TY  - SER
AU  - liu, Wei
AU  - Xie, Xiaorong
AU  - Shair, Jan
AU  - He, Jingbo
TI  - Frequency-Coupled Impedance Model-Based Sub-Synchronous Interaction Analysis  for  Direct-Drive Wind Turbines Connected to a Weak Ac Grid
KW  - Sub-Synchronous Osciliation (Sso)
KW  - Power Electronic Converters
KW  - Impedance-Based System
ER  -