DNV has been involved in the certification of wind turbines for more than two decades now. The high level of growth and technical achievements in the wind industry during this period has been impressive. More than 60 000 MW of wind power has now been installed world wide. This corresponds to the electricity demand for 25 million households. A total of 800 MW wind power has now been installed offshore to take advantage of the optimum wind conditions and minimal social impact.

In order to support the wind turbine industry with cost optimal design, two new technical standards have been issued by DNV. These standards cover the blades and offshore support structures for wind turbines. The rational certification requirements detailed in these standards, as well as those detailed in other industry standards from ISO and IEC are ‘corner stones’ in DNV’s type and project certification services.

Standardization in the wind turbine industry
In the early years of wind energy, local national standards for the design of wind turbines were issued in: Denmark, Germany and the Netherlands. As a result of the globalization of the wind turbine industry during the last decade, both the IEC and ISO have succeeded in developing specific standards for wind turbines and their associated components, with the development committees enjoying world wide participation by research institutions, wind turbine manufacturers and international certifying bodies such as DNV. Due to the complex organization during development, these standards are still limited to principles of safety, loads and design and type testing of selected components. DNV issue their own standards to define certification requirements were the IEC and ISO standards are still incomplete.

DNV wind turbine standards are developed with the input and review from key industry stakeholders, as well as supervision by an international technical committee.

Offshore support structures
DNV-OS-J101 “Design of Offshore Wind Turbines Structures” was issued in 2004 as the first complete standard for details of structural design of the tower and support structure for offshore wind turbines. The standard is based on DNV´s experience developed with certification of the world’s first few offshore wind farms, and includes the technical requirements directly transferred from other DNV standards for other comparable offshore structures.

The DNV-OS-J101 standard is currently being revised to serve as an interpretation on the new IEC 61400-3 standard “Design Requirement for Offshore Wind Turbines” which is a development of many of the requirements in the first edition of DNV-OS-J101.

The DNV-OS-J101 standard can be purchased and instantly downloaded at DNV's Webshop. If you have any questions, please contact us.

Blades
The latest standard released is DNV-OS-J102 “Design and manufacture of wind turbine blades”. The blades are one of the more critical and complicated components of the wind turbine.

Today IEC standards for wind turbine blades only cover load assessment, principles of structural safety and details of full scale blade testing. DNV-OS-J102 is the first standard in the industry that based on the basic IEC requirements collects all relevant certification requirements to material qualification, design calculation procedures, manufacturing procedure justification and testing of wind turbine blades. The standard meets the increased focus on blade reliability and safety from all stakeholders.

It is believed that the complexity of materials and blade designs will grow with increasing turbine sizes and structural optimisation. As a result DNV-OS-J101 provides detailed guidance throughout the blade development program, consolidating the vast amount of international experience present in the industry, and providing a basis for the blade designs of the future.

The DNV-OS-J102 standard can be purchased and instantly downloaded at DNV's Webshop. If you have any questions, please contact us.

Design of wind turbines
The "Guidelines for Design of Wind Turbines" is developed in cooperation with Risø. The first edition was issued in spring 2001 and presented at the EWEC conference in Copenhagen 2001. The second edition was issued in spring 2003.

Wind turbine power plants
The DNV Guideline for Certification of Wind Turbine Power Plants, 1992 is used in connection with our type certification work in addition to the national and international codes and standards. Please contact us for more information.