Performance Comparison of GE 1.5xle HAWT for VSVP and FSFP Control Strategies and Erosion Effect on AEP Losses

Abstract

Erosion of leading edge of wind turbine blade is a serious issue with many consequences such as degraded blade aerodynamic performance resulting in reduced power outputs, and compromised blade strength which reduces the life of wind turbine. Recently, there is a surge in the research efforts, both experimental and numerical, to study the leading edge erosion phenomenon and to quantify its affects. The presented research work uses high-fidelity computational fluid dynamics (CFD) simulations to study the aerodynamic behaviour and power output efficiency of wind turbine blade and to study the impact of leading edge erosion on the power output performance of wind turbine. The current case study is related to the GE 1.5 xle wind turbine, which is installed at various windfarms in Pakistan. Numerical results at various wind speeds are validated by comparing the

performance curves (power output, coefficient of performance, coefficient of thrust) ob- tained from CFD simulations with the manufacturer curves. The CFD results are nicely

mapped onto the manufacturer curve, thus validating our numerical scheme/ setup. The validation studies are done for the Variable Speed-Variable Pitch (VSVP) wind turbine control strategy. Validation studies are followed by a detailed comparative studies for Fixed Speed-Fixed Pitch (FSFP) and Variable Speed-Variable Pitch (VSVP) control strategies. The VSVP is found to be more efficient than the FSFP scheme because it follows the ideal power curve by using speed controller at below rated speed and pitch controller at above rated speed. Finally, numerical studies are performed to assess the impact of leading edge erosion on the power oupt of 1.5 xle wind turbine at various erosion levels. Annual Energy Production (AEP) loss is calculated for 0.5%, 1%, 1.5%, and 2% erosion of the total chord of the S818, S825, and S826 airfoil. Annual wind speed data for the site of the selected wind farm is used for AEP calculations. Results showed a 23%, 26%, 29% and 34% decrease in AEP of wind turbine for 0.5%, 1%, 1.5%, and 2% erosion respectively. Since the erosion is applied along the whole length of the blade

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and eroded blade is not modeled as per the actual erosion patterns, the AEP loss values may be exaggerated to some extent. Nevertheless, significant AEP losses suggest that maintenance of the blades at early stages of erosion is beneficial, and the associated maintenance costs are justified by the resulting power gains and increased life of the wind turbines.