Modeling and dynamic response control for primary frequency regulation of hydro-turbine governing system with surge tank

This paper aims to study the modeling and dynamic response control for primary frequency regulation of hydro-turbine governing system with surge tank. Firstly, the index of dynamic response control for primary frequency regulation is selected and illustrated. Then, the sine wave assumption of water level oscillation in surge tank is proposed, and a novel simplified model for hydro-turbine governing system is obtained. Using the simplified model, the analytical expression for dynamic response of power output is derived. Finally, the concept for the domain of primary frequency regulation is proposed. The effects of influence factors on response performance of primary frequency regulation are analyzed. The results indicate that water level oscillation in surge tank can be assumed as a sine wave. The assumed sine oscillation describes the characteristics of the unsteady flow in headrace tunnel and surge tank. The analytical solution for dynamic response of power output obtained from the sine wave assumption is reasonable and has good accuracy. The dynamic response of power output is superposed by four independent subwaves. The response performance of primary frequency regulation can be quantitatively evaluated by domain of primary frequency regulation. The larger the domain of primary frequency regulation, the better the response performance.