Control method and device for bridge arm hybrid sub-module of modular multilevel converter

Abstract

The invention discloses a control method and device for a hybrid sub-module of a bridge arm of a modular multi-level converter, and the method comprises the steps: enabling the bridge arm of the modular multi-level converter to comprise one or more sub-modules of working voltage types, obtaining a reference voltage of the bridge arm, and a preset working voltage and an actual operation voltage of each sub-module in the bridge arm; according to a preset adjustment rule, adjusting the value of the actual operation voltage of each sub-module to obtain the adjusted voltage of each sub-module; the preset adjustment rule is used for adjusting the value of the actual operation voltage of each sub-module to a unified reference; sorting the adjusted voltage of each sub-module to obtain a sorted sequence; and carrying out nearest level fitting by utilizing the sorting sequence, the preset working voltage of each sub-module and the reference voltage of the bridge arm to obtain the sub-module needing to be input in all the sub-modules. According to the invention, the problem of unbalanced voltage sharing among the hybrid sub-module groups can be avoided, and the control precision of the output voltage of the modular multilevel converter is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of modular multilevel converters, and in particular to a control method and device for a hybrid submodule of a bridge arm of a modular multilevel converter. Background Art

[0002] This section is intended to provide a background or context to the embodiments of the invention recited in the claims. No admission is made that the description herein is prior art by inclusion in this section.

[0003] At present, the flexible DC transmission system mainly adopts modular multi-level converters. For modular multi-level converters, the sub-modules of the bridge arm are generally of the same voltage level and the same type. With the development of higher voltage level switching devices such as IGBT (insulated gate bipolar transistor) and IGCT (integrated gate commutated thyristor) and the subsequent large-scale construction needs of flexible DC transmission system projects, it may face the situation of mixing sub-modules of different voltage levels in the same bridge arm of the converter valve. In the prior art, the research on the voltage balancing sorting algorithm of sub-modules in the bridge arm is relatively mature, but the research on the mixing of sub-modules of different voltage levels in the bridge arm is relatively small. For example, power modules composed of different types of power devices or power modules of different voltage levels are grouped, and an inter-group balancing control strategy is proposed to achieve voltage balance and switching frequency balance control between each group. However, this method is controlled by dividing modules and groups, which is prone to the problem of unbalanced voltage balancing between groups, resulting in an increasing difference between the actual output voltage and the desired target voltage, and a decrease in control accuracy. Summary of the invention

[0004] An embodiment of the present invention provides a control method for hybrid submodules of a bridge arm of a modular multilevel converter, which is used to avoid the problem of unbalanced voltage sharing between hybrid submodule groups and improve the control accuracy of the output voltage of the modular multilevel converter. In the method, the bridge arm of the modular multilevel converter includes submodules of one or more operating voltage types, and the method includes:

[0005] Obtaining the reference voltage of the bridge arm, the preset operating voltage of each submodule in the bridge arm, and the actual operating voltage;

[0006] According to a preset adjustment rule, the obtained value of the actual operating voltage of each submodule is adjusted to obtain the adjusted voltage of each submodule; the preset adjustment rule is used to adjust the value of the actual operating voltage of each submodule to a unified benchmark;

[0007] Sort the adjusted voltages of the submodules by magnitude to obtain a sorted sequence;

[0008] The nearest level fitting is performed using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodule that needs to be put into use among all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltages of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

[0009] The embodiment of the present invention further provides a control device for a hybrid submodule of a bridge arm of a modular multilevel converter, which is used to avoid the problem of unbalanced voltage sharing between groups and improve the control accuracy of the output voltage of the modular multilevel converter. The bridge arm of the modular multilevel converter in the device includes submodules of one or more working voltage types, and the device includes:

[0010] A data acquisition module is used to obtain the reference voltage of the bridge arm, the preset operating voltage of each submodule in the bridge arm, and the actual operating voltage;

[0011] A voltage processing module, used to adjust the obtained values ​​of the actual operating voltages of each submodule according to a preset adjustment rule to obtain the adjusted voltages of each submodule; the preset adjustment rule is used to adjust the values ​​of the actual operating voltages of each submodule to a unified benchmark;

[0012] A sorting processing module is used to sort the adjusted voltages of each submodule to obtain a sorting sequence;

[0013] The nearest level fitting processing module is used to perform nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodule that needs to be invested in all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltages of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

[0014] An embodiment of the present invention also provides a computer device, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the control method of the hybrid submodule of the bridge arm of the modular multilevel converter when executing the computer program.

