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; Zhou, Xiaoxin (IEEE Transactions on Power Systems, 2021)