Modular multi-level converter configuration method and modulation strategy thereof

Abstract

The invention discloses a modular multi-level converter configuration method and a modulation strategy thereof. Aiming at the problems of too many sub-modules in HVDC distribution network, the technical scheme adopted by the invention is as follows: a modular multilevel converter includes different level sub-modules, the high-level sub-module adopts IGBT which can withstand high voltage level, andthe rated voltage of the high-level sub-module is Uc1. Assuming the DC inter-pole voltage is Udc, the number of the high-level sub-modules N1 and the rated voltage of the low-level sub-modules of each bridge arm are calculated without considering the redundancy of the sub-modules. Modular multi-level converter modulation strategy with different level sub-modules adopts nearest-neighbor approximation strategy, and high-level sub-modules and low-level sub-modules adopt complementary differentiation method. The invention can reduce the total number of sub-modules, thereby reducing the investmentcost of the MMC and reducing the occupied area of the MMC on the premise of meeting the system requirements, especially the harmonic requirements.

Description

technical field [0001] The invention belongs to the field of flexible direct current transmission and distribution control, and in particular relates to a configuration method of a modular multilevel converter including sub-modules of different levels and a modulation strategy thereof. Background technique [0002] With the development of flexible DC technology and the further maturity of the manufacturing process of electric power devices, the application of flexible DC in distribution networks is becoming more and more popular. Compared with the two-level converter, the modular multilevel converter (MMC) has the advantages of simple manufacturing process and excellent operating performance. When MMC is applied to the DC distribution network, due to the low voltage of the AC and DC system, if the IGBT uses the existing high-voltage devices, only a few sub-modules for each bridge arm in the MMC can be satisfied. [0003] However, when the number of bridge arm sub-modules is...

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem that the number of sub-modules of the DC distribution network is too large, the present invention provides an MMC configuration method with sub-modules of different levels and its modulation strategy. Optimized configuration of the number of modules, coupled with a suitable modulation strategy, can meet the requirements of system operation while reducing the number of sub-modules and investment costs

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