Active Control Strategy for Wind Farm Systems to Prevent Sub/super-Synchronous Oscillations

In recent years, the sub/super- synchronous oscillations problem has emerged as an important operational risk in the large-scale wind power systems of China. Some practical solutions that are mainly based on the control parameters improvements of wind turbine generators have been taken to prevent the oscillations. However, due to the complex operation conditions and continuous development of wind power, these off-line measurements cannot completely eliminate the potential oscillations risks. This paper is to propose an on-line stability analysis and active control method for large-scale wind power systems to prevent the sub/super-synchronous oscillation. At first, two-input two-output (TITO) system model and multi-input multi-output (MIMO) system model are presented for wind farm system, as well as the corresponding stability analysis approach. Then, an active control strategy for wind farm systems to prevent oscillations are proposed, which contains system level control and farm level control. Finally, the effectiveness of the proposed method is verified by the detailed time-domain simulation of a multiple wind farms system defined based on actual wind power base in China.