Mitigating Ultra-Low-Frequency Oscillations in Wind-Penetrated Hydro-dominant Power Grid through Virtual Inertia Emulation Strategy

This paper aims to improve the frequency stability in wind penetrated hydro-dominant power grids. Such an environment is subjected to two significant technical challenges. On the one hand, the occurrence of ultra-low frequency oscillations leading to hydro-dominant power systems collapse, which has been frequently noticed in the two last decades. On the other hand, wind generators mainly present relatively low inertia, increasing bad frequency response (rate of change of frequency, frequency nadir) following disturbances. However, through virtual inertia control, variable speed wind turbines (VSWT) have demonstrated the ability to participate in frequency regulation of the power system by releasing the kinetic energy stored in the rotor for a time and increasing the active power output. In this paper, the ability of virtual inertia emulation from doubly fed induction generator-based wind turbines (DFIG-WT) to participate in the damping of hydro-dominant grid ultra-low frequency oscillations (ULFO) is investigated. The ultra-low frequency oscillations are successfully reproduced in the chosen test system. Then results are shown and discussed to validate the effectiveness of the proposed strategy.