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Main Authors: Sun, Qianhao, Meng, Jingwei, Li, Ruofan, Xia, Mingchao, Chen, Qifang, Zhou, Jiejie, Fan, Meiqi, Guo, Peiqian
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2502.05845
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author Sun, Qianhao
Meng, Jingwei
Li, Ruofan
Xia, Mingchao
Chen, Qifang
Zhou, Jiejie
Fan, Meiqi
Guo, Peiqian
author_facet Sun, Qianhao
Meng, Jingwei
Li, Ruofan
Xia, Mingchao
Chen, Qifang
Zhou, Jiejie
Fan, Meiqi
Guo, Peiqian
contents The modular multilevel converter (MMC) has become increasingly important in voltage-source converter-based high-voltage direct current (VSC-HVDC) systems. Direct and indirect modulation are widely used as mainstream modulation techniques in MMCs. However, due to the challenge of quantitatively evaluating the operation of different modulation schemes, the academic and industrial communities still hold differing opinions on their performance. To address this controversy, this paper employs the state-of-the-art computational methods and quantitative metrics to compare the performance among different modulation schemes. The findings indicate that direct modulation offers superior modulation potential for MMCs, highlighting its higher ac voltage output capability and broader linear PQ operation region. Conversely, indirect modulation is disadvantaged in linear modulation, which indicates inferior output voltage capability. Furthermore, this paper delves into the conditions whereby direct and indirect modulation techniques become equivalent in steady-state. The study findings suggest that the modulation capability of direct modulation is the same as that of indirect modulation in steady-state when additional controls, including closed-loop capacitor voltage control and circulating current suppression control (CCSC), are simultaneously active. Simulation and experiments verify the correctness and validity.
format Preprint
id arxiv_https___arxiv_org_abs_2502_05845
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Exploiting the Hidden Capacity of MMC Through Accurate Quantification of Modulation Indices
Sun, Qianhao
Meng, Jingwei
Li, Ruofan
Xia, Mingchao
Chen, Qifang
Zhou, Jiejie
Fan, Meiqi
Guo, Peiqian
Systems and Control
The modular multilevel converter (MMC) has become increasingly important in voltage-source converter-based high-voltage direct current (VSC-HVDC) systems. Direct and indirect modulation are widely used as mainstream modulation techniques in MMCs. However, due to the challenge of quantitatively evaluating the operation of different modulation schemes, the academic and industrial communities still hold differing opinions on their performance. To address this controversy, this paper employs the state-of-the-art computational methods and quantitative metrics to compare the performance among different modulation schemes. The findings indicate that direct modulation offers superior modulation potential for MMCs, highlighting its higher ac voltage output capability and broader linear PQ operation region. Conversely, indirect modulation is disadvantaged in linear modulation, which indicates inferior output voltage capability. Furthermore, this paper delves into the conditions whereby direct and indirect modulation techniques become equivalent in steady-state. The study findings suggest that the modulation capability of direct modulation is the same as that of indirect modulation in steady-state when additional controls, including closed-loop capacitor voltage control and circulating current suppression control (CCSC), are simultaneously active. Simulation and experiments verify the correctness and validity.
title Exploiting the Hidden Capacity of MMC Through Accurate Quantification of Modulation Indices
topic Systems and Control
url https://arxiv.org/abs/2502.05845