Abstract: In recent years, with the increasing proportion of renewable energy such as wind and solar types in the energy supply, its intermittency and unpredictability have brought more challenges to the stability of power grids. Hydropower units, as important regulators in a power grid, are often equipped with governors that widely use traditional proportional-integral-derivative (PID) control. However, PID control has poor adaptability to complicated unit operating conditions; while sliding mode control, as an important robust control strategy, has great potential in achieving the optimal operation of hydropower units. This paper describes an improved sliding mode controller for the hydro-turbine regulating system, and analyzes the cause of the false stability phenomenon. We optimize the parameters of this controller based on the adaptive fuzzy particle swarm optimization (AFPSO) algorithm and the integrated time absolute error (ITAE) indicators, and verify its effectiveness through a case study of numerical simulations.

Key words: hydropower unit, sliding mode control, parameter optimization, false stability