Standards Development

Scope

The scope of this standard is the assessment and reporting of site specific offshore-only (or near- shore) wind resource and energy yield uncertainty for wind power stations (WPS). This includes the following key scope components:

• Incorporation of all applicable elements from 61400-15-2

• all measurement, analysis and evaluation steps unique to offshore WPS including data analysis, modeling, loss assessment and net energy production estimation such as required to make the results reproducible and traceable to national standards

• definition of documentation and reporting requirements to make the results traceable to national standards

• definition of a digital exchange format for offshore wind energy yield reporting to facilitate efficient information exchange

• a standardized normative approach to the uncertainty quantification of a site-specific offshore wind energy yield assessment

The standard will include in its scope the assessment of site-specific wind conditions and related parameters to determine the potential energy at a prospective offshore wind power station.

Specifically, the suitability of methods already in use by the wind industry for the stated purpose should be discussed and agreed. These methods include but are not limited to data processing, single lidar measurement and modeling assessment and uncertainty methods, sway losses for floating offshore WPS and other losses that require refinement in the offshore context, long term correction such as MCP (Measure Correlate Predict), power curve modeling, long-range WPS-to-WPS and internal turbine interaction modeling, site optimization and use of reanalysis data or any other currently applied methods known to the experts of the project team. Areas where scientific consensus in lacking will be included as informative annexes.

Scope limitations:

According to IEC 61400-1, IEC 61400-3-1 and IEC 61400-3-2 the site specific offshore conditions can be broken down into wind conditions, other environmental conditions, soil conditions (in this case sea floor), and electrical conditions. Wind conditions can be subdivided into normal and extreme conditions. All of these site conditions other than site specific wind conditions and related documents are out of scope for this standard.

Existing Work:

The proposed work is an extension and completion of IEC 61400-15-2 which has been recently submitted as a Committee Draft (CD) and which did not include all of the aspects related to offshore wind energy yield assessment reporting and uncertainty characterization.

Purpose

Market relevance: Offshore wind energy yield assessment (EYA) is one of the key steps in establishing an offshore wind power station that is currently not standardized or in some aspects not covered by the 61400-15-2 standard (now in CD). This standard would augment 61400-15-2 to address unique aspects of offshore wind energy yield assessment, uncertainty and reporting. The large variation in approaches used by different actors in the wind industry particularly as regards turbine interaction (wakes/blockage/farm-to-farm effects), the sparsity and type of offshore measurement equipment, as well as the lack of traceability observed in certain situations leads to potentially high uncertainty on the expected energy yield for a given offshore site and a high risk to potential developers and investors. If not adequately characterized, this high risk can directly impact the competitiveness of wind energy projects in the market. A common approach to the uncertainty methodology and reporting requirements will provide a common basis for offshore wind EYA for developers, OEMs, independent engineers, certification bodies, end users, and financial institutions.