Mitigating Peak-to-Average Power Variability in Wave Energy Converter Systems: A Design Comparison

Ocean wave energy converters (WEC) with rotary drivetrains may use onboard energy storage to reduce the undesirable, large peak-to-average power ratio (PAPR) for grid-connected operation. The current energy storage system used in the Triton-C WEC developed by Oscilla Power, Inc. utilizes a bank of supercapacitors (SC) connected directly to the DC bus between the onboard AC/DC and DC/AC inverters. Contrary to this configuration, the majority of literature uses a DC/DC converter to connect the SC to the DC bus. This paper compares the two designs to determine which configuration is optimal in terms of PAPR mitigation and cost. Comparison is performed through simulations using field-based data and models. The work finds that while a DC/DC converter allows a higher utilization of the SC energy capacity, the cost of a multi- MW rated DC/DC converter outweighs the cost savings of the reduced energy storage size.