Date of Award
Master of Science in Electrical Engineering (MSEE)
Dr. Addy Wahyudie
Dr. Husain Shareef
Dr. Marcus Mueller
This thesis concerned with developing control strategies for a heaving sea wave Energy converter. The objective of this study is to improve captured and converted. Power. In heaving wave energy converters using a robust hierarchical control strategy. This strategy consists of higher and lower hierarchical controller. The higher controller provide a reference velocity signal, whereas the lower one follows the reference despite the uncertainties in the model. In this thesis, two novel methods for the higher controller are proposed. The objective of the first method is to design the intrinsic resistance that maximizes the captured power while considering the constraint on the elevation of the buoy. For this purpose, a constrained optimization quadratic problem is formulated as a function of the wave's significant height and peak frequency. The objective of the second method is to maximize the captured power without exceeding the allowable Level of the control force and a power take-off utilization index. Similarly, three novel lower hierarchical controller are proposed. The first method contain the P I D (proportional -integral-derivative) augmentation with sliding mode control. This method has an interesting feature in which the dynamic model in the lower level not needed. Hence, it can be categorized as a model-free controller. The PID handles the stability and speed of the convergence error, while the robustness and tracking properties are conducted by the sliding mode control. The second method proposes a robust PID controller, which is designed using complex polynomial stabilization. The last method proposes a novel lead-lag compensator, which is designed using Hoo theory with the objectives of maximizing the robustness and tracking properties while minimizing the control force of the power take-off device. The proposed method are methods using nominal and perturbation cases in regular and irregular sea states. The resultant performance under different perturbation scenarios is compared with existing control technique.
Mohamed Saeed, Omsalama Mubarak, "Hierarchical control strategies for heaving wave Energy converters" (2015). Theses. 91.