Method and device for controlling a bridge arm of a hybrid converter, and hybrid converter system

Abstract

The application relates to a hybrid converter valve bridge arm control method and device, a hybrid converter valve system, a medium and a computer program product. The bridge arm comprises a plurality of sub-modules of at least two different rated voltages, the method comprises: converting a required voltage of the bridge arm into a required degree of division and converting a rated voltage of the sub-modules into a rated degree of division according to a preset voltage reference value; determining an already-put-in degree of division of the bridge arm according to the rated degree of division of each sub-module in a put-in state; determining a target sub-module in each sub-module and switching an operating state of the target sub-module according to a degree of division difference between the already-put-in degree of division and the required degree of division, a current direction of the bridge arm and the rated degree of division of each sub-module; and the operating state comprises a put-in state and a cut-off state. The method is beneficial to reducing a deviation value between an output voltage of the converter valve and the required voltage, thereby improving the output performance of the converter valve.

Description

Technical Field

[0001] This application relates to the field of high-voltage power transmission technology, and in particular to a bridge arm control method, device, hybrid converter valve system, computer-readable storage medium, and computer program product for a hybrid converter valve. Background Technology

[0002] Flexible DC transmission systems typically employ submodules composed of fully controlled switching devices, insulated-gate bipolar transistors (IGBTs), to construct modular multilevel converters (MMCs). For ease of engineering control, maintenance, and operation, existing projects typically use submodules with a single rated voltage for each converter valve. However, when a converter valve requires the mixing of submodules with different rated voltages for grid connection, traditional single-type submodule control algorithms become inapplicable. This can easily lead to deviations between the converter valve's output voltage and the required voltage, affecting the converter valve's output performance. Summary of the Invention

[0003] Therefore, it is necessary to provide a bridge arm control method, device, hybrid valve system, computer-readable storage medium, and computer program product for hybrid converter valves that can improve the output performance of hybrid converter valves, in order to address the above-mentioned technical problems.

[0004] In a first aspect, this application provides a bridge arm control method for a hybrid converter valve, wherein the bridge arm comprises multiple sub-modules with at least two different rated voltages, and the method includes:

[0005] Based on the preset voltage reference value, the required voltage of the bridge arm is converted into the required differentiation, and the rated voltage of the submodule is converted into the rated differentiation.

[0006] The operational differentiation of the bridge arm is determined based on the rated differentiation of each sub-module that is in operation.

[0007] Based on the difference in discrimination between the discrimination of the input and the discrimination of the demand, the current direction of the bridge arm, and the rated discrimination of each submodule, the target submodule is determined in each submodule, and the operating state of the target submodule is switched; the operating state includes the input state and the cut-off state.

[0008] In one embodiment, based on the difference in discrimination between the already implemented discrimination and the required discrimination, the current direction of the bridge arm, and the rated discrimination of each submodule, the target submodule and the target switching state of the target submodule are determined in each submodule, including:

[0009] The preset input sub-module sequence or the preset cut-off sub-module sequence is determined as the target sequence based on the discrimination difference.

[0010] The target submodule is determined in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule.

[0011] In one embodiment, before determining the target submodule in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule, the method further includes:

[0012] The state of charge of the submodule is determined based on its rated voltage and actual voltage.

[0013] Based on the charge state of each submodule, the submodules in the input state and the submodules in the cut-off state are sorted to obtain a preset input submodule sequence and a preset cut-off submodule sequence.

[0014] In one embodiment, determining the state of charge of the submodule based on its rated voltage and actual voltage includes:

[0015] Determine the voltage difference between the rated voltage of the submodule and the maximum rated voltage among all submodules;

[0016] The submodule's state of charge is the sum of its actual voltage and the voltage difference.

[0017] In one embodiment, the target submodule is determined in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule, including:

[0018] Based on the discrimination difference and the rated discrimination of each submodule, determine the discrimination combination of the target submodule;

[0019] Based on the combination of current direction and discrimination, the target sub-module is determined in the target sequence.

[0020] In one embodiment, after obtaining the preset input submodule sequence and the preset removal submodule sequence, the method further includes:

[0021] Determine the deviation between the maximum actual voltage of the input submodule sequence and the minimum actual voltage of the output submodule sequence;

[0022] If the deviation value is greater than the preset equalization threshold, the first submodule corresponding to the maximum actual voltage of the input submodule sequence is switched to the cut-off state, and the second submodule in the cut-off submodule sequence with the same rated voltage as the first submodule and the smallest actual voltage is switched to the input state.

