Study of hydraulic transients in hydropower plants through simulation of nonlinear model of penstock and hydraulic turbine model

Study of hydraulic transients in hydropower plants specifically in hydraulic turbine units, with penstock, spiral case and draft tube-is necessary due to power and frequency oscillations which normally occur in generator units, mainly during load rejections. In turn, this causes large pressure and subpressure oscillations in turbine hydraulic systems and must be evaluated to avoid mechanical failures. In this context, this work analyses discrete hydraulic systems with emphasis on hydraulic parameter analysis. The simulation used was developed based on analog mathematical models of transient phenomenon equations and on a hydro turbine model. The results were obtained by using a nonlinear analog-digital simulation method. Comparisons between results of a theoretical simulation of a literature example using the characteristics method and the results obtained with the present method are presented. Theoretical simulation results obtained from a 360 MW turbine and experimental results are also confronted.