An auxiliary circuit enhancing the DC fault clearing capability of hybrid MMCs with low proportion of FB-SMs

Fang, Xiongfeng, Li, Gen, Chen, Canfeng, Xiong, Jian and Zhang, Kai 2022. An auxiliary circuit enhancing the DC fault clearing capability of hybrid MMCs with low proportion of FB-SMs. IEEE Transactions on Power Electronics 10.1109/TPEL.2022.3171552

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Abstract

The hybrid modular multilevel converter (HMMC) composed of half-bridge (HB) and full-bridge (FB) submodules (SMs) is an alternative to the FB-MMC with lower loss and cost. However, the HMMCs maximum reverse-biased voltage (RBV) is lower than the FB-MMC, so does the dc fault clearing capability (DCFCC). Reduced RBV will prolong the fault clearing time, especially when the dc side inductance is large. In this letter, an auxiliary circuit is proposed for HMMCs, which can change the fault current paths and enable both HB- and FB-SMs to participate in the fault clearing. Thus, the maximum RBV of the HMMC is increased to be equal to an FB-MMC. Moreover, the proportion of FB-SMs can be reduced. With the auxiliary circuit, the DCFCC of the HMMC is enhanced with the reduction of the power losses and semiconductor costs. Simulations and scaled-down experiments validate the proposed method.

Item Type:	Article
Date Type:	Published Online
Status:	In Press
Schools:	Engineering
Publisher:	Institute of Electrical and Electronics Engineers
ISSN:	0885-8993
Date of First Compliant Deposit:	7 June 2022
Last Modified:	07 Jun 2022 15:10
URI:	https://orca.cardiff.ac.uk/id/eprint/149921

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