[0023] Secondly, this application also provides a bridge arm control device for a hybrid converter valve, wherein the bridge arm includes multiple sub-modules with at least two different rated voltages, and the device includes:

[0024] The conversion module is used to convert the required voltage of the bridge arm into the required discrimination value according to the preset voltage reference value, and to convert the rated voltage of the sub-module into the rated discrimination value.

[0025] The input module is used to determine the input differentiation of the bridge arm based on the rated differentiation of each sub-module in the input state.

[0026] The control module is used to determine the target submodule in each submodule based on the difference between the discrimination level already implemented and the required discrimination level, the current direction of the bridge arm, and the rated discrimination level of each submodule, and to switch the operating state of the target submodule.

[0027] Thirdly, this application also provides a hybrid converter valve system, including a hybrid converter valve and a controller. The hybrid converter valve includes multiple bridge arms, each bridge arm including multiple sub-modules with at least two different rated voltages. The controller is connected to each sub-module and is used to implement the following steps:

[0028] Based on the preset voltage reference value, the required voltage of the bridge arm is converted into the required differentiation, and the rated voltage of the submodule is converted into the rated differentiation.

[0029] The operational differentiation of the bridge arm is determined based on the rated differentiation of each sub-module that is in operation.

[0030] Based on the difference in discrimination between the discrimination already implemented and the discrimination required, the current direction of the bridge arm, and the rated discrimination of each submodule, the target submodule is determined in each submodule, and the operating status of the target submodule is switched.

[0031] Fourthly, this application also provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, performs the following steps:

[0032] Based on the preset voltage reference value, the required voltage of the bridge arm is converted into the required differentiation, and the rated voltage of the submodule is converted into the rated differentiation.

[0033] The operational differentiation of the bridge arm is determined based on the rated differentiation of each sub-module that is in operation.

[0034] Based on the difference in discrimination between the discrimination already implemented and the discrimination required, the current direction of the bridge arm, and the rated discrimination of each submodule, the target submodule is determined in each submodule, and the operating status of the target submodule is switched.

[0035] Fifthly, this application also provides a computer program product, including a computer program that, when executed by a processor, performs the following steps:

[0036] Based on the preset voltage reference value, the required voltage of the bridge arm is converted into the required differentiation, and the rated voltage of the submodule is converted into the rated differentiation.

[0037] The operational differentiation of the bridge arm is determined based on the rated differentiation of each sub-module that is in operation.

[0038] Based on the difference in discrimination between the discrimination already implemented and the discrimination required, the current direction of the bridge arm, and the rated discrimination of each submodule, the target submodule is determined in each submodule, and the operating status of the target submodule is switched.

[0039] The aforementioned hybrid converter valve arm control method, device, hybrid converter valve system, computer-readable storage medium, and computer program product convert the required voltage of the bridge arm and the rated voltage of each sub-module into a distinguishability scale based on the same voltage reference value. This allows sub-modules with different rated voltages to be measured and compared on the same basis. Then, based on the distinguishability difference between the input distinguishability and the required distinguishability, the current direction of the bridge arm, and the rated distinguishability of each sub-module, the target sub-module and its switching state are jointly determined. This allows the target sub-module and its switching state that can make the output voltage of the bridge arm follow the required voltage to be selected with the reference value as the smallest unit. This reduces the deviation between the output voltage and the required voltage of the converter valve, thereby improving the output performance of the converter valve. Attached Figure Description

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

[0041] Figure 1 This is a diagram illustrating the application environment of the bridge arm control method for a hybrid converter valve in one embodiment.

[0042] Figure 2 This is a flowchart illustrating the bridge arm control method for a hybrid converter valve in one embodiment.

[0043] Figure 3 This is a detailed flowchart illustrating the steps of determining the target submodule and the target switching state of the target submodule in each submodule based on the difference between the discrimination level already implemented and the required discrimination level, the current direction of the bridge arm, and the rated discrimination level of each submodule in one embodiment.

[0044] Figure 4 This is a flowchart illustrating the bridge arm control method for a hybrid converter valve in one embodiment.

[0045] Figure 5 This is a detailed flowchart illustrating the steps for determining the state of charge of a submodule based on its rated voltage and actual voltage in one embodiment.

[0046] Figure 6 This is a detailed flowchart illustrating the steps for determining a target submodule in a target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule in one embodiment.

[0047] Figure 7 This is a detailed flowchart illustrating the bridge arm control method for a hybrid converter valve in one embodiment.

[0048] Figure 8 This is a flowchart illustrating the bridge arm control method for a hybrid converter valve in one embodiment.

