Sub-synchronous oscillation analysis of transmission system with multiple wind farms

The sub-synchronous oscillation analysis of transmission system integrating multiple wind farms equipped with doubly-fed induction generator (DFIG) is discussed in this paper. The modeling of wind farm involving the shaft system, the DFIG and its control system as well as the mathematical models pertinent to the transmission line and load are derived, and the corresponding system state matrix is formed in accordance with eigenvalue analysis theory. Regarding a transmission system with multiple wind farms as an example, the impacts of the level and position of series compensated capacitor, the interaction between wind farms on modal frequency and damping ratio are elaborately investigated with some meaningful concluding remarks provided.