A nonlinear load frequency controller for hydropower plants

ABSTRACT An efficient way to generate power is the key requirement for hydropower plants. One can improve the overall efficiency of hydropower plants by using advanced turbine models, appropriate design of tunnel and water storage areas, by designing efficient control systems, etc. The ultimate aim of the governor or control systems is to maintain the load frequency at the desired or reference value during the nominal as well as uncertain conditions. Most of the present hydraulic-electrical control systems for hydropower plants are based on linearised models; wherein tedious tuning process is required to achieve the desired response. Furthermore, the linear control design may not work for wide range of operating points. In this paper, we propose a nonlinear controller and observer scheme using State-Dependent Riccati Equation (SDRE) methodology for hydropower plant to achieve the desired frequency in nominal and uncertain conditions. The proposed SDRE scheme is directly based on nonlinear hydropower plant models, wherein linearisation is not required. The effectiveness of the proposed SDRE scheme is validated on a nonlinear hydropower plant model and is compared with the conventional controller in the presence of noises and parametric uncertainties.