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 hydrauli c turbine units, with penstock, spiral case and draft tube - is necessary d ue to power and frequency oscillations which normally occur in generator un its, mainly during load rejections. In turn, this causes large pressure and subpressure oscillations in turbine hydraulic system and it must be evalua ted to avoid mechanical failures. In this context, this work analyses the d iscrete hydraulic systems with emphasis on hydraulic parameter analysis. Th e simulation used was developed based on analog mathematical models of tran sient phenomenon equations and on a hydro turbine model. The results were o btained by using a nonlinear analog-digital simulation method. Comparisons between results of a theoretical simulation of a literature example using t he characteristics method and the results obtained with the present method are presented. Theoretical simulation results obtained from a 360 MW turbin e and experimental results are also confronted.