[0049] Figure 9 This is an example flowchart of a bridge arm control method for a hybrid converter valve in one embodiment;

[0050] Figure 10 This is a structural block diagram of the bridge arm control device for a hybrid converter valve in one embodiment;

[0051] Figure 11 This is an internal structural diagram of a hybrid converter valve system in one embodiment. Detailed Implementation

[0052] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0053] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0054] The bridge arm control method for the hybrid converter valve provided in this application embodiment can be applied to, for example... Figure 1 The hybrid converter valve system shown includes a controller 1200 and a converter valve 1100. The converter valve 1100 includes multiple bridge arms 1110, and each bridge arm 1110 includes multiple sub-modules 1111 with at least two different rated voltages. The multiple sub-modules 1111 in the bridge arm 1110 are connected in series.

[0055] In the converter valve system, the DC side of bridge arm 1110 is connected to a DC power source. Controller 1200 controls the on / off states of numerous sub-modules 1111 in each bridge arm 1110, causing the output of bridge arm 1110 to exhibit a multi-level stepped voltage. After filtering by a connected reactor, this voltage approximates an ideal sine wave, thus achieving power transfer between the AC and DC sides. During the operation of converter valve 1100, controller 1200 needs to adjust the number of on / off sub-modules 1111 in bridge arm 1110 in real time to ensure that the overall output voltage of bridge arm 1110 follows the required voltage, meeting the needs of subsequent connected equipment.

[0056] In this embodiment, to control a bridge arm 1110 comprising multiple sub-modules 1111 with at least two different rated voltages, the controller 1200 converts the required voltage of the bridge arm 1110 into a required differentiation degree based on a preset voltage reference value, and converts the rated voltage of the sub-modules 1111 into a rated differentiation degree; then, based on the rated differentiation degree of each sub-module 1111 in the engaged state, the controller determines the engaged differentiation degree of the bridge arm 1110; finally, based on the differentiation degree difference between the engaged differentiation degree and the required differentiation degree, the current direction of the bridge arm 1110, and the rated differentiation degree of each sub-module 1111, the controller determines the target sub-module and the target switching state of the target sub-module in each sub-module 1111, and controls the target sub-module based on the target switching state, thereby adjusting the number of engaged sub-modules 1111 and the rated voltage value in the bridge arm 1110 based on the voltage reference value, thus realizing the control of a bridge arm 1110 comprising multiple sub-modules 1111 with at least two different rated voltages, so that the overall output voltage of the bridge arm 1110 can follow the required voltage.

[0057] In one exemplary embodiment, such as Figure 2 As shown, a bridge arm control method for a hybrid converter valve is provided, which is applied to... Figure 1 Taking controller 1200 as an example, the explanation includes the following steps 202 to 206. Wherein:

[0058] Step 202: Based on the preset voltage reference value, convert the required voltage of the bridge arm into the required differentiation value, and convert the rated voltage of the submodule into the rated differentiation value.

[0059] The voltage reference value refers to the value that can be divided by the rated voltage of all different rated voltage submodules in the bridge arm, and can be the greatest common divisor of different rated voltages. The demand differentiation refers to the number of reference voltage units required by the bridge arm under its current operating conditions, obtained by dividing the bridge arm's required voltage by the voltage reference value and rounding up. The rated differentiation refers to the integer value obtained by dividing the rated voltage of a single submodule by the voltage reference value. For example, if the bridge arm contains two types of submodules with rated voltages of 1.6 kV and 2.0 kV, and their greatest common divisor is 0.4 kV, then the voltage reference value is 0.4 kV; the rated differentiation of the 1.6 kV submodule is 4, and the rated differentiation of the 2.0 kV submodule is 5; if the bridge arm requires a voltage of 20 kV, then the demand differentiation is 20 divided by 0.4 and rounded up to 50.

[0060] In this embodiment, the controller acquires a preset voltage reference value. Upon receiving a demand voltage command for the bridge arm from the host computer or user, it divides the demand voltage by the voltage reference value and performs an up-rounding operation on the result to obtain the demand discrimination index. Simultaneously, the controller reads the rated voltage parameters of each submodule, divides each rated voltage by the voltage reference value, and obtains the rated discrimination index for each submodule, thus using the same reference value to measure the demand voltage against different rated voltages.

[0061] Step 204: Determine the operational differentiation of the bridge arm based on the rated differentiation of each sub-module in the operational state.

[0062] The "already engaged differentiation" refers to the sum of the rated differentiation of all submodules that are currently engaged in the bridge arm. This value reflects the total equivalent reference voltage unit currently engaged in the bridge arm. "Engaged state" refers to the operating state where the switching devices of a submodule are triggered and turned on, and the submodule is connected to the bridge arm current path.