[0015] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the control method of the hybrid sub-module of the bridge arm of the modular multi-level converter is implemented.

[0016] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the control method of the hybrid sub-module of the bridge arm of the modular multi-level converter is implemented.

[0017] In the embodiment of the present invention, the bridge arm is used as the overall control unit. After the capacitor voltage of each submodule of each working voltage type in the bridge arm is converted to a unified reference, all submodules in one bridge arm are uniformly sorted, avoiding the sorting disorder problem caused by directly sorting the capacitor voltage of submodules of different working voltage types in the same bridge arm. The obtained sorting sequence result reflects the deviation ratio of each submodule corresponding to its set working voltage, which can effectively ensure that the working voltage of each submodule of different voltage types works near their respective set values, avoiding the problem of multiple sorting controllers under the group sorting mode between different voltage submodules, and the problem of unbalanced voltage between groups. Finally, the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm are used to perform the nearest level fitting to obtain the submodules that need to be invested in all submodules, so that the deviation of the sum of the preset working voltages of the fitted submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement, which can effectively ensure the accuracy of the nearest level fitting and improve the control accuracy of the output voltage of the modular multi-level converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0019] Figure 1 Schematic diagram of a flow chart of a control method of a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention;

[0020] Figure 2 A specific example diagram of a control method for a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention;

[0021] Figure 3 FIG. 1 is another specific example diagram of a control method for a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention;

[0022] Figure 4 Schematic diagram of a control device for a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention;

[0023] Figure 5 Schematic diagram of a computer device in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] To make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the exemplary embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention.

[0025] The acquisition, transmission, storage, use, and processing of data in the technical solution of this application comply with the relevant provisions of national laws and regulations.

[0026] Figure 1 FIG. 1 is a flow chart of a control method of a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0027] Step 101, obtaining a reference voltage of a bridge arm, a preset operating voltage of each submodule in the bridge arm, and an actual operating voltage;

[0028] Step 102: adjusting the obtained values ​​of the actual operating voltages of the submodules according to preset adjustment rules to obtain the adjusted voltages of the submodules; the preset adjustment rules are used to adjust the values ​​of the actual operating voltages of the submodules to a unified reference;

[0029] Step 103, sorting the adjusted voltages of the submodules to obtain a sorting sequence;

[0030] Step 104, performing nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodule that needs to be put into use among all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltages of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

[0031] The control method of the hybrid sub-module of the bridge arm of the modular multi-level converter according to the embodiment of the present invention is explained in detail below.

[0032] The bridge arm of the modular multilevel converter in the embodiment of the present invention includes submodules of one or more operating voltage types.

[0033] In one embodiment, the working voltage type may be classified by voltage magnitude and may include different voltage magnitude levels, such as 2 kV, 3 kV, etc.

[0034] In the embodiment of the present invention, the bridge arm includes Z submodules with preset working voltages, where Z is a positive integer greater than or equal to 1;

[0035] The number of bridge arms of the converter including Z preset working voltages is M, where M is a positive integer greater than or equal to 1 and less than or equal to the total number of bridge arms in the converter.

[0036] During implementation, the reference voltage of the bridge arm, the preset operating voltage of each submodule in the bridge arm, and the actual operating voltage are obtained.

[0037] For example, the real-time working voltage of each submodule, that is, the specific value of the actual operating voltage, and the specific value of the preset working voltage value of each submodule are obtained through the control system of each submodule.

