Development and Validation of Passive Yaw in the Open-Source WEC-Sim Code: Preprint

David Ogden, Jennifer van Rij, Yi-Hsiang Yu, Nathan Tom, Dominic Forbush, Kelley Ruehl

Research output: Contribution to conferencePaper

Abstract

A passive yaw implementation is developed, validated, and explored for the Wave Energy Converter Simulator (WEC-Sim), an open-source wave energy converter modeling tool that works within MATLAB/Simulink. The Reference Model 5 (RM5) is selected for this investigation, and a WEC-Sim model of the device is modified to allow yaw motion. A boundary element method (BEM) code was used to calculate the excitation force coefficients for a range of wave headings. An algorithm was implemented in WEC-Sim to determine the equivalent wave heading from a body’s instantaneous yaw angle and interpolate the appropriate excitation coefficients to ensure the correct time-domain excitation force. This approach is able to determine excitation force for a body undergoing large yaw displacement. For the mathematically simple case of regular wave excitation, the dynamic equation was integrated numerically and found to closely approximate the results from this implementation in WEC-Sim. A case study is presented for the same device in irregular waves. In this case, computation time is increased by 32x when this interpolation is performed at every time step. To reduce this expense, a threshold yaw displacement can be set to reduce the number of interpolations performed. A threshold of 0.01 was found to increase computation time by only 22x without significantly affecting time domain results. Similar amplitude spectra for yaw force and displacements are observed for all threshold values less than or equal to 1, for which computation time is only increased by 2.2x.
Original languageAmerican English
Number of pages12
StatePublished - 2020
EventASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering -
Duration: 3 Aug 20207 Aug 2020

Conference

ConferenceASME 2020 39th International Conference on Ocean, Offshore and Arctic Engineering
Period3/08/207/08/20

Bibliographical note

See NREL/CP-5700-79137 for paper as published in proceedings

NREL Publication Number

  • NREL/CP-5000-76304

Keywords

  • wave energy converter modeling tool
  • WEC-Sim

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