arms are added together. The difference between the two sums is calculated. If the absolute value of the difference is greater than a fourth determination threshold, the bridge arm CT device is determined to be faulty, and the VBC requests a switch to another bridge arm CT device.

[0063] The flexible DC converter valve protection method provided in this invention obtains the average value of the bridge arm code and the bridge arm current collected by the current sensor; it determines whether the bridge arm current sensor is abnormal based on the relationship between the ratio of the average value of the upper bridge arm code and the bridge arm current of the three-phase converter valve and the ratio of the average value of the lower bridge arm code and the bridge arm current of the three-phase converter valve. This achieves accurate identification of bridge arm current sensor faults through data processing of the collector-emitter voltage, solving the problem of unidentifiable bridge arm current sensor faults. It effectively improves the safety margin and fault ride-through capability of the flexible DC transmission system.

[0064] This invention also provides a flexible DC converter valve protection device, such as... Figure 4 As shown, the device includes:

[0065] The voltage acquisition module is used to acquire the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; for details, please refer to the corresponding part of the above method embodiment, which will not be repeated here.

[0066] The code value generation module is used to compare the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle; for details, please refer to the corresponding part of the above method embodiment, which will not be repeated here.

[0067] The protection module is used to determine the blocked converter valve bridge arm based on the relationship between the code value and the judgment threshold. For details, please refer to the corresponding section of the above method embodiment; it will not be repeated here.

[0068] The flexible DC converter valve protection device provided in this invention acquires the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; compares the collector-emitter voltage with a preset voltage threshold to determine the code value corresponding to each IGBT during the current control cycle; and determines the blocked converter valve arm based on the relationship between the code value and the judgment threshold. Therefore, compared to the large sampling delay of the arm current sensor, this protection device does not rely on the traditional arm current sensor, enabling it to more accurately and quickly acquire the overcurrent state of the flexible DC converter valve and take corresponding protective measures, thus improving the reliability of the converter valve protection.

[0069] For a detailed description of the functions of the flexible DC converter valve protection device provided in this embodiment, please refer to the description of the flexible DC converter valve protection method in the above embodiments.

[0070] Optionally, the flexible DC converter valve protection device further includes: a reliable data judgment module, specifically used to obtain the execution command of the converter valve in the current control cycle; to match the collector-emitter voltage of each IGBT with the conduction command of each IGBT in the execution command, and to determine whether the collector-emitter voltage of each IGBT is reliable data; when it is not reliable data, the obtained collector-emitter voltage is discarded.

[0071] Optionally, the code value generation module is specifically used to obtain a preset number of voltage threshold levels based on the rated operating conditions of the actual operation of the converter valve; compare the collector-emitter voltage with the voltage threshold levels to determine the level of the collector-emitter voltage; and generate a corresponding code value based on the level of the collector-emitter voltage.

[0072] Optionally, the protection module is specifically configured to determine whether to lock the converter valve bridge arm based on the number of sub-modules whose code values ​​in each bridge arm exceed a first determination threshold; determine whether to lock all bridge arms based on the number of sub-modules whose code values ​​in all bridge arms exceed a second determination threshold; and determine whether to lock all converter valve bridge arms based on the relationship between the difference between the sum of the code values ​​of the three-phase upper bridge arms and the sum of the code values ​​of the three-phase lower bridge arms and a third determination threshold.

[0073] Optionally, the flexible DC converter valve protection device further includes: a parameter acquisition module for acquiring the average value of the bridge arm code and the bridge arm current collected by the current sensor; and an anomaly judgment module for determining whether the bridge arm current sensor is abnormal based on the relationship between the ratio of the average value of the upper bridge arm code and the bridge arm current of the three-phase converter valve and the ratio of the average value of the lower bridge arm code and the bridge arm current of the three-phase converter valve.

[0074] Optionally, the parameter acquisition module is specifically used to acquire the instantaneous value of the bridge arm current obtained by the bridge arm current sensor; calculate the effective value of the bridge arm current within a preset time based on the instantaneous value of the bridge arm current; and determine the average value of the bridge arm code value based on the ratio of the sum of the code values ​​of each bridge arm to the preset time.

