Active control is the process of applying loads to a wave energy converter (WEC), typically through the power take-off system, such that the WEC’s phase response is improved and power capture is increased. This technique has been studied extensively , particularly for single-body systems reacting against a fixed reference, and has shown potential for significant performance increases in controlled conditions . The application of active control to two-body, self-referenced WECs has received some attention, however, uncertainty about the achievable performance gains remains.
A class of WEC showing significant recent interest is the two-body flexibly-connected point absorber, examples shown in Figure 1. There are significant advantages to having a flexible tether connection between a surface float and a submerged reaction structure. These include greater simplicity of installation and reduction of structural cost, amongst others. Additionally, in the configuration used for Triton, the use of multiple tethers enables multi-mode energy capture. However, the application of active control techniques to flexibly-connected two-body WECs has received little to no attention in the literature.
The aim of this work is to evaluate different control strategies applied to a simple two-body single-tether architecture. The investigation will further attempt to tradeoff the benefits and feasibility of using control schemes relying on wave prediction techniques against causal methods. As a means of validating the identified strategies, these strategies will be tested and validated in the field using the single-tether MiniWEC test platform. Solutions for the single-tether system will then be adapted to the multiple-tether Triton WEC.