Posters

Abstract

The installation of offshore meteorological (met) masts is both costly and time-intensive, driving the increased adoption of remote sensing devices as more economical and efficient alternatives. Among these, floating LiDAR systems have gained prominence; however, their turbulence intensity (TI) measurements are not accurately correlated with those obtained from traditional cup anemometers. This poses a critical challenge, as TI is a key determinant of wind turbine loading and a fundamental parameter for wake modeling. As such, TI measurements influence wind farm energy yield predictions, turbine selection, and capital expenditure. Dual Doppler Scanning LiDAR (DSL) systems present a promising alternative to traditional cup anemometers for measuring offshore wind resources (WRA), particularly TI. These systems operate in dual mode by synchronizing two units to target the same measurement location. This dual mode setup facilitates Wind Field Reconstruction (WFR) and the profiling of TI at the site by combining wind speed data from both Line of Sight (LOS), without assuming homogeneity in the wind field. While the IEC-61400-50-5 standard for DSL measurements is still under development, the industry views this technology as complex and in its early stages, with no established normative guidance. In 2024, following the issuance of NEDO guidelines in Japan [1], DNV published guidelines on dual scanning LiDAR measurements for WRA [2]. Although these guidelines provide valuable insights, there is still insufficient evidence to showcase the full capabilities of DSL systems, and the reliability of TI measurements remains unproven. Therefore, establishing a track record for DSL applications, particularly for offshore TI, remains essential. To evaluate the performance and capabilities of DSL to support offshore projects, four different OEMs were compared against offshore met masts at two different sites. The Blyth-Newbiggin site (UK) and the Mutsu-Ogawara site (Japan) were selected for this study, featuring met masts 7 and 2 km off the coast respectively, for respective measurement periods of 8 and 4-months. The project is structured around three distinct objectives, each addressing specific technical challenges related to DSL systems. Device installation and pointing accuracy calibration, the impact of setup parameters, and the assessment of impacts of environmental conditions. By utilizing scanning LiDARs from different OEMs, the project not only provides a comprehensive performance evaluation, but also aids determining an optimized scan configuration.  In the first phase, the systems have been continuously measuring with a consistent setup to gather evidence of their baseline measurement capabilities, serving as a basis for comparison in subsequent phases of the study. Preliminary results from this phase show promising wind speed correlations (R² > 0.99) across different systems. The second phase focuses on the impact of several critical setup parameters, such as probe length and accumulation time. The third phase aims to establish best practices for multi-point scanning modes, including vertical profiling. The outcome of our study has the potential to showcase the reliability and accuracy of DSL systems, thereby enhancing the characterization of wind conditions at offshore sites. [1] NEDO, Offshore Wind Measurement Guidebook, 2023. [2] DNV, Guidelines on dual scanning lidar measurements for wind resource assessments, 2024.