From 4,000-year-old windmills in Persia to floating wind turbines in the North Sea, wind energy has evolved from rudimentary to highly advanced. Patricia Vázquez, Carbon Key Account Manager at Exel Composites, explores how qualification processes influence the implementation of new designs and the standards that guide their manufacture.
Exel Composites
The different design specifications, components, materials and environmental conditions can complicate production. OEMs may specify blades with various lengths, profiles or raw material weight fractions, ranging from thin, narrow profiles with several kilometres of material to thicker, larger plates for added rigidity. For example, offshore blades are often more than 100 metres and must withstand immense loads. This rigidity helps prevent excessive bending during operation, which may result in the blade striking the turbine tower.
All designs must meet consistent performance standards, including aerodynamic efficiency, strength and fatigue resistance, provided in general Standards like IEC 61400-5:2020 and DNV-ST-0376. Each design requires customised materials, production processes and extensive testing, leading to higher costs and longer production timelines.
APQP4Wind was established to standardise quality assurance practices across the wind energy sector. This non-profit organisation employs principles from Advanced Product Quality Planning (APQP) to streamline product development and approval processes. It aims to propagate consistency, reduce the cost of non-quality and accelerate the time spent on the market by standardising documentation, testing and quality assurance.
- Testing and qualification
Qualification and testing are crucial to ensure wind turbine blades meet industry standards. Certified testing facilities in Germany and China are integral to this process, as they perform extensive evaluations of turbine component materials and designs. For instance, Exel supplies testing of the carbon spar cap, which involves mechanical and fatigue examinations conducted by these external laboratories to validate compliance with the OEMs’ specifications.
These assessments validate that materials can withstand operational stresses and environmental conditions. Materials are then tested for their durability and performance under simulated operational conditions. These include exposure to freezing, thawing and high humidity to evaluate their resistance to environmental degradation.
The pre-production approval process (PPAP) typically lasts three to six months and involves quality and paperwork checks on three to thirty blades. Delays can occur if customers need to adapt their manufacturing processes for new materials. Certification from bodies like DNV requires additional blade testing, increasing time and costs. This means that transitioning from initial requirements to serial production can take up to three years.
Navigating these challenges demands experience and innovation from the blade component manufacturers. Exel Composites works closely with turbine OEMs to ensure compliance with standards. This includes customised manufacturing processes and qualification tests, ensuring each blade meets performance and safety criteria.