Method and device for controlling switching frequencies of MMC sub-modules and MMC

Abstract

The invention relates to a method and device for controlling the switching frequencies of MMC sub-modules and a MMC. When the sub-modules are controlled by using a retention factor sorting method, a switching frequency retention factor corresponding to a required switching frequency is obtained according to a correspondence relationship between the required switching frequency and the switching frequencies of the sub-modules and the switching frequency retention factor, and the correspondence relationship includes at least two sub-module switching frequencies and switching frequency retentionfactors corresponding to the switching frequencies of the sub-modules. Finally, the sub-modules are controlled by using the retention factor sorting method according to the switching frequency retention factor corresponding to the required switching frequency. The switching frequencies of the MMC sub-modules can be accurately controlled through the switching frequency control method.

Description

technical field [0001] The invention relates to a method and device for controlling switching frequency of an MMC sub-module and an MMC, belonging to the technical field of flexible power transmission and distribution of electric power systems. Background technique [0002] With the development of fully-controlled power electronic devices and the application of power electronics technology in power systems, the Voltage-Sourced Converter High Voltage Direct Current (VSC-HVDC) technology based on voltage source converters has attracted increasing attention. Modular Multilevel Converter (MMC, Modular Multilevel Converter) is a kind of voltage source converter in the application of flexible direct current transmission system. It is widely used in flexible direct current transmission and new energy access systems due to its remarkable advantages. [0003] The MMC-HVDC project must be tested before it is put into operation. However, the number of internal sub-modules is huge and t...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method for controlling the switching frequency of MMC sub-modules, which is used to solve the problem that the existing sorting voltage equalization algorithm for maintaining factors cannot accurately control the switching frequency of MMC sub-modules

The present invention also provides a switching frequency control device for MMC sub-modules, which is used to solve the problem that the existing sorting voltage equalization algorithm for maintaining factors cannot accurately control the switching frequency of MMC sub-modules

The present invention also provides an MMC, which is used to solve the problem that the sorting and equalizing algorithm of the maintenance factor in the existing MMC cannot realize precise control of the switching frequency of the MMC sub-module

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