Spreadsheet which provides estimates of reductions in Levelized Cost of Energy for a surge-mode wave energy converter (WEC). This is made available via adoption of the advanced control strategies developed during this research effort.

Initial laboratory experiments with coordinated phase control of cross-flow turbines in a dense array.

The TidGen Power System generates emission-free electricity from tidal currents and connects directly into existing grids using smart grid technology. The power system consists of three major subsystems: shore-side power electronics, mooring system, and turbine generator unit (TGU) device. This submission includes a technical report on control system development, supporting simulations and supervisory control and data acquisition (SCADA) system requirements. Also included is the final design of the control and SCADA system, with supporting simulations and risk mitigation control strategies to address major system technical risks.

This project shows that the choice of a secondary DOF for survivability is a viable option to reduce the levelized cost of energy (LCOE) in WEC designs. This report will cover the calculation of the concluded LCOE advantage using Dehlsen Associates’ “Centipod” WEC, but will also discuss the entire project from start to finish, including mid and high-fidelity modeling, survival mode trade study, wave basin testing, and design tool cross-verification and validation.

The work aims to achieve optimal tidal energy conversion through a comprehensive approach of modeling, optimization, and control hardware-in-the-loop (CHIL) validation. By developing accurate models and employing optimization techniques, it seeks to identify efficient system configurations and control strategies. HIL validation will ensure the performance and reliability of the optimized tidal energy conversion system. The preparation of the present manual has been supported by the U.S. Department of Energy.

This dataset contains data recordings generated during Year 3 of a DOE-funded project focused on the co-design of marine energy converters and autonomous underwater vehicle (AUV) docking and recharging systems. Data was collected during experimental testing at the O.H. Hinsdale Wave Research Laboratory and support foundational research aimed at advancing coupled Wave Energy Converter (WEC)-AUV systems for marine energy applications. This release builds on and supplements data provided in the previously submitted Year 3 project software and data submission from this project, linked below. This dataset includes measurements of wave elevation, water pressure, dock motion, load on a dock, and load on a fixed Autonomous Underwater Vehicles (AUV). Additionally, a testing log is provided including testing logs and summary of the five conditions tested: -(1) regular and random waves -(2) waves with dock motions -(3) multi-sine waves -(4) multi-sine dock motions -(5) multi-sine waves with dock motions.

This submission includes three peer-reviewed (under review) papers from the researchers at North Carolina State University presenting different control-based techniques to maximize the efficiency and robustness of a tethered energy-harvesting kite. Below are the abstracts of each file included in the submission. Naik ACC - Geometric Structural Control Co-Design.pdf Focusing on a marine hydrokinetic energy application, this paper presents a combined geometric, structural, and control co-design framework for optimizing the performance of energy-harvesting kites subject to structural constraints. While energy-harvesting kites can offer more than an order of magnitude more power per unit of mass than traditional fixed turbines, they represent complex flying devices that demand robust, efficient flight controllers and are presented with significant structural loads that are larger with more efficient flight. Daniels IFAC - Optimal Cyclic Spooling Control.pdf This paper presents a control strategy for optimizing the the spooling speeds of tethered energy harvesting systems that generate energy through cyclic spooling motions which consist of high-tension spool-out and low-tension spool-in. Specifically, we fuse continuous-time optimal control tools, including Pontryagin?s Maximum Principle, with an iteration domain costate correction, to develop an optimal spooling controller for energy extraction. In this work, we focus our simulation results specifically on an ocean kite system where the goal is to optimize the spooling profile while remaining at a consistent operating depth and corresponding average tether length. Reed IFAC - Kite Control in Turbulence.pdf This paper presents a hierarchical control framework for a kite-based MHK system that executes power-augmenting cross-current flight, along with simulation results based on a high-fidelity turbulent flow model that is representative of flow conditions in the Gulf Stream. The hierarchical controller is used to robustly regulate both the kite?s flight path and the intra-cycle spooling behavior, which is ultimately used to realize net positive energy production at a base station motor/generator system. Two configurations are examined in this paper: one in which the kite is suspended from a surface-mounted platform, and another in which the kite is deployed from the seabed.

This dataset contains the full set of training materials used in a marine hydrokinetic (MHK) modeling workshop conducted by Sandia National Laboratories for the University of Alaska Fairbanks, funded through the U.S. Department of Energy's TEAMER program. The workshop focused on the use of the SNL-Delft3D-CEC and SNL-SWAN modeling tools, which simulate the hydrodynamic and environmental impacts of current and wave energy converters, respectively. The materials were developed to support the evaluation of physical and environmental interactions of MHK devices using open-source modeling frameworks. The dataset includes presentations, tutorials, theoretical documentation, and software setup instructions related to modeling wave and current energy devices. It covers both conceptual and real-world applications, such as channel flow and riverine or coastal sites like the Tanana River and Yakutat, Alaska. Instructions for installing and customizing the Delft3D and SWAN modeling suites with the SNL-developed modules are included, along with test cases and example scenarios. All data units and modeling parameters are labeled, and the dataset assumes access to proprietary software components (e.g., Deltares license files for Delft3D FM Suite) and some familiarity with hydrodynamic modeling tools.

Input data and heave results (unsteady RANS-VOF overset simulations performed in Star-CCM+) for a float with an ellipsoid geometry. Five extreme sea states were considered, as detailed in the conference paper "Application of the Most Likely Extreme Response Method for Wave Energy Converters" by Quon et al. (see resource below). These sea states were extrapolated from conditions near Humboldt Bay, California. Focused waves were generated using the MLER module of the Wave Design Response Toolbox (WDRT) and specified at the inlet boundary conditions. The device was constrained to heave only and a PTO was not modeled.

The core objectives of this project is to improve the power capture of three different wave energy conversion (WEC) devices by more than 50% using an advanced control system and validate the attained improvements using wave tank and full scale testing. In parallel, we will bring along the development of a wave prediction system that is required to enable effective control and test it at full scale. The purposes of this report are to: 1. Plan and document the 1/25th scale device testing at the wave-tank facility; 2. Document the test article, setup and methodology, sensor and instrumentation, mooring, electronics, wiring, and data flow and quality assurance; 3. Communicate the testing results between the associated members; 4. Facilitate reviews that will help to ensure all aspects (risk, safety, testing procedures, etc.); 5. Provide a systematic guide to setting up, executing and decommissioning the experiment.