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A mmc modulation method optimized for AC and DC voltage quality

A technology of AC and DC voltage and modulation method, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve problems such as non-existence, and reduce excessive voltage fluctuations, etc. The effect of high switching frequency and optimized AC or DC voltage quality

Active Publication Date: 2022-07-22
BEIJING SIFANG JIBAO AUTOMATION +2
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the voltage equalization is still performed by sorting during the entire modulation process, the problem of sub-module bypass exit caused by carrier phase shift no longer exists

Method used

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  • A mmc modulation method optimized for AC and DC voltage quality
  • A mmc modulation method optimized for AC and DC voltage quality
  • A mmc modulation method optimized for AC and DC voltage quality

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Embodiment Construction

[0062] Hereinafter, an MMC AC / DC voltage modulation method of the present invention will be described in detail with reference to the accompanying drawings and embodiments. The present invention combines the advantages of the two modulation methods in the prior art, and overcomes the disadvantages of the two control methods, and further proposes an optimized sorting modulation method, that is, on the basis of the traditional nearest level approximation, the The remainder part abandons the traditional rounding method, but selects the corresponding sub-module for PWM control, so that the precise output of the modulation can be achieved in one cycle, and the purpose of reducing the harmonic distortion rate is achieved. Since the voltage equalization is still carried out through the sequencing method in the whole modulation process, the problem of the bypass of the sub-module caused by the carrier phase shift no longer exists.

[0063] In addition, in order to prevent the power el...

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Abstract

Aiming at the MMC modulation method optimized for AC and DC voltage quality, this method solves the large fluctuation of the output voltage caused by the dead zone caused by the simultaneous switching of a large number of modules when the voltage is equalized by the double threshold voltage equalization algorithm; by adjusting the relative phase of the PWM carrier of the upper and lower bridge arms Switching between AC voltage quality optimization and optimization for DC voltage quality. The invention introduces a double threshold voltage equalization method, and uses two threshold values ​​to control the sequence output of the modules when the modulation output remains unchanged. When the maximum value of the module voltage deviation is greater than the preset single-module switching secondary threshold value, only one The switching of the modules reduces the excessive voltage fluctuation caused by the dead zone when multiple modules are switched at the same time. When the voltage deviation is greater than the preset first-level threshold for full-sequencing switching, the full-sequencing switching is performed to reach the module level. The effect of controllable maximum voltage deviation.

Description

technical field [0001] The invention belongs to the field of direct current distribution network, and in particular relates to an MMC modulation method optimized for alternating current and direct current voltage quality. Background technique [0002] Modular multilevel converter (MMC) is the basic equipment that constitutes the DC distribution network. An accurate and effective modulation method is the basic condition for stable and efficient operation of MMC. There are two main modulation modes of MMC: Nearest Level Modulation (NLM) and Carrier PhaseShifting SPWM (CPS-SPWM). [0003] The recent level approximation modulation is mainly used for the voltage equalization control of large-scale sub-modules in flexible DC transmission. Due to the sufficient number of sub-modules, a good approximation effect can be achieved by adjusting the number of input sub-modules, and the power quality of AC and DC voltage and current can be achieved. It can meet the requirements, that is,...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483H02M7/5387H02M7/5395
CPCH02M7/483H02M7/53871H02M7/5395
Inventor 王继慷王一马彦宾张浩李思刘树操丰梅梅红明王皆庆游涛王立超
Owner BEIJING SIFANG JIBAO AUTOMATION