Ultra-Low Frequency Oscillation Damping Control Method for Hydro-Photovoltaic Integrated Systems

In recent years, ultra-low frequency oscillations (ULFOs) have occurred in power systems with a high proportion of hydropower, which seriously threatens the system stability. With the rapid increase of the proportion of photovoltaic (PV) plants in the power grid, it is feasible to use the regulation ability of PV plants to suppress ULFOs. First, the inadaptability of the traditional Phillips–Heffron model in the analysis of ULFOs is pointed out. Second, a frequency response model of hydro-PV integrated systems is established, and a PV supplementary damping control method for suppressing ULFOs is proposed on the basis of this model. Third, the frequency response model is extended to multihydropower and multi-PV systems, and the supplementary damping control parameters of multiple PV plants are designed collaboratively. Finally, time-domain simulation and experimental results validate the effectiveness of the proposed method.