[0063] In this embodiment, the controller acquires the current on / off status of all submodules in the bridge arm in real time and filters out the submodules that are in the active state. The controller acquires the rated discrimination degree corresponding to each active submodule, sums these rated discrimination degrees, and the sum is determined as the current active discrimination degree of the bridge arm.

[0064] Step 206: Based on the difference in discrimination between the discrimination already implemented and the required discrimination, the current direction of the bridge arm, and the rated discrimination of each submodule, determine the target submodule in each submodule and switch the operating status of the target submodule.

[0065] The operating status includes the engaged state and the disengaged state. The current direction refers to the instantaneous flow direction of the current in the bridge arm, which is used to determine whether the submodule capacitor is in a charging or discharging state.

[0066] In this embodiment, the controller calculates the difference between the required discrimination value and the already implemented discrimination value to obtain the discrimination value difference. Simultaneously, it acquires the current direction of the bridge arm to determine whether the bridge arm is currently in a discharging or charging state. Based on the sign and magnitude of the discrimination value difference, combined with the current direction and referring to the rated discrimination value of each submodule, the controller selects the target submodule from the submodules of the bridge arm that needs to be switched on or off. When the discrimination value difference is positive, it indicates that an additional submodule needs to be implemented; in this case, the controller prioritizes selecting the target submodule from the submodules currently in a disconnected state. When the discrimination value difference is negative, it indicates that a submodule needs to be disconnected; in this case, the controller prioritizes selecting the target submodule from the submodules currently in an implemented state. After determining the target submodule, the controller sets the state opposite to the current switching state of the target submodule as the target switching state and issues a trigger pulse corresponding to the target switching state to control the target submodule to switch to the opposite switching state.

[0067] By converting the required voltage of the bridge arm and the rated voltage of each submodule into a distinguishability scale based on the same voltage reference value, submodules with different rated voltages in the hybrid converter valve system can be measured and compared on the same basis. Then, based on the distinguishability difference between the implemented distinguishability and the required distinguishability, the current direction of the bridge arm, and the rated distinguishability of each submodule, the target submodule and its switching state are jointly determined. Thus, the target submodule and its switching state that can make the output voltage of the bridge arm follow the required voltage can be selected with the reference value as the smallest unit. This reduces the deviation between the output voltage and the required voltage of the converter valve, thereby improving the output performance of the converter valve.

[0068] In some embodiments, such as Figure 3 As shown, step 206 above includes steps 302 and 304. Wherein:

[0069] Step 302: Determine the target submodule in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule.

[0070] Step 304: Determine the target submodule in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule.

[0071] The preset input submodule sequence refers to the sequence generated by the controller in advance, which sorts the submodules currently in the input state in the bridge arm according to their state of charge. The preset cut-off submodule sequence refers to the sequence generated by the controller in advance, which sorts the submodules currently in the cut-off state in the bridge arm according to their state of charge.

[0072] In this embodiment, the controller determines the preset input submodule sequence or preset cut-off submodule sequence as the target sequence including the target submodule based on the sign of the discrimination difference. When the discrimination difference is positive, it indicates that an input submodule needs to be added. At this time, the controller will preferentially select the target submodule from the submodules that are currently in the cut-off state. When the discrimination difference is negative, it indicates that a cut-off submodule needs to be added. The controller will preferentially select the target submodule from the submodules that are currently in the input state.

[0073] In this embodiment, the controller determines the target switching state of the target submodule based on the sign of the discrimination difference. When the discrimination difference is positive, the target switching state of the target submodule is determined to be in the active state, and the controller controls the target submodule to switch from the current deactivated state to the active state. When the discrimination difference is negative, the target switching state of the target submodule is determined to be in the deactivated state, and the controller controls the target submodule to switch from the current active state to the deactivated state.

[0074] The target submodule and its switching state are jointly determined by the difference between the discrimination value already implemented and the required discrimination value, the current direction of the bridge arm, and the rated discrimination value of each submodule. This allows the target submodule and its switching state to be selected with the reference value as the smallest unit, so that the output voltage of the bridge arm can follow the required voltage. This reduces the deviation between the output voltage and the required voltage of the converter valve, thereby improving the output performance of the converter valve.

[0075] In some embodiments, such as Figure 4 As shown, prior to step 302 above, the bridge arm control method for the mixing converter valve further includes steps 402 and 404. Wherein:

[0076] Step 402: Determine the state of charge of the submodule based on its rated voltage and actual voltage.

[0077] Among them, the state of charge refers to the relative level of the current amount of charge stored in the capacitor inside the submodule, which is used to characterize the degree to which the voltage of the submodule is too high or too low. The state of charge can be determined by the ratio between the actual voltage of the submodule and the rated voltage.