[0038] Then, according to the preset adjustment rules, the obtained values ​​of the actual operating voltages of each submodule are adjusted to obtain the adjusted voltages of each submodule; the preset adjustment rules are used to adjust the values ​​of the actual operating voltages of each submodule to a unified benchmark.

[0039] In one embodiment, the obtained actual operating voltage values ​​of each submodule are adjusted according to preset adjustment rules to obtain the adjusted voltages of each submodule, which may include: for each submodule, taking the ratio of the actual operating voltage value to the preset operating voltage value as the per-unit value of the submodule operating voltage.

[0040] Afterwards, the per-unit values ​​of the operating voltages of the submodules are sorted to obtain a sorted sequence.

[0041] For example, there are two sub-modules with two working voltages in the bridge arm, and their operating working voltages are 2kV and 3kV respectively. The actual working voltage of the 2kV sub-module can be divided by 2, and the actual working voltage of the 3kV sub-module can be divided by 3 to obtain the per-unit values ​​of the actual working voltages of all sub-modules in the bridge arm, and the per-unit values ​​of the working voltages of all sub-modules in the bridge arm can be uniformly sorted.

[0042] Figure 2 FIG. 1 is a specific example diagram of a control method of a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention. Figure 2 As shown, according to the preset adjustment rules, the obtained values ​​of the actual operating voltages of the submodules are adjusted to obtain the adjusted voltages of the submodules, which may include:

[0043] Step 201: Determine the adjustment ratio of each submodule according to the value of the preset working voltage of each submodule; the adjustment ratio is used to adjust the value of the actual operating voltage of each submodule to the same voltage reference level according to the respective adjustment ratios; the voltage reference level includes a voltage value within a set range;

[0044] Step 202: Adjust the actual operating voltage value of each submodule according to the adjustment ratio of each submodule.

[0045] In this example, the actual operating voltages of submodules of different operating voltage types are converted to a unified calculation benchmark. For example, if there are submodules with two operating voltages in the bridge arm, and their operating voltages are 2kV and 3kV respectively, the actual operating voltage of the 3kV submodule can be divided by 1.5 and sorted uniformly with the 2kV submodule.

[0046] In one embodiment, the capacitor voltages of the submodules under different operating voltage types are sorted using per-unit values, and the submodules of different voltage types are sorted using a unified scalar value. The obtained sorting results reflect the deviation ratio of each submodule with respect to its preset operating voltage, ensuring that each different voltage submodule operates near its own set operating voltage.

[0047] When sorting the adjusted voltages of the submodules, a sorting algorithm that reduces the switching frequency may be used.

[0048] Finally, the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm are used to perform the nearest level fitting to obtain the submodule that needs to be put into use among all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltages of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

[0049] Figure 3 FIG. 1 is another specific example of a control method for a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention. Figure 3 As shown, the method includes:

[0050] Step 301: obtaining the preset working voltage and the actual operating voltage of the submodules under each working voltage type in the bridge arm, and adjusting the actual operating voltage of each submodule to a unified reference, to obtain the voltage of each submodule after the unified reference;

[0051] Step 302: sorting the voltages of all submodules in the bridge arm after being unified with a reference, and obtaining the sorting of the voltages of the submodules after being unified with a reference under different working voltage types;

[0052] Step 303, obtain the reference voltage of the bridge arm, and perform nearest level fitting on the reference voltage of the bridge arm by sorting the voltages of the submodules under different working voltage types after unified reference and the preset working voltages of the submodules under different working voltage types, so as to obtain the submodules to be invested in the submodules under different working voltage types.

[0053] In step 301, the submodule to be put into operation needs to be determined in combination with the positive or negative reference voltage of the bridge arm and the direction of the bridge arm current.

