Analysis of Oscillations in Wind Farms Integrated into the Grid Through Flexible Direct Current Transmission Systems

As the share of renewable energy in the power supply grows, power system oscillations are escalating in severity. This paper analyzes the oscillation problem of a direct-drive wind farm connected to the power grid through a voltage source converter based high-voltage direct current transmission system (VSC-HVDC). First, a small signal model is constructed based on modular principles, and the eigenvalue analysis method is applied to solve the state matrix of the entire system to determine the oscillation mode in the system. Secondly, the main factors affecting the subsynchronous oscillations are investigated by the methods of participation factor analysis. Finally, the subsynchronous oscillation is suppressed by optimizing the parameters of the controller at the network side, and the correctness of the theoretical analysis and the effectiveness of the suppression strategy are verified by simulation.