Robust Gain Scheduled Control of a Hydrokinetic Turbine

A vertical-axis hydrokinetic turbine speed control system is developed that guarantees stability and performance properties for the entire range of operation including tracking of the maximum power point below rated speeds and power regulation above rated speed. Secondary objectives include explicitly incorporating a tuning method to adjust the tradeoff between reference tracking and load transients and an advanced control methodology to attract industry acceptance. To facilitate this, an H_∞ linear parameter varying (LPV) controller was developed based on a physical model and iterative simulation-based testing. This paper outlines development of the turbine mathematical model, control objectives, control strategy, controller design as well as the results of simulation and field testing on a 5 kW hydrokinetic turbine. Results are compared to a fixed point PI controller tuned for reference tracking only.