Damping of inter-area oscillations by combining control strategies in hydropower plants

Abstract

This paper examines how the damping capability can be improved if inter-area oscillations occur by combining control strategies in hydropower plants. First, the control challenges of hydropower plants, such as the water hammer effect, are discussed. In a single-machine infinite bus system (SMIBS), the use of a Power System Stabilizer (PSS) in the generator excitation and in the governor control path as well as the combination of both strategies are examined for their effectiveness in terms of their damping capability. In addition, these results are compared with an optimal state space controller with an observer as a damping element. The Heffron-Phillips model is the design model for the PSS as well as for the model-based controller. The verification of the damping capability through the PSS variants is evaluated by using a three-machine model in the time domain and by using modal analysis.