Simple Controllers forWave Energy Devices Compared

The design of controllers for wave energy devices has evolved from early monochromatic impedance-matching methods to complex numerical algorithms that can handle panchromatic seas, constraints, and nonlinearity. However, the potential high performance of such numerical controller comes at a computational cost, with some algorithms struggling to implement in real-time, and issues surround convergence of numerical optimisers. Within the broader area of control engineering, practitioners have always displayed a fondness for simple and intuitive controllers, as evidenced by the continued popularity of the ubiquitous PID controller.Recently, a number of energy-maximising wave energy controllers have been developed based on relatively simple strategies, stemming from the fundamentals behind impedance-matching. This paper documents this set of (5) controllers, which have been developed over the period 2010?2020, and compares and contrasts their characteristics, in terms of energy-maximising performance,the handling of physical constraints, and computational complexity. The comparison is carried out both analytically and numerically, including a detailed case study, when considering a state-of-the-art CorPower-like device.Fil: García Violini, Diego Demián. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Faedo, Nicolás Ezequiel. Politecnico di Torino; ItaliaFil: Jaramillo Lopez, Fernando. Maynooth University; IrlandaFil: Ringwood, John V.. Maynooth University; Irland

A Broadband Time-Varying Energy Maximising Control for Wave Energy Systems (LiTe-Con+): Framework and Experimental Assessment

Motion of wave energy converters (WECs) is usually exaggerated as a consequence of the application of control strategies for energy absorption maximisation. With the aim of preserving the physical integrity of the devices, constraint handling mechanisms, as part of the underlying control strategies, are considered a key component. Recent developments in wave energy control include a linear time-invariant-based controller presented in the literature as LiTe-Con, which provides a simple constraint handling mechanism. However, this handling method can lead to conservative performance in certain scenarios. To overcome such limitations, this study presents a time-varying methodology for an online adaptation of the constraint handling mechanism in LiTe-Con, while preserving its original simplicity and efficiency. Experimental assessment of the presented control methodology is provided in this study, using a broad range of operating conditions. Results show that the presented control strategy (LiTe-Con+) exceeds the performance achievable with the original LiTe-Con. Additionally, the benefits of LiTe-Con+, such as low computational demand, technical versatility, and impressive performance level are highlighted.Fil: García Violini, Diego Demián. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Quilmes. Departamento de Ciencia y Tecnología; Argentina. Maynooth University; IrlandaFil: Pena Sanchez, Yerai. Universidad del País Vasco; EspañaFil: Faedo, Nicolás Ezequiel. Politecnico di Torino; ItaliaFil: Ferri, Francesco. Aalborg University; DinamarcaFil: Ringwood, John V.. Maynooth University; Irland