Open Access

ARTICLE

A Dual Arm Complementary Hybrid Modulation Strategy Combining NL-SPWM for MMC Applications

by Mingwan Mei¹, Ping Wang¹, Yanbo Che^1,*, Zihan Lv¹, Zmarrak Wali Khanand¹, Chao Xing^1,2

1 Key Laboratory of Smart Grid of Ministry of Education, Tianjin University, Tianjin, 300072, China
2 Electric Power Research Institute of Yunnan Power Grid Co., Ltd., Kunming, 650217, China

* Corresponding Author: Yanbo Che. Email:

(This article belongs to the Special Issue: Advances in Modern Electric Power and Energy Systems)

Energy Engineering 2022, 119(2), 591-607. https://doi.org/10.32604/ee.2022.016585

Received 26 March 2021; Accepted 21 June 2021; Issue published 24 January 2022

Abstract

In the medium voltage direct current (MVDC) transmission system, a small number of MMC sub modules will reduce the power quality. In this paper, based on the research background of Photovoltaic Medium Voltage Direct Current (PV-MVDC) system, a Hybrid Modulation Strategy based on the Decoupled Double Synchronous Reference Frame (DDSRF) control strategy is proposed. The dual arm complementary hybrid modulation combining nearest-level-SPWM (NL-SPWM) can keep the number of SMs in the ON state constant. Then, the corresponding voltage sharing control algorithm of sub module (SM) is introduced. Through theoretical calculation, the modulation strategy can be found to stabilize the DC voltage and reduce the harmonic content. A 32-level MMC system has been developed to verity that the proposed hybrid modulation strategy and its SM voltage sharing algorithm have the advantages of restraining circulating current and maintaining capacitor voltage balance.

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Keywords

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