[0075] Optionally, the anomaly detection module is specifically used to determine the judgment coefficient based on the ratio of the average value of the bridge arm code value of each bridge arm to the effective value of the bridge arm current; and to determine whether the bridge arm current sensor is abnormal based on the relationship between the sum of the judgment coefficients of the three-phase upper bridge arm of the converter valve and the sum of the judgment coefficients of the three-phase lower bridge arm of the converter valve and the fourth judgment threshold.

[0076] This invention also provides a flexible DC converter valve protection system, such as... Figure 5As shown, the system includes: an IGBT driver for acquiring the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; for comparing the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT during the current control cycle; and a converter valve base control system for determining the locked converter valve bridge arm based on the relationship between the code value and the judgment threshold.

[0077] The flexible DC converter valve protection system provided in this invention acquires the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; compares the collector-emitter voltage with a preset voltage threshold to determine the code value corresponding to each IGBT during the current control cycle; and determines the blocked converter valve arm based on the relationship between the code value and the judgment threshold. Therefore, compared to the large sampling delay of traditional arm current sensors, this protection system does not rely on traditional arm current sensors, enabling it to more accurately and quickly acquire the overcurrent state of the flexible DC converter valve and take corresponding protective measures, thus improving the reliability of the converter valve protection.

[0078] For a detailed description of the functions of the flexible DC converter valve protection system provided in this embodiment, please refer to the description of the flexible DC converter valve protection method in the above embodiments.

[0079] This invention also provides a storage medium, such as... Figure 6 As shown, a computer program 601 is stored on it. When executed by a processor, this program implements the steps of the flexible DC converter valve protection method described in the above embodiments. The storage medium also stores audio and video stream data, feature frame data, interactive request signaling, encrypted data, and a preset data size. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium may also include combinations of the above types of memory.

[0080] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The program can be stored in a computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), random access memory (RAM), flash memory, hard disk drive (HDD), or solid-state drive (SSD), etc.; the storage medium can also include combinations of the above types of memory.

[0081] This invention also provides an electronic device, such as... Figure 7 As shown, the electronic device may include a processor 51 and a memory 52, wherein the processor 51 and the memory 52 may be connected via a bus or other means. Figure 7 Taking the example of a connection between China and Israel via a bus.

[0082] Processor 51 can be a central processing unit (CPU). Processor 51 can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or combinations of the above types of chips.

[0083] The memory 52, as a non-transitory computer-readable storage medium, can be used to store non-transitory software programs, non-transitory computer-executable programs, and modules, such as the corresponding program instructions / modules in the embodiments of the present invention. The processor 51 executes various functional applications and data processing by running the non-transitory software programs, instructions, and modules stored in the memory 52, thereby implementing the flexible DC converter valve protection method in the above method embodiments.

[0084] The memory 52 may include a program storage area and a data storage area. The program storage area may store applications required for operating the device and at least one function; the data storage area may store data created by the processor 51, etc. Furthermore, the memory 52 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some embodiments, the memory 52 may optionally include memory remotely located relative to the processor 51, and these remote memories may be connected to the processor 51 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0085] The one or more modules are stored in the memory 52, and when executed by the processor 51, they perform the following: Figure 1 The flexible DC converter valve protection method shown in embodiment -3.

[0086] For specific details regarding the aforementioned electronic devices, please refer to the relevant documentation. Figures 1 to 3 The relevant descriptions and effects in the illustrated embodiments are for understanding purposes only and will not be repeated here.

[0087] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A method for protecting a flexible DC converter valve, characterized in that, include: Obtain the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; The collector-emitter voltage is compared with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle. The locked-in converter valve bridge arm is determined based on the relationship between the code value and the judgment threshold; The collector-emitter voltage is compared with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle, including: Based on the rated operating conditions of the actual operation of the converter valve, obtain a preset number of voltage threshold levels; The collector-emitter voltage is compared with the voltage threshold level to determine the level at which the collector-emitter voltage is located; Generate a corresponding code value based on the position of the collector-emitter voltage; Also includes: Obtain the average value of the bridge arm code and the bridge arm current collected by the current sensor; The abnormality of the bridge arm current sensor is determined by the relationship between the ratio of the average code value of the three-phase upper bridge arm of the converter valve to the bridge arm current and the ratio of the average code value of the three-phase lower bridge arm of the converter valve to the bridge arm current.