[0054] In one embodiment, performing nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be invested in all the submodules may include:

[0055] When the reference voltage of the bridge arm is greater than or equal to zero, and the bridge arm current is in the submodule charging direction:

[0056] According to the adjusted voltage in the sorting sequence, the number of corresponding submodules put into use is accumulated one by one from zero, and the preset working voltage of the submodules to be put into use is accumulated from zero synchronously as the output voltage of the bridge arm;

[0057] When the absolute value of the deviation between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage in the sorting sequence is obtained, and the number of corresponding sub-modules put into operation is accumulated one by one from zero in order from small to large, and the sub-module corresponding to the result is put into operation, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0058] For example, when the reference voltage of the bridge arm is greater than or equal to zero, and the current of the bridge arm is in the charging direction of the submodule, based on the result of the adjusted voltage sorting in the sorting sequence, combined with the preset working voltages of the submodules of different working voltage types, the number of corresponding submodules put into operation is accumulated one by one from zero in order from small to large, and the preset working voltages of the submodules to be put into operation are synchronously accumulated from zero as the output voltage of the bridge arm. When the absolute value of the deviation value between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than 50% of the set working voltage of the subsequent submodule to be accumulated, the accumulation is stopped, and the number of submodules to be put into operation in the bridge arm in order from small to large is synchronously obtained and put into operation, and the remaining submodules are in the exit state.

[0059] In one embodiment, performing nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be invested in all the submodules may include:

[0060] When the reference voltage of the bridge arm is greater than or equal to zero, and the bridge arm current is in the submodule discharge direction:

[0061] According to the adjusted voltage sorting in the sorting sequence, the number of corresponding submodules put into use is accumulated one by one from zero, and the preset working voltages of the submodules to be put into use are accumulated from zero synchronously as the output voltage of the bridge arm;

[0062] When the absolute value of the deviation between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of sub-modules put into use is accumulated one by one from zero in order from large to small, and the sub-module corresponding to the result is put into use, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0063] For example, when the reference voltage of the bridge arm is greater than or equal to zero, and the current of the bridge arm is in the discharge direction of the submodule, based on the result of the adjusted voltage sorting in the sorting sequence, combined with the preset working voltages of the submodules of different voltage types, the number of corresponding submodules put into operation is accumulated one by one from zero in the order from large to small after the adjusted voltage sorting, and the preset working voltages of the submodules to be put into operation are accumulated from zero synchronously as the output voltage of the bridge arm. When the absolute value of the deviation value between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than 50% of the set working voltage of the submodule to be accumulated subsequently, the accumulation is stopped, and the number of submodules to be put into operation in the bridge arm in the order from large to small is synchronously obtained and put into operation, and the remaining submodules are in the exit state.

[0064] In one embodiment, performing nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be invested in all the submodules may include:

[0065] When there is a submodule capable of outputting negative level in the bridge arm, and the reference voltage of the bridge arm is less than zero, and the current direction of the bridge arm is to charge the negative level submodule that is put into use:

[0066] According to the adjusted voltage sorting in the sorting sequence, the number of corresponding negative level submodules put into use is accumulated one by one from zero, and the preset working voltages of the negative level submodules that can be put into use are accumulated from zero as the output voltage of the bridge arm synchronously;

[0067] When the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of negative level sub-modules put into operation is accumulated one by one from zero in order from small to large, and the sub-module corresponding to the result is put into negative level, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0068] For example, for a sub-module that can output a negative level in the bridge arm and the reference voltage of the bridge arm is less than zero, when the bridge arm current charges the negative level sub-module that is put into operation, based on the result of the adjusted voltage sorting in the sorting sequence, combined with the preset working voltages of the sub-modules of different voltage types that can be put into operation at a negative level, the number of corresponding sub-modules put into operation is accumulated one by one from zero in the order of small to large according to the adjusted voltage sorting, and the preset working voltage of the sub-module to be put into operation is accumulated from zero as the output voltage of the bridge arm synchronously, and the accumulation is stopped when the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than 50% of the set working voltage of the sub-module to be accumulated subsequently, and the number of sub-modules to be put into operation in the sub-modules that can be put into operation at a negative level in the bridge arm is synchronously obtained in the order of small to large and they are put into operation at a negative level, and the remaining sub-modules are in an exit state.