[0078] In this embodiment, the controller acquires the actual voltage and the corresponding rated voltage of each submodule, and determines the state of charge (SOC) of the submodule based on the actual voltage and the rated voltage. In some embodiments, the controller can quantify the SOC of the submodule by calculating the ratio of the two. This ratio reflects the degree of deviation of the submodule's current voltage from its own rated voltage.

[0079] Step 404: Sort the submodules in the input state and the cut-off state according to the charge state of each submodule to obtain the preset input submodule sequence and the preset cut-off submodule sequence.

[0080] In this embodiment, the controller first identifies the current switching state of all submodules in the bridge arm and categorizes them into an active state group and an inactive state group. Within the active state group, submodules are sorted according to their state of charge (SBC) values ​​to generate a preset sequence of inactive submodules. Similarly, within the inactive state group, submodules are sorted according to their SBC values ​​to generate a preset sequence of active submodules.

[0081] Normalization of the state of charge eliminates the comparison barrier caused by the difference in rated voltage, allowing subsequent switching selection to be performed directly based on a clear queue order, thus reducing the execution time of the control algorithm.

[0082] In some embodiments, such as Figure 5 As shown, step 402 above includes steps 502 and 504. Wherein:

[0083] Step 502: Determine the voltage difference between the rated voltage of the submodule and the maximum rated voltage among all submodules.

[0084] In this embodiment, the controller acquires the rated voltage of all submodules in the bridge arm and selects the highest rated voltage as the maximum rated voltage. For each submodule, the controller subtracts its own rated voltage from the maximum rated voltage to obtain the voltage difference for that submodule. For submodules whose rated voltage is equal to the maximum rated voltage, the voltage difference is zero.

[0085] Step 504: The sum of the actual voltage of the submodule and the voltage difference is taken as the state of charge of the submodule.

[0086] In this embodiment, for each submodule, the controller adds the actual voltage to the voltage difference corresponding to that submodule, and the sum is defined as the state of charge of that submodule. For submodules with a rated voltage equal to the highest rated voltage, since the voltage difference is zero, their state of charge is equal to the actual voltage; for each submodule with a lower rated voltage, its actual voltage is uniformly increased by the difference between it and the highest rated voltage, so that the state of charge of all submodules is under the same voltage scale.

[0087] The above steps directly map the actual voltage of different rated voltage submodules to a unified maximum rated voltage scale through additive compensation. Without introducing floating-point operations through division, the unified quantization of voltage levels of submodules of different voltage levels is achieved, which helps to reduce the computational complexity and computational resource requirements of the controller.

[0088] In some embodiments, such as Figure 6 As shown, step 302 above includes steps 602 and 604. Wherein:

[0089] Step 602: Determine the discrimination combination of the target submodule based on the discrimination difference and the rated discrimination of each submodule.

[0090] In this embodiment, the controller obtains the absolute value of the discrimination difference, which represents the number of equivalent reference voltage units that need to be adjusted. The controller reads the rated discrimination of each submodule in the bridge arm and attempts to split it from largest to smallest, decomposing the absolute value of the discrimination difference into the sum of several rated discrimination values ​​to form a discrimination combination. During the splitting process, the controller prioritizes the splitting scheme that minimizes the error between the sum of the combinations and the absolute value of the discrimination difference. When multiple splitting schemes exist, the scheme with the fewest submodules is selected. Each discrimination value in this discrimination combination corresponds to the rated discrimination of a target submodule to be operated on.

[0091] Step 604: Determine the target sub-module in the target sequence based on the combination of current direction and discrimination.

[0092] In this embodiment, the controller determines the target submodule from either a preset input submodule sequence or a preset cut-off submodule sequence based on the sign of the discrimination difference. When the discrimination difference is positive, the controller selects submodules from the preset cut-off submodule sequence according to the order of their states of charge, sequentially choosing submodules that match the values ​​in the previously determined discrimination combinations. If the current direction is charging, selection starts from the end with the smaller state of charge in the cut-off submodule sequence; if the current direction is discharging, selection starts from the end with the larger state of charge. When the discrimination difference is negative, the controller selects submodules from the preset input submodule sequence according to the order of their states of charge, sequentially choosing submodules that match the values ​​in the discrimination combinations. If the current direction is charging, selection starts from the end with the larger state of charge in the input submodule sequence; if the current direction is discharging, selection starts from the end with the smaller state of charge in the input submodule sequence. The controller sequentially locates and determines the corresponding number of target submodules in the corresponding sequence according to each value in the discrimination combination.

