Abstract
Ocean wave energy conversion plants that use hydraulic power take-offs (PTOs) have been configured so that the working fluid must travel a significant distance (of several hundred to a few thousand meters) from the wave energy converter (WEC) located offshore to equipment onshore. With the pulsatile flow generated by the WEC having a peak period in the range of 3 to 12 seconds, the wavelengths of the excited pressure waves approach the length of the pipelines themselves. By the standards for modeling pipelines presented in popular fluid power and related textbooks, the system models for these plants should include distributed parameter models of the pipeline dynamics that capture the pressure wave delay effects. This work tests the importance of pipeline model fidelity for wave energy conversion plants. Simulations have been conducted of a simple but representative hydraulic PTO for wave energy conversion and incorporate several common lumped and distributed parameter pipeline models for comparison. These results are used to show the degree to which model fidelity effects several design metrics that are especially useful in the preliminary design phase of system development. The pipeline models used include: 1) a short line model that includes lumped resistive effects only, 2) a medium line model that also includes lumped inertial and capacitive effects for a single pipeline segment, 3) a long line model that uses repeated, lumped parameter line segments to approximate the distributed parameters of a real pipeline, 4) a simple method of characteristics solution to the one-dimensional momentum and continuity equations assuming a fixed wave speed, and 5) a discrete free-gas cavity model augmenting the simple method of characteristic pipeline model. The results suggest a relaxed standard for modeling pipelines in the case of this type of system, in which case, the recommended model is easily implemented in variable time step solvers and CAD software such as Simscape Fluids and can be used within the WEC-Sim modeling framework developed by the National Renewable Energy Lab.
| Original language | English (US) |
|---|---|
| Title of host publication | Proceedings of ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021 |
| Publisher | American Society of Mechanical Engineers (ASME) |
| ISBN (Electronic) | 9780791885239 |
| DOIs | |
| State | Published - 2021 |
| Externally published | Yes |
| Event | ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021 - Virtual, Online Duration: Oct 19 2021 → Oct 21 2021 |
Publication series
| Name | Proceedings of ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021 |
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Conference
| Conference | ASME/BATH 2021 Symposium on Fluid Power and Motion Control, FPMC 2021 |
|---|---|
| City | Virtual, Online |
| Period | 10/19/21 → 10/21/21 |
Bibliographical note
Funding Information:This research was supported in part by an appointment with Marine and Hydrokinetic Graduate Student Research Program sponsored by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, and Water Power Technologies Office. This program is administered by the Oak Ridge Institute for Science and Education (ORISE) for the DOE. ORISE is managed by ORAU under DOE contract number DESC0014664.
Publisher Copyright:
Copyright © 2021 by ASME.All right reserved.
