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Study of Sub-synchronous Resonance Oscillations in Wind Farms based on Variable Speed Wind Turbine Generators
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- Author / Creator
- Shi, Tong
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In recent years, wind farms (WFs) based on variable speed wind turbine generators (VSWTGs) are occupying a significantly increasing market share due to the capability of controlling wind energy generation. The power control system in VSWTGs improves the wind energy conversion efficiency, while makes VSWTGs more vulnerable to break. Sub-synchronous resonance (SSR) oscillations have been observed in WFs based on VSWTGs, causing significant damage and performance degradation. Therefore, a comprehensive study of SSR oscillations in VSWTGs is presented in this thesis. Related research in terms of SSR analysis methods, the mechanisms and influence factors analysis and existing mitigation methods is carried out to proposed improved SSR mitigation schemes.
The behind root causes of SSR oscillations in WFs based on type 3 and type 4 WTGs are commonly believed to be the series capacitor compensation network and the weak grid condition, respectively. Rather than focusing the external grid condition, in the thesis, the inherent impedance property of WFs is addressed. A comprehensive study is carried on based on the impedance model of VSWTGs to find the internal mechanisms and impact factors of SSR oscillations in WFs based on VSWTGs.
Although different mitigation methods of SSR oscillations have been proposed as a result of the many studies, there is not a detailed study which analyzed and compared these methods. Consequently, the investigation of alternative approaches to mitigate and to optimize the existing solutions becomes challenging. To fulfil this gap, a comprehensive evaluation of the SSR mitigation strategies has been presented in this dissertation. And improved SSR damping schemes for WFs based on VSWTGs are proposed. The identified improved approaches are presented along with the time and frequency domain simulation results to validate their effectiveness. -
- Graduation date
- Fall 2020
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.