Abstract
Marine renewable energy (MRE), derived from ocean waves and tidal currents, presents a carbon-free, sustainable power source which is particularly beneficial in remote areas with limited access to electricity. Several applications, such as power for ocean observing buoys or small autonomous surface vehicle (ASV) recharging, offer an immediate opportunity for MRE to demonstrate feasibility. These applications often have small-scale (<1KW) power requirements and necessitate high system efficiency to be competitive with alternate renewable sources of power and to overcome the cost of installation. However, tidal energy is often characterized by high peak power output and low mean power. To succeed in wider ranges of voltages and power in tidal energy generation, robust power electronics and precise control must be able to maintain efficiency while handling high peak to mean power output. Currently, tidal energy lacks a commercial-off-the-shelf (COTS) option for handling such wide range of power conversion efficiently.
We are currently in the process of developing, and will have developed by the time the conference rolls around, a high-efficiency power converter with a maximum power point tracking (MPPT) controller specifically designed for a wider range of tidal energy output. This converter will be a combination of an active rectifier with a full bridge DC to DC converter. It is designed to function efficiently across wide range of input voltages and frequencies for AC to DC conversion, leveraging new Gallium Nitride (GAN) FET technology. This power converter will enable increased switching frequency, decreased power losses, and smaller component size. Furthermore, the introduction of a controlled active rectifier will enable bidirectional power harvesting, enhance AC to DC conversion efficiency, and allow for bidirectional power transfer to supply power to the turbine when necessary. Additionally, adaptive duty cycle hill climbing control will be implemented to achieve the maximum power point. This warrants further investigation and will be incorporated as the design matures. To validate the novel design, we will use a MATLAB-Simulink model previously designed by PNNL (Figure 1). The simulation models tidal turbine and generator dynamics under controlled tidal velocities with custom power electronics and control methodologies. The model will be used to characterize the efficiency of the custom power electronics and MPPT algorithm under varying tidal inputs, and to refine the design. Successful validation of the design in Simulink will be followed by benchtop testing with PNNL’s hardware-in-the-loop tidal turbine emulator, which produces 3-phase power as modeled by the Simulink Simulation. The integration of advanced MPPT control algorithms, bidirectional power harvesting capabilities, and integration GAN FET will enhance the performance and efficiency of tidal energy conversion systems for wider voltage ranges, leading to greater energy output and improved viability of tidal energy as a renewable source. Furthermore, the development of the MPPT design and its validation through benchtop testing will aid researchers in conducting precise testing, analysis, and design refinement within simulation environment.