Hydro power scheme models in interactive power system and governor studies
In this thesis a mathematical and computer model is formulated to accurately represent the behaviour of the hydraulic and mechanical systems in a hydro power plant. It includes the elastic behaviour of the hydraulic system and the actual operating characteristics of the hydromachines under consideration. After verifying the accuracy of this detailed hydraulic/mechanical model, frequency response tests are conducted to enable a comparison to be made with the IEEE transfer function model. This transfer function although widely used and accepted as a hydro power scheme model in power system and governor studies (1-5) does not represent waterhammer in the hydraulic system or the actual behaviour of the hydromachines. The frequency response tests which are reported in this thesis clearly highlight the severe practical limitations of this model at both low and high frequencies of governor operation. The frequency response results for the detailed hydraulic/mechanical model also enable improved linear transfer functions to be derived. Finally, with the aid of an existing power system stability computer program, the responses of the detailed hyrdaulic/mechanical model, the derived linear transfer function model and the IEEE transfer function model to variations in load are compared in the time domain.