SWINGO: Conceptualisation, modelling, and control of a swinging omnidirectional wave energy converter

Abstract

The vast majority of existing wave energy converter (WEC) technologies are designed to absorb wave power through a single mode of motion, often constraining the device on the remaining degrees-of-freedom (DoF) or neglecting their effects on the system dynamics and resulting power production. This paper introduces a novel multi DoF WEC designed to harvest wave power through the mechanical coupling of a gyropendulum system, parametrically excited by a moored floater. The gyropendulum mechanism is a hybrid technology that can incorporate, in a single body, the properties of both pendulum and gyroscope mechanics, ensuring effective energy harvesting in virtually every operational condition, i.e. making it suitable for multidirectional sea wave scatters. The gyropendulum versatility is enhanced during intermediate wave directions, in which both pitch and roll rotation are induced on the floater, prompting both gyroscopic effects, and the elasticity reaction forces on the mechanism. Relaying on such properties, the swinging omnidirectional (SWINGO) device can absorb wave power independently from the excited DoF, and therefore guaranteeing energy extraction independently of the incoming wave direction. System analysis and dynamic properties of the SWINGO system are computed by performing sensitivity studies, through the variation of both geometric properties and control conditions of the gyropendulum mechanism. For these purposes, we apply impedance-matching theory to explore the dynamic characteristics of the system under controlled conditions, and its performance in terms of power, making explicit emphasis in its main characteristics.