Analysis of Very Low Frequency Oscillations in Hydro-Dominant Power Systems Using Multi-Unit Modeling

This paper presents a dynamic analysis for very low frequency oscillations (VLFO) observed in the Colombian power grid in the 0.05-Hz range. Guidelines for the dynamic modeling of power plants with hydro coupling and their multi-unit formulation for frequency stability studies are developed. Associated models are used within simulations of the Colombian power system including its major power plants to show the possible origin of the VLFO. Conclusions and recommendations for control of hydro turbines in a multi-unit environment are developed from the modeling effort and simulation studies.