Nonlinear modeling and dynamic analysis of a hydro-turbine governing system in the process of sudden load increase transient

•Six dynamic transfer coefficients are innovatively proposed.•A novel dynamic model of a hydro-turbine governing system is proposed.•Nonlinear dynamic behaviors of the governing system are studied.•Bifurcations are studied in the process of sudden load increase transient.

In order to study the nonlinear dynamic behaviors of a hydro-turbine governing system in the process of sudden load increase transient, we establish a novel nonlinear dynamic model of the hydro-turbine governing system which considers the elastic water-hammer model of the penstock and the second-order model of the generator. The six nonlinear dynamic transfer coefficients of the hydro-turbine are innovatively proposed by utilizing internal characteristics and analyzing the change laws of the characteristic parameters of the hydro-turbine governing system. Moreover, from the point of view of engineering, the nonlinear dynamic behaviors of the above system are exhaustively investigated based on bifurcation diagrams and time waveforms. More importantly, all of the above analyses supply theoretical basis for allowing a hydropower station to maintain a stable operation in the process of sudden load increase transient.