1. introduction 2. The small-signal model of wind power grid-connected system 3. Source-grid Interaction of wind power grid-connected system 4. The equivalence method, propagation mechanism and observability and controllability metrics of wind farm 5. The impedance analysis method of wind turbines grid-connected system 6. Suppression method of source-grid interaction of wind power grid-connected system 7. On-line identification of wind turbine network interactions based on big data 8. Power Quality issues in wind farms