Switched Model and Dynamic Analysis of a Hydroturbine Governing System in the Process of Load Rejection Transient

Abstract

In this paper, we pay attention to studying the switched model of the hydroturbine governing system (HTGS) by introducing the concept of the switching of operational conditions. More specifically, utilizing the data of an existent hydropower station in China, we propose six nonlinear dynamic transfer coefficients of the hydroturbine, which can better describe the dynamic characteristics of the HTGS in the process of load rejection transient. Moreover, the elastic water hammer-impact of the penstock system and the nonlinearity of the generator for the process of load rejection transient are considered. Based on the combination of the different regulation modes of the governor and the corresponding running conditions of the hydroelectric generating unit, a novel nonlinear dynamic switched mathematical model of the HTGS is finally established. Meanwhile, the nonlinear dynamic behaviors of the governing system are exhaustively investigated using numerical simulations. These methods and analytical results will provide some theory bases for running a hydropower station.