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Parameter design and control method of hybrid modular multilevel converter

A modular multi-level and control method technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve the problem of limited improvement of the maximum modulation ratio of MMC and the inability to mix and modularize multiple The optimization of level converter parameters and operating characteristics and the limited influence of MMC operating characteristic optimization achieve the effects of reducing overall cost and volume, reducing the number of full-bridge sub-modules, and reducing capacitor voltage fluctuations

Active Publication Date: 2021-06-11
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1
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Problems solved by technology

However, the third harmonic injection method has limited improvement on the maximum modulation ratio of MMC, and has limited influence on the optimization of MMC operating characteristics.
[0005] Although the third harmonic injection and negative level utilization can both change the relationship between AC and DC voltage conversion in hybrid modular multilevel converters, most of the existing studies deal with the two methods separately, and it is impossible to synthesize the two methods. Advantages Optimize the parameters and operating characteristics of hybrid modular multilevel converters, and optimize the overall cost and volume

Method used

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  • Parameter design and control method of hybrid modular multilevel converter
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  • Parameter design and control method of hybrid modular multilevel converter

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Embodiment Construction

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

[0038] see figure 1 , figure 1 is a schematic diagram of the hybrid modular multilevel converter, such as figure 1 As shown, in the three-phase six bridge arms of the hybrid modular multilevel converter, each bridge arm contains N sub-modules, and each sub-module in the bridge arm contains N 0 Half-bridge sub-modules and K full-bridge sub-modules, the structure of which can be referred to as figure 2 Schematic diagram of the structure of the bridge arm of the h...

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Abstract

An embodiment of the invention discloses a parameter design and control method for a hybrid modular multilevel converter, which increases a modulation ratio of the hybrid modular multilevel converter to an optimal operation point through the coordination and cooperation of third harmonic voltage injection and a full-bridge sub-module negative level utilization method. The parameter design and control method comprises the steps of firstly, increasing the modulation ratio of the hybrid modular multilevel converter to the maximum extent through adopting a third harmonic voltage injection method, and secondly, increasing the modulation ratio to the optimal point through configuration of the cascade number of full-bridge sub-modules in bridge arms. When the hybrid modular multilevel converter outputs rated active power, the modulation ratio operates at an optimal operating point, so that a fundamental component of bridge arm power fluctuation can be changed into zero, the capacitance voltage fluctuation of the sub-module is greatly reduced, the capacitance use amount of the hybrid modular multilevel converter is greatly reduced, the number of required full-bridge sub-modules is reduced to the maximum extent, and the total cost and size of the device are reduced.

Description

technical field [0001] The invention relates to the technical field of voltage source converters and flexible direct current transmission, in particular to a parameter design and control method of a hybrid modular multilevel converter. Background technique [0002] Modular multilevel converter (English name is modular multilevel converter, referred to as MMC) has the advantages of easy realization of large number of levels, good harmonic performance, and modular design, and has become an inevitable choice for flexible DC transmission converters. . However, there is a large low-frequency power fluctuation on the MMC bridge arm, which will cause the voltage fluctuation of the sub-module capacitor. Therefore, it is necessary to design a large sub-module capacitance value to limit the voltage fluctuation within the allowable range. In existing projects, the volume ratio of the DC capacitor in the sub-module may reach more than 60%, and the cost ratio may reach more than 40%. T...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/219H02M7/483
CPCH02M7/219H02M7/483
Inventor 周月宾曹琬钰许树楷张楠朱喆
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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