Hrishikesh Nitin Khedkar and Uday Rajdeep Sakleshpur Lokesh Gowda presents their master’s thesis

Student: Hrishikesh Nitin Khedkar and Uday Rajdeep Sakleshpur Lokesh Gowda
Main Supervisor: Jonas Ringsberg, Xinyuan Shao and Hua-Dong Yao
Examiner: Jonas Ringsberg
Opponent: Carolina Ribeiro Da Silva Mangas Pereira

Abstract of thesis

Wave energy is one of the abundant renewable energy sources in nature. The technology to harness this wave energy is at technology readiness level TRL 7-8 (stage 4), i.e., single full-scale prototypes have been tested at sea according to the development steps defined by the European Marine Energy Centre. To commercialize this technology, it must move to stage 5, that is the testing of several units of pre-commercial machines, in other words an array of wave energy converters (WECs). This thesis focuses on C4, the heaving point absorber WEC developed with the specifications from CorPower Ocean, and how it should be arranged in wave parks to maximize the harnessing of wave energy.

While it is important to improve the efficiency of the WEC, such a system is better utilized in groups forming an array of WECs, hence it is important to study the behaviour of such array. One of the key challenges in modelling a WEC array (a.k.a. wave park) is the interaction effects between the WECs. Studies have shown that interaction effects between WECs are important to optimize the power output of the wave park. The aim of this thesis is to model two different WEC arrays of 16 WECs, grouped as 4x4 and 8x2 WECs, and study the interaction effects for different environmental conditions. The study investigates the characteristics of the two arrays by varying the distance between the WECs, variation of the damping coefficient of the power take off (PTO) system for different environmental conditions.

A coupled hydrodynamic and structural response analysis is carried out using the DNV software SESAM. The power absorbed for all simulated conditions are evaluated and a methodology is proposed for the preliminary design analysis of wave parks.

Through the interaction analysis it was found that the performance of the WEC depends on several parameters and therefore it is difficult to obtain one ideal solution for all the variables. One suitable strategy is to limit the variables based on the operating conditions, which results in the optimization of the array for specific installation sites. All these factors must be systematically included in preliminary design studies. Examining these behaviours is crucial to unlocking and optimizing the full potential of wave parks.