Fast nonsingular terminal sliding mode controller design for Francis turbine with electrohydraulic IGV an experimental investigation

Integration of intermittent wind and solar power systems causes increased grid instability and enhanced disturbances and nonlinearity in the power system. Hydro-turbine (HT) power system plays a significant role in grid stability with the capability of providing part-load-operation, fast startup, shut-down, and load-change. The HT power systems frequently experience parametric uncertainty and external disturbance due to imposed nonlinearity from mechanical, actuating, and power systems. Further, the nonlinearities are enhanced due to the connectivity of multiple power generation and consumer areas with grid-load change. For such challenging situations, implementing sophisticated nonlinear robust controllers remains a thrust area of research for the stable operation of a hydropower system. For the problem at hand, a fast-nonsingular-terminal-sliding-mode-controller (FNTSMC), utilizing the concept of terminal-sliding-mode-reaching-law (TSMRL), is proposed to simultaneously achieve precise tracking, finite-time convergence, and attenuation of the chattering phenomenon. To further enhance these performance objectives, a superior reaching law, called adaptive-terminal-sliding-mode-reaching-law (ATSMRL), has been used along with FNTSMC to design a more efficient controller. A laboratory-scale FT system with a low-cost electrohydraulic IGV-actuating system is indigenously developed, and the above-mentioned controllers are implemented in real practice. The ITAE obtained as 1.38 × 10 3 , 1.10 × 10 3 , and 0.86 × 10 3 Ws 2 for power error with FPID, TSMRL-FNTSMC, and ATSMRL-FNTSMC, respectively. The actuator position ITAE is obtained as 0.052, 0.045, and 0.036 ms 2 FPID, TSMRL-FNTSMC, and ATSMRL-FNTSMC, respectively. Further 0.27rads, 0.15rads, and 0.12rads for turbine speed error with FPID, TSMRL-FNTSMC, and ATSMRL-FNTSMC, respectively obtained. The control energy obtained by reported FPID, TSMRL-FNTSMC, and ATSMRL-FNTSMC is 4.56 × 10 2 , 7.08 × 10 2 , and 3.78 × 10 2 , respectively. Furthermore, comparison of the ATSMRL-TSMC with second order sliding mode controller (SOSMC) and barrier function based adaptive sliding mode controller (BFASMC) is also performed.