Approach and Methodologies. The new OC5 extension will be named the Offshore Code Comparison, Continued, with Correlation, and unCertainty (OC6), and will be performed through technical exchange among a group of international participants coming from universities, research institutions, and industry. Past participation in the OC3, OC4, and OC5 projects has included the United States of America (U.S.), Germany, France, Italy, Denmark, the United Kingdom (UK), Spain, the Netherlands, Finland, Norway, Sweden, China, Portugal, Greece, Japan, and Korea. Most of the coupled aero-hydro-servo-elastic codes that have been developed for modeling the dynamic response of offshore wind turbines have been tested and further developed within OC3, OC4, and OC5. These projects have highlighted areas of the tools where further investigation is needed to understand their accuracy and correct use. The goal of OC6 is to perform more focused validation projects and development to address the identified issues and limitations within the previous OC projects. Draft Work Plan WP1: Validate the nonlinear hydrodynamic loading on floating offshore wind support structures Period: January 2019 – December 2019 Coordinator: NREL A floating semisubmersible wind turbine design, developed by the DeepCwind consortium, was used for the verification of numerical modeling tools within OC4, and then for validation (based on tank testing at MARIN) within OC5. The results in OC5 showed a persistent under-prediction (about 20% on average) of the motion and structural loads in the system across all load cases, including wave-only and combined wind-wave conditions. Similar levels of under-prediction have been observed by other floating wind developers for semisubmersibles. The OC5 results indicate that much of this under-prediction originates from the low-frequency response of the system at the surge/pitch natural frequencies resulting from nonlinear hydrodynamic loading. This work package will therefore focus on better understanding this low-frequency response behavior and the applicability of engineering-level hydrodynamic models for predicting the nonlinear hydrodynamic loading. In support of this work, a simplified version of the OC5-DeepCwind semisubmersible was re- tested at MARIN in October, 2017 without a wind turbine. Further testing at MARIN is planned for June, 2018. A full uncertainty assessment of the tests will be performed to characterize the uncertainty margins in the nonlinear hydrodynamic response levels obser...
Approach and Methodologies. This task contained four work packages described below and in Table 1. WP0: Management and coordination Leading Organization: Wind Energy Institute of Tokyo in Japan WP0 contains the technical and administrative management and coordination activities of the Operating Agent (OA). The WP primarily focuses on the communication of essential information between the participants on the achievement of the technical objectives according to the time schedule of Section 5. The WP also includes the activities which are required to inform the IEA Wind Executive Committee. A dedicated project web site will be developed for the coordination of the project.
Approach and Methodologies. The activities of the new IEA Task are divided into four subtasks as presented in Table 1. The table presents the scope and the topics in which each subtask will concentrate on. Next, the scope of each subtask and the planned activities are elaborated. The activities described in this section are to be fully defined as the project progresses. An updated and detailed organization of the activities is kept in the annexed documented “Description of Work packages”.
Approach and Methodologies. The activities of the new IEA Task are divided into four subtasks as presented in Table 1. The table presents the scope and the topics in which each subtask will concentrate on. In addition, optional aspects are given in at the lower part of the table, which could come into consideration after agreement with the Participants at the initial workshop and after sufficient process on the main subjects. Next, the scope of each subtask and the planned activities are elaborated. Table 1: Scope and contents of the four subtask Subtask I: Lidar measurements Comprehensive efforts have recently been undertaken to quantify the accuracy of lidar measurements and their comparability with standard anemometry. This has revealed a high complexity which reflects different sources of error, compared to standard anemometry. The sources for uncertainty have to be properly assessed in order to provide reliable measurements. Guidelines to perform such assessment are needed due to the different technologies applied, and the fast development of new methodologies and systems which makes comparability difficult to the end-user. Subtask I will request all participating institutes to re-run their calibration processes adopting other procedures already developed for lidar systems by other member organizations. This will reveal the benefits and issues of performing cross-calibrations, leading to refined procedures leading to new and commonly approved wind lidar calibration procedures. This task can benefit from the results of several projects such as the Work Package 6 of the European UpWind project, the German RAVE-LIDAR project, etc.
Approach and Methodologies. The activities for this IEA Task are divided among three topical work packages (WPs) organised by stakeholder groups, for simplicity’s sake meteorologists (WP1), forecast vendors (WP2) and end users (WP3). Academics are involved in all three topical WPs. Additionally, Management of the Task is in its own work package (WP0). The four WPs are synergistic and will be executed simultaneously. All four WPs run throughout the whole Task period (M1-M48). Since many activities and work areas span across multiple WPs, Work Streams (WSs) are defined as cross-cutting activities. The individual WPs are therefore mainly administrative units, while the topical work is going on in the work streams. Each WP has some WS it is responsible for, plus some collaboration in other streams that touch the area. Where applicable, the work to be done is detailed out in the individual WPs under the WS description.
Approach and Methodologies. In addition to a management work package (WP0), the proposed scope of this task focused on four technical areas where specific engagement in needed, namely supporting collaboration and research leading to the update of standards specific to small and mid-sized wind turbines (WP1), the need to develop and make available a way to share data about DW research and information as no central, global way currently exists (WP2), expand learning and support in the integration of DW into the expanding distributed generation markets, with a focus on the mini-grid/off-grid markets and distributed generation markets (WP3), a concerted effort to expand the collaboration of extensive research that is ongoing around the world in areas that can or could address specific challenges associated with DW but are not because of a lack of knowledge or understanding (WP4) and finally an effort to collaborate on innovative research to lower the cost of wind turbine technology (WP5). A table of the WP and some sub-tier efforts is provided in Table 1. It is proposed that each WP will be operated as independent work efforts, with an identified topical lead and defined research paths leading to specific results. WP4 will focus more on cross cutting collaboration and will act as a conduit of information between existing work areas, other research efforts known to task members and the key work efforts being undertaken within IEA Wind and other IEA efforts. In a process modelled from PV research collaborations, the task will meet semi-annually to allow face to face meetings of the different WP as appropriate, but also allow continued cross collaboration between the WP. To the extent possible these meetings will take place in collaboration with other related efforts, supporting the wider efforts at the heart of WP4. The Operating Agent (OA) will initially lead WP0 and WP4, with identified leaders or co-leaders in the other four work areas to facilitate engagement. Quarterly calls or meetings will take place between the OA and leaders of all of the WP to insure ongoing collaboration across the combined Task. Table1: Work Packages No WP Sub-WP Lead Organization Milestones WP0 Management and coordination Technical & administrative management NREL/PNNL M1-2 WP1 Progressing distributed wind technology design standards for small and mid-sized wind turbines to allow for accelerated innovation and improved consumer confidence. Wind turbine standards Assessment NREL M3 Compendium of standards recom...