[0069] In one embodiment, performing nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be invested in all the submodules may include:

[0070] When there is a submodule capable of outputting a negative level in the bridge arm, and the reference voltage of the bridge arm is less than zero, and the direction of the bridge arm current is the discharge of the negative level submodule that is put into operation:

[0071] According to the adjusted voltage sorting in the sorting sequence, the number of corresponding negative level submodules put into use is accumulated one by one from zero, and the preset working voltages of the negative level submodules that can be put into use are accumulated from zero as the output voltage of the bridge arm synchronously;

[0072] When the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of negative level sub-modules put into operation is accumulated one by one from zero in order from large to small, and the sub-module corresponding to the result is put into negative level, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0073] For example, for a submodule that can output a negative level in the bridge arm and the reference voltage of the bridge arm is less than zero, when the bridge arm current discharges the negative level submodule that is put into operation, based on the result of the adjusted voltage sorting in the sorting sequence, combined with the preset working voltages of the submodules of different voltage types that can be put into operation at a negative level, the number of corresponding submodules put into operation is accumulated one by one from zero in order from large to small according to the adjusted voltage sorting, and the preset working voltage of the submodule to be put into operation is accumulated from zero as the output voltage of the bridge arm synchronously, and the accumulation is stopped when the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than 50% of the set working voltage of the submodule to be accumulated subsequently, and the number of submodules to be put into operation in the submodules that can be put into operation at a negative level in the bridge arm is synchronously obtained in order from large to small and they are put into operation at a negative level, and the remaining submodules are in an exit state.

[0074] For example, if there are two submodules with two working voltages in the bridge arm, and their operating voltages are 2kV and 3kV respectively, and the reference voltage of the bridge arm is 3.1kV, when the bridge arm current is the submodule charging direction, and the set working voltages of the first three submodules in the bridge arm PU value sorted from small to large are all 2kV, then the first two submodules in the bridge arm PU value sorted from small to large are put into use, and the number of submodules required to be put into use is 2; if the set working voltages of the first two submodules in the bridge arm PU value sorted from small to large are 2kV and 3kV respectively, then the first submodule in the bridge arm PU value sorted from small to large is put into use, and the number of submodules required to be put into use is 1.

[0075] In summary, the embodiment of the present invention discloses a control method for a hybrid submodule of a bridge arm of a modular multilevel converter. By converting the capacitor voltages of the submodules of different voltages in the bridge arm to a unified reference, the bridge arm is used as an overall control unit to uniformly sort all the submodules in one bridge arm, thereby avoiding the disordered sorting problem caused by directly sorting the capacitor voltages of the submodules of different voltage types in the same bridge arm. The obtained sorting result reflects the deviation ratio of each submodule corresponding to its preset working voltage, which can effectively ensure that the working voltages of the submodules of different voltages are all working near their respective set values, thereby avoiding the problem of multiple sorting controllers and inter-group voltage balancing problems under the current group sorting method between submodules of different voltages. The embodiment of the present invention proposes a nearest level fitting method including submodules based on different working voltage types, which can make the deviation of the fitted voltage value and the reference voltage of the bridge arm less than 50% of the set working voltage of a submodule to be subsequently fitted and accumulated, thereby effectively ensuring the accuracy of the nearest level fitting and avoiding the problem of increased nearest level approximation fitting voltage deviation under the current group sorting and triggering between submodules of different voltages.

[0076] The embodiment of the present invention also provides a control device for a modular multilevel converter bridge arm hybrid submodule, as described in the following embodiment. Since the principle of solving the problem by the device is similar to the control method for a modular multilevel converter bridge arm hybrid submodule, the implementation of the device can refer to the implementation of the control method for a modular multilevel converter bridge arm hybrid submodule, and the repeated parts will not be repeated.

