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Low-frequency converter-driven oscillations in weak grids: explanation and damping improvement

Wu, Guanglu, Sun, Huadong, Zhao, Bing, Xu, Shiyun, Zhang, Xi, Egea-Alvarez, Agusti, Wang, Shanshan, Li, Gen, Li, Yingbiao and Zhou, Xiaoxin 2021. Low-frequency converter-driven oscillations in weak grids: explanation and damping improvement. IEEE Transactions on Power Systems 10.1109/TPWRS.2021.3099341

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Abstract

Low-frequency oscillations have been reported in several weak-grids-connected voltage-source-converter(VSC) systems. Although efforts have been devoted to understand the parametric and sensitivity impact of the VSC controller gains, a general formulation of the oscillation mechanism is still missing. Using transfer function dynamic modelling approach, we find that the outer loop active power control's bandwidth mainly determines the oscillation frequency. The PLL introduces a large phase lag around the frequency of the PLL bandwidth in weak grids conditions which decreases the oscillation damping. A simple but effective PI+Clegg integrator (CI) compensator is proposed to replace the standard outer loop active power controller compensating the PLL's phase delay and increase the oscillation damping. The results are verified in a real time digital simulator.

Item Type: Article
Date Type: Published Online
Status: In Press
Schools: Engineering
Publisher: Institute of Electrical and Electronics Engineers
ISSN: 0885-8950
Date of First Compliant Deposit: 13 September 2021
Date of Acceptance: 30 July 2021
Last Modified: 21 Oct 2021 07:27
URI: http://orca.cardiff.ac.uk/id/eprint/143982

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