Start Date

5-2020 12:00 AM

Description

This paper presents a comparison of three methods for expanding the wake for use with wake expansion continuation (WEC) optimization. A process related to continuation optimization methods for reducing multi-modality in the wind farm layout optimization problem. A reduction in multi-modality is achieved by starting with an increased wake spread, while maintaining normal velocity deficits at the center of the wakes, and then reducing the wake spread for each of a series of optimization runs until the standard wake spread is used. Three wake expansion methods were tested: (1) increasing the wake expansion angle, (2) multiplying the wake diameter, and (3) multiplying the wake diameter in the far wake and allowing the near wake wake spread angle to increase so that the near wake and far wake are the same diameter at the point of far wake onset. Tests were run with a range of optimization steps and maximum spread amounts to determine which spreading approach is best and what the best parameters are to use with the spreading methods. A 38-turbine wind farm was used as the test case. Optimizations were run from 200 different starting positions with a gradient-based method (SNOPT), and using WEC along with SNOPT. The diameter spreading approach was found to be the most effective. These results are likely specific to the test cases and may not be generally representative.

Comments

Due to COVID-19, the Symposium was not able to be held this year. However, papers and posters were still submitted.

Available for download on Saturday, May 01, 2021

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May 1st, 12:00 AM

Comparison of Wake Expansion Methods for use in Wake Expansion Continuation Optimization

This paper presents a comparison of three methods for expanding the wake for use with wake expansion continuation (WEC) optimization. A process related to continuation optimization methods for reducing multi-modality in the wind farm layout optimization problem. A reduction in multi-modality is achieved by starting with an increased wake spread, while maintaining normal velocity deficits at the center of the wakes, and then reducing the wake spread for each of a series of optimization runs until the standard wake spread is used. Three wake expansion methods were tested: (1) increasing the wake expansion angle, (2) multiplying the wake diameter, and (3) multiplying the wake diameter in the far wake and allowing the near wake wake spread angle to increase so that the near wake and far wake are the same diameter at the point of far wake onset. Tests were run with a range of optimization steps and maximum spread amounts to determine which spreading approach is best and what the best parameters are to use with the spreading methods. A 38-turbine wind farm was used as the test case. Optimizations were run from 200 different starting positions with a gradient-based method (SNOPT), and using WEC along with SNOPT. The diameter spreading approach was found to be the most effective. These results are likely specific to the test cases and may not be generally representative.