[0077] Figure 4 Schematic diagram of a control device for a hybrid submodule of a bridge arm of a modular multilevel converter according to an embodiment of the present invention. Figure 4 As shown, the device 400 includes:

[0078] The data acquisition module 401 is used to acquire the reference voltage of the bridge arm, the preset working voltage and the actual operating voltage of each submodule in the bridge arm;

[0079] The voltage processing module 402 is used to adjust the obtained values ​​of the actual operating voltages of each submodule according to a preset adjustment rule to obtain the adjusted voltages of each submodule; the preset adjustment rule is used to adjust the values ​​of the actual operating voltages of each submodule to a unified reference;

[0080] The sorting processing module 403 is used to sort the voltages adjusted by each submodule to obtain a sorting sequence;

[0081] The nearest level fitting processing module 404 is used to perform nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodule that needs to be invested in all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltage of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

[0082] In one embodiment, the operating voltage type includes different voltage levels.

[0083] In one embodiment, the voltage processing module 402 is specifically used for:

[0084] For each submodule, the ratio of the actual operating voltage value to the preset operating voltage value is used as the per unit value of the submodule operating voltage.

[0085] In one embodiment, the voltage processing module 402 is specifically used for:

[0086] According to the value of the preset working voltage of each submodule, the adjustment ratio of each submodule is determined; the adjustment ratio is used to adjust the value of the actual operating voltage of each submodule to the same voltage reference level according to the respective adjustment ratios; the voltage reference level includes a voltage value within a set range;

[0087] According to the adjustment ratio of each submodule, the value of the actual operating voltage of each submodule is adjusted.

[0088] In one embodiment, the nearest level fitting processing module 404 is specifically used for:

[0089] When the reference voltage of the bridge arm is greater than or equal to zero, and the bridge arm current is in the submodule charging direction:

[0090] According to the adjusted voltage in the sorting sequence, the number of corresponding submodules put into use is accumulated one by one from zero, and the preset working voltage of the submodules to be put into use is accumulated from zero synchronously as the output voltage of the bridge arm;

[0091] When the absolute value of the deviation between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage in the sorting sequence is obtained, and the number of corresponding sub-modules put into operation is accumulated one by one from zero in order from small to large, and the sub-module corresponding to the result is put into operation, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0092] In one embodiment, the nearest level fitting processing module 404 is specifically used for:

[0093] When the reference voltage of the bridge arm is greater than or equal to zero, and the bridge arm current is in the submodule discharge direction:

[0094] According to the adjusted voltage sorting in the sorting sequence, the number of corresponding submodules put into use is accumulated one by one from zero, and the preset working voltages of the submodules to be put into use are accumulated from zero synchronously as the output voltage of the bridge arm;

[0095] When the absolute value of the deviation between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of sub-modules put into use is accumulated one by one from zero in order from large to small, and the sub-module corresponding to the result is put into use, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0096] In one embodiment, the nearest level fitting processing module 404 is specifically used for:

[0097] When there is a submodule capable of outputting negative level in the bridge arm, and the reference voltage of the bridge arm is less than zero, and the current direction of the bridge arm is to charge the negative level submodule that is put into use:

[0098] According to the adjusted voltage sorting in the sorting sequence, the number of corresponding negative level submodules put into use is accumulated one by one from zero, and the preset working voltages of the negative level submodules that can be put into use are accumulated from zero as the output voltage of the bridge arm synchronously;

[0099] When the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of negative level sub-modules put into operation is accumulated one by one from zero in order from small to large, and the sub-module corresponding to the result is put into negative level, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0100] In one embodiment, the nearest level fitting processing module 404 is specifically used for:

[0101] When there is a submodule capable of outputting a negative level in the bridge arm, and the reference voltage of the bridge arm is less than zero, and the current direction of the bridge arm is to discharge the negative level submodule that is put into operation:

[0102] According to the adjusted voltage sorting in the sorting sequence, the number of corresponding negative level submodules put into use is accumulated one by one from zero, and the preset working voltages of the negative level submodules that can be put into use are accumulated from zero as the output voltage of the bridge arm synchronously;

[0103] When the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of negative level sub-modules put into operation is accumulated one by one from zero in order from large to small, and the sub-module corresponding to the result is put into negative level, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

[0104] Figure 5 Schematic diagram of a computer device in an embodiment of the present invention. Figure 5 As shown, an embodiment of the present invention further provides a computer device 500, including a processor 501, a memory 502, and a computer program 503 stored in the memory 502 and executable on the processor 501, wherein the processor 501 implements the control method of the hybrid submodule of the bridge arm of the modular multilevel converter when executing the computer program 503.

