PID Control of the OWC Plant to Improve Ocean Wave Energy Capture

This paper suggests a simple approach to design a proportional-integral-derivative (PID) controller for regulating the turbine speed of the oscillation water column (OWC) system. The objective of PID controller is to achieve the maximum wave energy extraction from OWC. The first prerequisite for PID controller development is to reduce and linearize the OWC plant because the plant dynamics are highly complicated and nonlinear in nature. The reduced OWC plant model is therefore developed and compared to the nonlinear OWC plant model. Afterwards, the linear OWC plant model is derived and the closed loop transfer function of the OWC plant with the PID control is obtained which is followed by the determination of the unknown PID variables by pole placement. Simulations are performed to create an open and closed loop response of the linear OWC plant model to verify the performance of the PID controller. The efficiency of the PID controller on a JONSWAP irregular wave model for a nonlinear OWC plant is also validated. Lastly, for regulated and unregulated OWC plants, essential parameters such as turbine flow coefficient and turbine output power are evaluated. The PID controller functions very well for the nonlinear OWC model as well.