Increasing Power Capture of Wave Energy Converters via Advanced control of the PowerTake-Off

The increase in the ability of a wave energy converter (WEC) to capture energy from waves is critical to ensuring the viability and cost effectiveness of wave energy power devices. WECs absorb wave power by applying a back force to oppose the forces that waves exert on the system. The back force is implemented by the systems Power Takeoff and is typically chosen via a constant damping value (resistive control). However, researchers are investigating the opportunity to increase power capture with a back force that varies in response to individual waves (advanced control). Several advanced control algorithms have been recently proposed. Across these algorithms, the level of validation varies from highly idealized numerical studies to preliminary tank tests. The challenges of practical implementation have not been fully explored. OPT proposes an investigation of the leading advanced control algorithms to compare their implementation requirements and increase in power above the baseline of resistive control. In tank tests, OPT has previously demonstrated a power increase from one advanced algorithm. This experience highlighted practical considerations that must be addressed, such as the effect of system friction and inefficiency or errors in the algorithm inputs. In Phase I, OPT will develop a realistic numerical implementation of a leading advanced control algorithm for comparison to the baseline, resistive control in order to perform parameter studies. From the study results, the algorithms will be compared based on the following metrics: increase in power beyond the baseline, ease of implementation, and low implementation cost. In addition to the trade study, Phase I will produce a plan for a wave tank test using a scale model of an OPT PowerBuoy with a working Power Takeoff in Phase II. The proposed work evaluates promising new methods to increase the power captured in realistic conditions by Wave Energy Converters. As such, it addresses the central obstacle to the commercial development of wave power, the cost of electricity. Reduction in the costs associated with the build, deployment and maintenance will accelerate the commercialization of wave powered systems.