Small-Signal stability analysis of MMC-HVDC system with saturated transformer

Transformer saturation has a significant impact on the stability of HVDC systems. While traditional research has primarily focused on LCC-HVDC systems, studies on MMC systems remain limited. Given the anticipated dominance of MMC technology in the future, it is crucial to understand the instability...

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Main Authors: Hanwen Wang, Yang Wang, Xianyong Xiao, Yunzhu Chen, Shupeng Li, Zhijun Er, Zhenbin Li
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:International Journal of Electrical Power & Energy Systems
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Online Access:http://www.sciencedirect.com/science/article/pii/S0142061525000493
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author Hanwen Wang
Yang Wang
Xianyong Xiao
Yunzhu Chen
Shupeng Li
Zhijun Er
Zhenbin Li
author_facet Hanwen Wang
Yang Wang
Xianyong Xiao
Yunzhu Chen
Shupeng Li
Zhijun Er
Zhenbin Li
author_sort Hanwen Wang
collection DOAJ
description Transformer saturation has a significant impact on the stability of HVDC systems. While traditional research has primarily focused on LCC-HVDC systems, studies on MMC systems remain limited. Given the anticipated dominance of MMC technology in the future, it is crucial to understand the instability risks MMC-HVDC systems face under transformer saturation. The key challenge lies in accurately modeling the harmonic coupling induced by the saturated transformer and analyzing its interaction with MMC-HVDC systems. To tackle this challenge, the harmonic state space (HSS) technique is employed in this paper to model the harmonic coupling in MMC-HVDC systems with saturated transformers. Initially, a saturable transformer model is developed, with the excitation curve fitted using a polynomial approach. This model is then interconnected with the MMC-HVDC system to establish a comprehensive HSS model for analysis. To facilitate the stability analysis, the HSS model is further transformed into a single-input–single-output impedance representation, enabling the effects of harmonic coupling to be observed through impedance curves. Finally, a Nyquist-based stability analysis is performed to explain why MMC-HVDC systems are more prone to instability under transformer saturation and to identify key factors contributing to this instability. Simulation and experimental results validate the theoretical analysis.
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issn 0142-0615
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publishDate 2025-05-01
publisher Elsevier
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series International Journal of Electrical Power & Energy Systems
spelling doaj-art-d3cc8d2a5e654aee8f26afff1638cee52025-08-20T02:07:16ZengElsevierInternational Journal of Electrical Power & Energy Systems0142-06152025-05-0116611049810.1016/j.ijepes.2025.110498Small-Signal stability analysis of MMC-HVDC system with saturated transformerHanwen Wang0Yang Wang1Xianyong Xiao2Yunzhu Chen3Shupeng Li4Zhijun Er5Zhenbin Li6College of Electrical Engineering, Sichuan University, Chengdu 610044 ChinaCollege of Electrical Engineering, Sichuan University, Chengdu 610044 ChinaCollege of Electrical Engineering, Sichuan University, Chengdu 610044 China; Corresponding author.College of Electrical Engineering, Sichuan University, Chengdu 610044 ChinaState Grid Tianjin Electric Power Company, Tianjin 300074 ChinaState Grid Tianjin Electric Power Company, Tianjin 300074 ChinaState Grid Tianjin Electric Power Company, Tianjin 300074 ChinaTransformer saturation has a significant impact on the stability of HVDC systems. While traditional research has primarily focused on LCC-HVDC systems, studies on MMC systems remain limited. Given the anticipated dominance of MMC technology in the future, it is crucial to understand the instability risks MMC-HVDC systems face under transformer saturation. The key challenge lies in accurately modeling the harmonic coupling induced by the saturated transformer and analyzing its interaction with MMC-HVDC systems. To tackle this challenge, the harmonic state space (HSS) technique is employed in this paper to model the harmonic coupling in MMC-HVDC systems with saturated transformers. Initially, a saturable transformer model is developed, with the excitation curve fitted using a polynomial approach. This model is then interconnected with the MMC-HVDC system to establish a comprehensive HSS model for analysis. To facilitate the stability analysis, the HSS model is further transformed into a single-input–single-output impedance representation, enabling the effects of harmonic coupling to be observed through impedance curves. Finally, a Nyquist-based stability analysis is performed to explain why MMC-HVDC systems are more prone to instability under transformer saturation and to identify key factors contributing to this instability. Simulation and experimental results validate the theoretical analysis.http://www.sciencedirect.com/science/article/pii/S0142061525000493MMC-HVDCTransformer saturationHarmonic state spaceSmall-signal stability
spellingShingle Hanwen Wang
Yang Wang
Xianyong Xiao
Yunzhu Chen
Shupeng Li
Zhijun Er
Zhenbin Li
Small-Signal stability analysis of MMC-HVDC system with saturated transformer
International Journal of Electrical Power & Energy Systems
MMC-HVDC
Transformer saturation
Harmonic state space
Small-signal stability
title Small-Signal stability analysis of MMC-HVDC system with saturated transformer
title_full Small-Signal stability analysis of MMC-HVDC system with saturated transformer
title_fullStr Small-Signal stability analysis of MMC-HVDC system with saturated transformer
title_full_unstemmed Small-Signal stability analysis of MMC-HVDC system with saturated transformer
title_short Small-Signal stability analysis of MMC-HVDC system with saturated transformer
title_sort small signal stability analysis of mmc hvdc system with saturated transformer
topic MMC-HVDC
Transformer saturation
Harmonic state space
Small-signal stability
url http://www.sciencedirect.com/science/article/pii/S0142061525000493
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AT yunzhuchen smallsignalstabilityanalysisofmmchvdcsystemwithsaturatedtransformer
AT shupengli smallsignalstabilityanalysisofmmchvdcsystemwithsaturatedtransformer
AT zhijuner smallsignalstabilityanalysisofmmchvdcsystemwithsaturatedtransformer
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