Frequency Stability Analysis with Renewable Energy Integration: Assessing the Impact of Photovoltaics on Ultra-Low Frequency Oscillations

The rapid increase in renewable energy has lowered the overall inertia of power systems, creating challenges for frequency stability. To address this, this paper simplifies the MIMO model of renewable energy integration and develops a SISO model for ultra-low frequency oscillation analysis, reducing the system's order. The impact of photovoltaic (PV) generation on ultra-low frequency oscillations is investigated through vector margin analysis, demonstrating that PV integration positively contributes to suppressing such oscillations. A parameter tuning method for PV active controllers is proposed and validated using Kundur's two-area four-machine system.