[0105] An embodiment of the present invention further provides a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the control method of the hybrid sub-module of the bridge arm of the modular multi-level converter is implemented.

[0106] An embodiment of the present invention further provides a computer program product, which includes a computer program. When the computer program is executed by a processor, the control method of the hybrid sub-module of the bridge arm of the modular multi-level converter is implemented.

[0107] In the embodiment of the present invention, the bridge arm is used as the overall control unit. After the capacitor voltage of each submodule of each working voltage type in the bridge arm is converted to a unified reference, all submodules in one bridge arm are uniformly sorted, thereby avoiding the disordered sorting problem caused by directly sorting the capacitor voltages of submodules of different working voltage types in the same bridge arm. The obtained sorting sequence result reflects the deviation ratio of each submodule corresponding to its set working voltage, which can effectively ensure that the working voltage of each submodule of different voltage types works near their respective set values, avoiding the problem of multiple sorting controllers under the group sorting mode between different voltage submodules, and the problem of unbalanced voltage between groups. Finally, the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm are used to perform the nearest level fitting to obtain the submodules that need to be invested in all submodules, so that the deviation of the sum of the preset working voltages of the fitted submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement, which can effectively ensure the accuracy of the nearest level fitting and improve the control accuracy of the output voltage of the modular multilevel converter.

[0108] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0109] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0110] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0111] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0112] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A control method for a hybrid submodule of a modular multilevel converter bridge arm, characterized in that: The bridge arm of the modular multilevel converter includes submodules of one or more operating voltage types, and the method includes: Obtaining the reference voltage of the bridge arm, the preset operating voltage of each submodule in the bridge arm, and the actual operating voltage; According to a preset adjustment rule, the obtained value of the actual operating voltage of each submodule is adjusted to obtain the adjusted voltage of each submodule; the preset adjustment rule is used to adjust the value of the actual operating voltage of each submodule to a unified benchmark; Sort the adjusted voltages of the submodules by magnitude to obtain a sorted sequence; The nearest level fitting is performed using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodule that needs to be put into use among all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltages of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

2. The method according to claim 1, characterized in that The operating voltage types include different voltage levels.

3. The method according to claim 1, characterized in that According to the preset adjustment rules, the obtained values ​​of the actual operating voltages of the submodules are adjusted to obtain the adjusted voltages of the submodules, including: For each submodule, the ratio of the actual operating voltage value to the preset operating voltage value is used as the per unit value of the submodule operating voltage.

4. The method according to claim 3, characterized in that According to the preset adjustment rules, the obtained values ​​of the actual operating voltages of the submodules are adjusted to obtain the adjusted voltages of the submodules, including: According to the value of the preset working voltage of each submodule, the adjustment ratio of each submodule is determined; the adjustment ratio is used to adjust the obtained values ​​of the actual operating voltage of each submodule to the same voltage reference level according to the respective adjustment ratios; the voltage reference level includes a voltage value within a set range; According to the adjustment ratio of each submodule, the obtained value of the actual operating voltage of each submodule is adjusted.

