The Impact of Supplementary Active Power Control of Wind Turbine on Power System Low-Frequency Oscillations

The supplementary active power control (SAPC) that is integrated into wind turbines has been widely used for improving the frequency stability of power systems with high penetration of wind energy. As power electronic control schemes play key roles in future power systems, it is essential to study the impact of SAPC on system stability. This paper presents a thorough methodology for the analysis of the SAPC on the low-frequency oscillatory stability of modern power systems. Firstly, the mathematical model that drives the dynamic interaction between the synchronous generators and the wind turbine is presented, by using that, the impact of the SAPC on the oscillatory stability is analyzed. After that, the impact of the SAPC on the oscillatory stability is demonstrated by nonlinear simulations using a simplified two-area system and IEEE 39-bus system. The simulations are executed with the consideration of the uncertainty of the operational conditions and the different levels of the penetration of wind farms, and the system's robustness has been also confirmed in the event of large disturbances. The simulation results show that the SAPC has significant impacts on low-frequency oscillatory stability. The methodology is a powerful tool for low-frequency oscillation analysis and damping controller design in the power system with high penetration of wind energy.