[0093] Specifically, such as Figure 7As shown, when performing demand voltage tracking, the difference between the demand discrimination index and the discrimination index of the deployed sub-modules is first calculated. If the discrimination index difference is positive, it indicates that some sub-modules still need to be deployed. If the current direction of the current arm is charging, then in the sub-module removal sequence (removal group), the sub-module with the smaller voltage is selected from the side with the smaller state of charge and switched to the deployed state. If the current direction of the current arm is discharging, then in the sub-module removal sequence (removal group), the sub-module with the larger voltage is selected from the side with the larger state of charge and switched to the deployed state. Similarly, if the discrimination index difference is negative, it indicates that some sub-modules still need to be removed. If the current direction of the current arm is charging, then in the sub-module deployment sequence (deployment group), the sub-module with the larger voltage is selected from the side with the larger state of charge and switched to the deployed state. If the current direction of the current arm is discharging, then in the sub-module removal sequence (removal group), the sub-module with the smaller voltage is selected from the side with the smaller state of charge and switched to the deployed state. When selecting target sub-modules, it is necessary to fit the discrimination of the sub-modules and match the sub-module combinations according to the discrimination difference to ensure that the error between the sum of the discrimination of the target sub-modules and the discrimination difference is minimized.

[0094] For example, when the rated voltage of the converter valve submodule is 1.6kV and 2kV, the two rated values ​​correspond to submodule differentiation of 4 and 5 respectively. The submodule differentiation difference of 13 can be divided into a sequence of 5, 4, 4, corresponding to two 1.6kV submodules and one 2kV submodule. For example, if the rated voltages of the sub-modules in the cutoff group sequence, from smallest to largest charge state, are 1.6kV, 2kV, 2kV, 2kV, 1.6kV..., and the corresponding sub-module discrimination values ​​are 4, 5, 5, 5, 4..., and the corresponding sub-module numbers are (18), (9), (7), (6), (5)..., then strictly according to the sorting, the newly added input sub-module numbers should be (18), (9), (7), and the corresponding newly added input sub-module discrimination value is 4+5+5=14, which is 1 more than the difference of 13 with the input sub-module discrimination value. At this time, it is possible to consider determining the discrimination value of the target sub-module as 4, 5, 4, so that the discrimination value of the newly added input sub-module is equal to the discrimination value of the input sub-module. At this time, the target input sub-module numbers should be selected in ascending order as (18), (9), (5), so that the error between the sum of the discrimination values ​​of the target sub-modules and the discrimination value difference is minimized.

[0095] In some embodiments, such as Figure 8 As shown, after step 404 above, the bridge arm control method for the mixing converter valve further includes steps 802 and 804. Wherein:

[0096] Step 802: Determine the deviation between the maximum actual voltage of the input submodule sequence and the minimum actual voltage of the cut-off submodule sequence.

[0097] In this embodiment, the controller obtains the maximum actual voltage in the engaged submodule sequence and the minimum actual voltage in the disengaged submodule sequence, calculates the difference between the maximum and minimum actual voltages, and the resulting difference is the deviation value between the engaged and disengaged groups. The deviation value reflects the degree of voltage imbalance between engaged and disengaged submodules in the current bridge arm.

[0098] Step 804: When the deviation value is greater than the preset equalization threshold, control the first submodule corresponding to the maximum actual voltage of the input submodule sequence to switch to the cut-off state, and control the second submodule in the cut-off submodule sequence with the same rated voltage as the first submodule and the smallest actual voltage to switch to the input state.

[0099] In this embodiment, the controller compares the obtained deviation value with a preset voltage equalization threshold. When the deviation value is greater than the voltage equalization threshold, the controller locates the submodule with the highest actual voltage in the input submodule sequence and marks it as the first submodule. The controller obtains the rated voltage of the first submodule, filters all submodules with the same rated voltage as the first submodule in the output submodule sequence, selects the one with the lowest actual voltage from these submodules, and marks it as the second submodule. The controller controls the first submodule to switch from the input state to the output state, and simultaneously controls the second submodule to switch from the output state to the input state, completing one submodule exchange action between groups. After the exchange, the submodule with the highest voltage in the original input group exits the input state, and the submodule with the lowest voltage at the same rated voltage in the original output group enters the input state, thereby narrowing the voltage difference between the input group and the output group.

