Analysis of offshore wave energy converters’ subsystems for improving reliability and efficiency

Researcher: Gianmaria Giannini

Short term mission (STSM)

The recent advancement of micro-controllers and sensors, and the reduction of their costs, will enormously facilitate the progress of wave energy technology to industrial success. Micro-controllers and sensors can be applied to monitor and control wave energy converters (WEC) subsystems and mechanisms for ensuring, with a degree of redundancy, safe, reliable and efficient operation at all times. However, till the present, the wave energy research concentrated, for the most, only on the control of the power-take-off system without giving much attention to the design, control and powering of all other subsystems, which in contrast will also be necessary for operation. Various technical challenges exist for the design and implementation of subsystems on a WEC, for example ensuring an internal source of constant low-voltage power at all times and in all circumstances. Considered the mentioned aspects, the main scope of the proposed STSM is to investigate offshore WECs’ requirements related to electronic subsystems, to preliminary assess power requirements, solutions for on-board low-voltage power production and energy storage. Furthermore, the STSM will allow building a collaborative research link between the host and home institutions, which have complementary expertise. Overall, the aims of the proposed STSM are:

• Facilitate the development of WECs models and prototypes that include their subsystems to be tested in wave tanks and at sea;
• Improve, safety and reliability of wave energy converters for operational and survival conditions;
• Begin strong international research collaboration between research teams of the host and home institutions;
• Improve the state-of-the-art on the design and modelling of WECs’ subsystems.

Overlong experience on research marine systems and controls of the Norwegian University of Science and Technology (NTNU) will highly benefit the candidate and its home research team. The STSM would allow speeding up the development of CECO and other WECs, which are being developed at the Hydraulics, Water Resources and Environment Division of the Faculty of Engineering of the University of Porto (Rosa-Santos, et al. 2019; Giannini, et al. 2020). To the present time, research work related to wave energy at the University of Porto mainly focused on numerical models of offshore and nearshore WECs, on coastal ocean models, capable of accurately predicting the wavefield within coastal areas, and experimental testing at the ocean basin. On the other side, wave energy projects at NTNU focused significantly on the development of electrical systems employing theoretical and experimental research, also with real scale prototypes deployed at sea, concentrating on both mechanical and electrical aspects. The proposed STSM could be a starting point for long-term collaboration, in particular, focusing on the development and testing of a simplified Matlab/Simulink or Python model that can allow analysing WECs’ subsystems power consumption and on-board power generation.

The STSM will directly benefit the hosting institution as the topic proposed is well integrated within the hosting team area of research, which is related to the development of marine technology (Zadeh et al. 2016; Reddy et al. 2019). Besides, the STSM will allow the beginning of possible long-term joint research, allowing contributions on numerical modelling and integration of WECs into the coastal environment (Ramos et al. 2018, Cabral et al., 2020) from the home research team.