2. The flexible DC converter valve protection method according to claim 1, characterized in that, Before comparing the collector-emitter voltage with the preset voltage threshold level, the following steps are included: Obtain the execution command of the converter valve in the current control cycle; The collector-emitter voltage of each IGBT is matched with the turn-on command of each IGBT in the execution command, and it is determined whether the collector-emitter voltage of each IGBT is reliable data. When the data is not reliable, the acquired collector-emitter voltage will be discarded.

3. The flexible DC converter valve protection method according to claim 1, characterized in that, Determining the locked-out converter valve arm based on the relationship between the code value and the determination threshold includes: Whether to lock the converter valve bridge arm is determined based on the number of sub-modules in each bridge arm whose code value exceeds the first determination threshold. Whether to lock all bridge arms is determined based on the number of sub-modules whose code values ​​exceed the second determination threshold in all bridge arms. The determination of whether to lock all converter valve arms is based on the relationship between the sum of the code values ​​of the three-phase upper bridge arm and the sum of the code values ​​of the three-phase lower bridge arm and the third judgment threshold.

4. The flexible DC converter valve protection method according to claim 1, characterized in that, Obtain the average value of the bridge arm code and the bridge arm current collected by the current sensor, including: Obtain the instantaneous value of the bridge arm current acquired by the bridge arm current sensor; The effective value of the bridge arm current within a preset time period is calculated based on the instantaneous value of the bridge arm current. The average value of the bridge arm code is determined by the ratio of the sum of the code values ​​of each bridge arm to the preset time.

5. The flexible DC converter valve protection method according to claim 4, characterized in that, The abnormality of the bridge arm current sensor is determined by the relationship between the ratio of the average code value of the three-phase upper bridge arm and the bridge arm current, and the ratio of the average code value of the three-phase lower bridge arm and the bridge arm current. This includes: The decision coefficient is determined based on the ratio of the average bridge arm code value to the effective value of the bridge arm current for each bridge arm. The abnormality of the bridge arm current sensor is determined by the relationship between the sum of the judgment coefficients of the three-phase upper bridge arm and the sum of the judgment coefficients of the three-phase lower bridge arm of the converter valve and the fourth judgment threshold.

6. A flexible DC converter valve protection device, characterized in that, include: The voltage acquisition module is used to acquire the collector-emitter voltage of each IGBT in the converter valve during the current control cycle. The code value generation module is used to compare the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT in the current control cycle. Specifically, the code value generation module is used to obtain a preset number of voltage threshold levels according to the rated operating conditions of the actual operation of the converter valve; compare the collector-emitter voltage with the voltage threshold level to determine the level at which the collector-emitter voltage is located. Generate a corresponding code value based on the position of the collector-emitter voltage; The protection module is used to determine the locked-out converter valve bridge arm based on the relationship between the code value and the judgment threshold. Also includes: Obtain the average value of the bridge arm code and the bridge arm current collected by the current sensor; The abnormality of the bridge arm current sensor is determined by the relationship between the ratio of the average code value of the three-phase upper bridge arm of the converter valve to the bridge arm current and the ratio of the average code value of the three-phase lower bridge arm of the converter valve to the bridge arm current.

7. A flexible DC converter valve protection system, characterized in that, The flexible DC converter valve protection method as described in any one of claims 1-5 includes: The IGBT driver is used to acquire the collector-emitter voltage of each IGBT in the converter valve during the current control cycle; and to compare the collector-emitter voltage with a preset voltage threshold level to determine the code value corresponding to each IGBT during the current control cycle. The converter valve base control system determines the locked converter valve bridge arm based on the relationship between the code value and the judgment threshold.

8. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions for causing the computer to perform the flexible DC converter valve protection method as described in any one of claims 1-5.

9. An electronic device, characterized in that, include: The system includes a memory and a processor, which are communicatively connected to each other. The memory stores computer instructions, and the processor executes the computer instructions to perform the flexible DC converter valve protection method as described in any one of claims 1-5.

Images