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MMC (modular multilevel converter) harmonic circulating current restraining and direct-current power fluctuation restraining method

A DC power and fluctuation suppression technology, which is applied in the direction of irreversible DC power input conversion to AC power output, output power conversion device, electrical components, etc., can solve the problem of poor control effect of the controller

Active Publication Date: 2015-03-04
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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  • Abstract
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  • Claims
  • Application Information

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Problems solved by technology

The main advantage of this controller is that the control idea is simple and direct, and it is easy to implement; however, this controller must sample the bridge arm current of the MMC, and it can only be applied to a 3-phase MMC. Controller doesn't work well

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  • MMC (modular multilevel converter) harmonic circulating current restraining and direct-current power fluctuation restraining method
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  • MMC (modular multilevel converter) harmonic circulating current restraining and direct-current power fluctuation restraining method

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Embodiment Construction

[0034] The present invention will be further described below in combination with specific embodiments.

[0035] A harmonic circulation suppression and DC power fluctuation suppression method of MMC in the present invention includes two parts: a modulation link based on sub-module voltage estimation and a proportional control link based on DC current fluctuation feedback. The modulation link first estimates the sub-module voltage of each bridge arm , and then use a certain modulation technique to obtain the number of sub-modules expected to be invested in each bridge arm. The proportional control link corrects the number of sub-modules expected to be put into each bridge arm.

[0036] The method of the invention can effectively suppress the harmonic circulation of MMC. The proportional control link corrects the number of sub-modules expected to be invested in each bridge arm, which can not only further eliminate the circulation fluctuation caused by the estimation error, but a...

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Abstract

The invention discloses an MMC (modular multilevel converter) harmonic circulating current restraining and direct-current power fluctuation restraining method. The method includes a modulation link based on submodule voltage estimation and a proportional control link based on direct-current fluctuation feedback. According to the modulation link, submodule voltage of each bridge arm is firstly estimated, and then the number of submodules expected to be invested for each bridge arm is obtained by the aid of a certain modulation technology. According to the method, MMC harmonic circulating current can be effectively restrained, the number of the submodules expected to be invested for each bridge arm is modified in the proportional control link, circulating current fluctuation caused by estimation errors can be further eliminated, the internal circulating current of an MMC can be restrained, the internal equivalent damping of the MMC can be effectively increased, and the dynamic response characteristic of direct-current is improved. The method is used for restraining the MMC harmonic circulating current and direct-current power fluctuation, and an alternating-current system can reliably work and is fine in robustness when being normal or faulted. Besides, the method does not need to sample current of each bridge arm.

Description

technical field [0001] The invention relates to the application of power electronics technology and the field of power transmission and distribution in power systems, in particular to a method for suppressing harmonic circulation and direct current power fluctuation of an MMC (modular multilevel converter). Background technique [0002] Due to the use of fully controlled power electronic power devices (such as IGBT and IEGT) and pulse width modulation strategy, the flexible DC transmission technology with voltage source converter as the core has the advantages of independent control of active and reactive power and convenient power flow reversal. Compared with the conventional DC power transmission technology based on thyristors, flexible DC power transmission technology is easy to form multi-terminal DC power transmission, which can supply power to passive network systems (such as islands, offshore drilling platforms), and is especially suitable for new energy power generati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M1/12H02M1/32
CPCH02M1/14H02M7/49
Inventor 周月宾许树楷黎小林朱喆陈俊罗雨
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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