5. The method according to claim 1, characterized in that The nearest level fitting is performed using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be put into use among all the submodules, including: When the reference voltage of the bridge arm is greater than or equal to zero, and the bridge arm current is in the submodule charging direction: According to the adjusted voltage in the sorting sequence, the number of corresponding submodules put into use is accumulated one by one from zero, and the preset working voltage of the submodules to be put into use is accumulated from zero synchronously as the output voltage of the bridge arm; When the absolute value of the deviation between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage in the sorting sequence is obtained, and the corresponding number of sub-modules put into operation is accumulated one by one from zero in order from small to large, and the sub-module corresponding to the result is put into operation, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

6. The method according to claim 1, characterized in that The nearest level fitting is performed using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be put into use among all the submodules, including: When the reference voltage of the bridge arm is greater than or equal to zero, and the bridge arm current is in the submodule discharge direction: According to the order of the adjusted voltages in the sorting sequence from large to small, the number of corresponding submodules put into use is accumulated one by one from zero, and the preset working voltages of the submodules to be put into use are accumulated from zero synchronously as the output voltage of the bridge arm; When the absolute value of the deviation between the output voltage of the bridge arm and the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the result of accumulating the number of corresponding sub-modules put into operation from zero in the order from large to small after the adjusted voltage sorting in the sorting sequence is obtained, and the sub-module corresponding to the result is put into operation, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

7. The method according to claim 1, characterized in that The nearest level fitting is performed using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be put into use among all the submodules, including: When there is a submodule capable of outputting negative level in the bridge arm, and the reference voltage of the bridge arm is less than zero, and the current direction of the bridge arm is to charge the negative level submodule that is put into use: According to the adjusted voltage sorting in the sorting sequence, the number of corresponding negative level submodules put into use is accumulated one by one from zero, and the preset working voltages of the negative level submodules that can be put into use are accumulated from zero as the output voltage of the bridge arm synchronously; When the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of negative level sub-modules put into operation is accumulated one by one from zero in order from small to large, and the sub-module corresponding to the result is put into negative level, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

8. The method according to claim 1, characterized in that The nearest level fitting is performed using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodules to be put into use among all the submodules, including: When there is a submodule capable of outputting a negative level in the bridge arm, and the reference voltage of the bridge arm is less than zero, and the direction of the bridge arm current is the discharge of the negative level submodule that is put into operation: According to the adjusted voltage sorting in the sorting sequence, the number of corresponding negative level submodules put into use is accumulated one by one from zero, and the preset working voltages of the negative level submodules that can be put into use are accumulated from zero as the output voltage of the bridge arm synchronously; When the absolute value of the deviation between the output voltage of the bridge arm and the absolute value of the reference voltage of the bridge arm is less than the preset percentage of the preset working voltage of the subsequent sub-module to be accumulated, the accumulation is stopped, and the adjusted voltage sorting in the sorting sequence is obtained, and the corresponding number of negative level sub-modules put into operation is accumulated one by one from zero in order from large to small, and the sub-module corresponding to the result is put into negative level, and the remaining sub-modules are in the exit state; the preset percentage includes 50%.

9. A control device for a hybrid submodule of a modular multilevel converter bridge arm, characterized in that: The bridge arm of the modular multi-level converter includes submodules of one or more operating voltage types, and the device includes: A data acquisition module is used to obtain the reference voltage of the bridge arm, the preset operating voltage of each submodule in the bridge arm, and the actual operating voltage; A voltage processing module, used to adjust the obtained values ​​of the actual operating voltages of each submodule according to a preset adjustment rule to obtain the adjusted voltages of each submodule; the preset adjustment rule is used to adjust the values ​​of the actual operating voltages of each submodule to a unified benchmark; A sorting processing module is used to sort the adjusted voltages of each submodule to obtain a sorting sequence; The nearest level fitting processing module is used to perform nearest level fitting using the sorting sequence, the preset working voltage of each submodule and the reference voltage of the bridge arm to obtain the submodule that needs to be invested in all the submodules; the nearest level fitting adjusts the submodule combination so that the deviation between the sum of the preset working voltages of the submodule combination and the reference voltage of the bridge arm meets the preset deviation requirement.

10. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method according to any one of claims 1 to 8 is implemented.

11. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

12. A computer program product, characterized in that The computer program product comprises a computer program, and when the computer program is executed by a processor, the method according to any one of claims 1 to 8 is implemented.

Images