[0100] For example, such as Figure 9As shown, after determining the target submodule requiring switching based on the required voltage, the remaining submodules are grouped according to their rated voltage. Submodules in the active state are designated as the active group, and submodules in the deactivated state are designated as the deactivated group. When the bridge arm current direction is the charging direction, the deviation between the maximum actual voltage in the active group and the minimum actual voltage in the deactivated group is calculated. If the deviation is greater than the voltage equalization threshold, the first submodule with the highest actual voltage in the active group is deactivated, and the second submodule in the deactivated group, which has the same rated voltage as the first submodule and the lowest actual voltage, is activated. The trigger pulses for the first and second submodules are updated, switching their on / off states. If the deviation is less than or equal to the voltage equalization threshold, no switching occurs, and the original trigger pulses are maintained. Similarly, when the bridge arm current direction is the discharge direction, the deviation between the maximum actual voltage in the cut-off group and the minimum actual voltage in the input group is calculated. If the deviation is greater than the voltage equalization threshold, the first submodule with the largest actual voltage in the cut-off group is input, and the second submodule in the input group, which has the same rated voltage as the first submodule and the smallest actual voltage, is cut off. The trigger pulses of the first and second submodules are updated, and the switching states of the first and second submodules are switched. If the deviation is less than or equal to the voltage equalization threshold, no switching is performed, and the original trigger pulses are maintained.

[0101] It should be understood that although the steps in the flowcharts of the above embodiments are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the above embodiments may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0102] Based on the same inventive concept, this application also provides a bridge arm control device for implementing the bridge arm control method of the hybrid converter valve described above. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations of one or more embodiments of the bridge arm control device for hybrid converter valves provided below can be found in the limitations of the bridge arm control method for hybrid converter valves described above, and will not be repeated here.

[0103] In one exemplary embodiment, such as Figure 10 As shown, a bridge arm control device for a hybrid converter valve is provided, comprising:

[0104] The conversion module 1001 is used to convert the required voltage of the bridge arm into the required discrimination value according to the preset voltage reference value, and to convert the rated voltage of the sub-module into the rated discrimination value.

[0105] The input module 1002 is used to determine the input differentiation of the bridge arm based on the rated differentiation of each sub-module in the input state.

[0106] The control module 1003 is used to determine the target submodule in each submodule based on the difference between the discrimination of the input discrimination and the required discrimination, the current direction of the bridge arm and the rated discrimination of each submodule, and to switch the operating state of the target submodule; the operating state includes the input state and the disconnection state.

[0107] In one embodiment, the control module 1003 is further configured to determine the target submodule in the target sequence based on the discrimination difference, the current direction of the bridge arm and the rated discrimination of each submodule; and to determine the target switching state of the target submodule based on the difference in required discrimination.

[0108] In one embodiment, the control module 1003 is further configured to determine the state of charge of the submodule based on the rated voltage and actual voltage of the submodule; and to sort the submodules in the engaged state and the disengaged state according to the state of charge of each submodule to obtain a preset engaged submodule sequence and a preset disengaged submodule sequence.

[0109] In one embodiment, the control module 1003 is further configured to determine the voltage difference between the rated voltage of the submodule and the maximum rated voltage among all submodules; and to use the sum of the actual voltage of the submodule and the voltage difference as the state of charge of the submodule.

[0110] In one embodiment, the control module 1003 is further configured to determine the discrimination combination of the target sub-modules based on the discrimination difference and the rated discrimination of each sub-module; and to determine the target sub-modules in the target sequence based on the current direction and the discrimination combination.

[0111] In one embodiment, the control module 1003 is further configured to determine the deviation between the maximum actual voltage of the input submodule sequence and the minimum actual voltage of the cut-off submodule sequence; if the deviation is greater than a preset voltage equalization threshold, the first submodule corresponding to the maximum actual voltage of the input submodule sequence is switched to the cut-off state, and the second submodule in the cut-off submodule sequence with the same rated voltage as the first submodule and the minimum actual voltage is switched to the input state.

[0112] Each module in the bridge arm control device of the aforementioned hybrid converter valve can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of the hybrid converter valve system in hardware form or independent of it, or stored in the memory of the hybrid converter valve system in software form, so that the processor can call and execute the corresponding operations of each module.

[0113] In one exemplary embodiment, a hybrid converter valve system is provided, wherein the internal structure diagram of the controller in the hybrid converter valve system can be as follows: Figure 11 As shown, the hybrid converter valve system includes a controller, which comprises a processor, memory, input / output (I / O) interfaces, and a communication interface. The processor, memory, and I / O interfaces are connected via a system bus, and the communication interface is also connected to the system bus via the I / O interfaces. The processor provides computational and control capabilities. The controller's memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The controller's database stores control data. The controller's I / O interfaces are used for exchanging information between the processor and external devices. The controller's communication interface is used for communication with external terminals via a network connection. When the computer program is executed by the processor, it implements a bridge arm control method for the hybrid converter valve.

