Design of a novel nonlinear robust H_∞ sliding mode controller for complex nonlinear hydro-turbine regulating system

A nonlinear robust sliding mode control (NRSMC) strategy is proposed for the complex, uncertain, and nonlinear hydro-turbine regulating system (HTRS), grounded in nonlinear differential geometric control theory. First, a comprehensive nonlinear mathematical model of the HTRS is established. Then, by employing dynamic regulation output feedback linearization, the system is accurately transformed into an equivalent linear model. A novel robust sliding mode controller based on state feedback is designed, enabling the construction of an NRSMC scheme with strong disturbance rejection capability. This approach overcomes the zero dynamics design bottleneck commonly encountered in existing nonlinear governor control methods, thereby offering a new robust control solution for HTRS. Numerical simulations demonstrate that the proposed NRSMC effectively enhances system damping, suppresses external disturbances, and significantly improves system stability, showing clear advantages over existing nonlinear controllers based on simplified turbine models.