Decentralized control for multi-terminal cascaded medium-voltage converters considering multiple crossovers

Chen, Jinlei, Wang, Sheng ORCID: https://orcid.org/0000-0002-2258-2633, Liang, Jun ORCID: https://orcid.org/0000-0001-7511-449X, Navaratne, Rukshan and Ming, Wenlong ORCID: https://orcid.org/0000-0003-1780-7292 2024. Decentralized control for multi-terminal cascaded medium-voltage converters considering multiple crossovers. IEEE Transactions on Power Delivery 39 (1) , pp. 467-478. 10.1109/TPWRD.2023.3268829

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Abstract

Decentralized control with multiple droop characteristics can significantly improve the accuracy of power flow in medium-voltage direct-current (MVdc) networks. However, multiple crossovers caused by different control characteristics can lead to the drifts of power and voltage and instability issues. When this type of control is implemented in the cascaded three-level neutral-point-clamped (C3L-NPC) converters, on one hand, the mechanism of such the power and voltage drifts was not investigated. On the other hand, power control accuracy, dc voltage balancing across submodules (SMs) and multiple crossovers should all be considered, which requires suitable control methods. To address the challenges, firstly, the mechanism behind the power and dc voltage drifts is analyzed. Secondly, a control scheme is presented to improve the power control accuracy and dc voltage balancing and concurrently, to avoid the multiple crossovers. This is achieved by suitable droop gain design and adding a secondary power compensator. The presented control scheme is verified in MATLAB/Simulink simulation and experimentally validated in a three-terminal MVdc testbed. Results show that the accuracy of steady-state power flow is improved by 15% due to the elimination of multiple crossovers, while the power accuracy at dynamics improved by 13% with the secondary power compensator

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Engineering
Publisher:	Institute of Electrical and Electronics Engineers
ISSN:	0885-8977
Date of First Compliant Deposit:	21 April 2023
Date of Acceptance:	28 March 2023
Last Modified:	26 Mar 2024 13:36
URI:	https://orca.cardiff.ac.uk/id/eprint/158987

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