[0114] Those skilled in the art will understand that Figure 11 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the hybrid converter valve system to which the present application is applied. A specific hybrid converter valve system may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0115] In one exemplary embodiment, a hybrid converter valve system is provided, including a hybrid converter valve and a controller. The hybrid converter valve includes multiple bridge arms, each bridge arm including multiple sub-modules with at least two different rated voltages. The controller is connected to each sub-module and is used to implement the steps in the above embodiment of the bridge arm control method for the hybrid converter valve.

[0116] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps in the above-described embodiment of the bridge arm control method for a hybrid converter valve.

[0117] In one embodiment, a computer program product is provided, including a computer program that, when executed by a processor, implements the steps in the above-described embodiment of the bridge arm control method for a hybrid converter valve.

[0118] 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 computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, artificial intelligence (AI) processors, etc., and are not limited to these.

[0119] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0120] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. A bridge arm control method for a hybrid converter valve, characterized in that, The bridge arm comprises multiple sub-modules with at least two different rated voltages, and the method includes: Based on a preset voltage reference value, the required voltage of the bridge arm is converted into a required discrimination value, and the rated voltage of the submodule is converted into a rated discrimination value; The operational differentiation of the bridge arm is determined based on the rated differentiation of each of the sub-modules that are in the operational state; Based on the difference in discrimination between the already deployed discrimination and the required discrimination, the current direction of the bridge arm, and the rated discrimination of each submodule, a target submodule is determined in each submodule, and the operating state of the target submodule is switched; the operating state includes deployed state and disconnected state.

2. The method according to claim 1, characterized in that, The step of determining the target submodule among the submodules based on the difference between the already implemented discrimination and the required discrimination, the current direction of the bridge arm, and the rated discrimination of each submodule includes: The preset input sub-module sequence or the preset cut-off sub-module sequence is determined as the target sequence based on the discrimination difference. The target submodule is determined in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule.

3. The method according to claim 2, characterized in that, Before determining the preset input submodule sequence or the preset removal submodule sequence as the target sequence based on the discrimination difference, the method further includes: The state of charge of the submodule is determined based on its rated voltage and actual voltage. Based on the charge state of each submodule, the submodules in the input state and the submodules in the cut-off state are sorted to obtain a preset input submodule sequence and a preset cut-off submodule sequence.

4. The method according to claim 3, characterized in that, Determining the state of charge of the submodule based on its rated voltage and actual voltage includes: Determine the voltage difference between the rated voltage of the submodule and the maximum rated voltage among all submodules; The sum of the actual voltage of the submodule and the voltage difference is taken as the state of charge of the submodule.

5. The method according to claim 2, characterized in that, The step of determining the target submodule in the target sequence based on the discrimination difference, the current direction of the bridge arm, and the rated discrimination of each submodule includes: Based on the discrimination difference and the rated discrimination of each sub-module, the discrimination combination of the target sub-module is determined; Based on the combination of the current direction and the discrimination, a target sub-module is determined in the target sequence.

6. The method according to claim 3, characterized in that, After obtaining the preset input submodule sequence and the preset removal submodule sequence, the method further includes: Determine the deviation between the maximum actual voltage of the input submodule sequence and the minimum actual voltage of the cut-off submodule sequence; When the deviation value is greater than the preset equalization threshold, the first submodule corresponding to the maximum actual voltage of the input submodule sequence is switched to the cut-off state, and the second submodule in the cut-off submodule sequence with the same rated voltage as the first submodule and the smallest actual voltage is switched to the input state.

7. A bridge arm control device for a hybrid converter valve, characterized in that, The bridge arm includes multiple sub-modules with at least two different rated voltages, and the device includes: The conversion module is used to convert the required voltage of the bridge arm into the required discrimination value according to the preset voltage reference value, and to convert the rated voltage of the submodule into the rated discrimination value. The input module is used to determine the input differentiation of the bridge arm based on the rated differentiation of each of the sub-modules in the input state; The control module is used to determine the target submodule and the target switching state of the target submodule in each submodule based on the difference between the already implemented discrimination and the required discrimination, the current direction of the bridge arm and the rated discrimination of each submodule, and to control the target submodule based on the target switching state.

8. A hybrid converter valve system, characterized in that, The device includes a hybrid converter valve and a controller. The hybrid converter valve includes multiple bridge arms, each bridge arm including multiple sub-modules with at least two different rated voltages. The controller is connected to each of the sub-modules and is used to control the operating state of each of the sub-modules via the bridge arms of the hybrid converter valve according to any one of claims 1 to 6.

9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.

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