What is a Wind Turbine Generator (WTG) lifetime assessment?
Historically, wind turbines were intended to have an operational life expectancy of 20 years. Over time, it’s often transpired that the actual conditions that turbines have experienced are different to those initially assumed and calculated in the original design. For instance, real wind conditions on site may be less severe than those assumed during design. Alternatively, expansions in neighbouring wind farms may have significantly increased turbulence.
Although on paper, time is up for many wind turbines, TÜV SÜD’s experience in the lifetime assessment shows that most still have service life reserves even after reaching the end of their design life. Despite two decades of wear and tear, the turbines’ supporting structures are often free from significant damage and so only need relatively minor, inexpensive repairs to allow lifetime extension.
A wind turbine lifetime extension assessment is a practical and analytical evaluation that assesses physical condition to ensure that ongoing operation of wind turbines is safe and efficient.
Wind turbine lifetime extension assessments are usually conducted in the final year of the original life span. The process involves two stages:
- Analytical assessment: determination of the potential duration of continued operation for all relevant parts of the turbine. By using software-based simulation the actual stresses and loads faced by a turbine are compared with the stresses and loads for which the turbine was designed. The results of the physical inspection are included in these calculations.
- Physical assessment: The purpose of the physical assessment is to document any damage to the equipment and any changes in the surrounding environment. Prior to the inspection, weather and performance data, as well as technical documents, maintenance and repair reports, are evaluated. Thus, the turbine can be checked for specific weaknesses and defects. In particular, the conditions of the main elements of the turbine – the rotor blade, the gearbox, the supporting structure and the foundation – are assessed. All load-bearing and safety- relevant parts are inspected for signs of corrosion, visible cracks and unusual noises in the gearbox or other gear and bearing assemblies. In addition, an investigation is carried out for weaknesses or flaws associated with particular types of turbine.
Why is Wind Turbine Generator (WTG) lifetime assessment important?
Experience shows that estimates for wind turbine life cycles can often be extended by several years beyond the original plan. Wind conditions at the site may involve lower loads than those factored into the original design and the turbine’s supporting structure is often free from significant damage. As a result, relatively minor and low-cost repairs are often sufficient enough to allow for a lifetime extension.
Conducting a lifetime assessment helps you map the lifetime extension of wind turbines for your sites, providing multiple benefits. These include:
- Improve Return on Investment (ROI)
By extending the lifetime of the wind turbines on your site, you generate revenue for longer. The results of an assessment help you confidently predict how many more years each unit can be expected to function, meaning you can design appropriate maintenance plans and forecast potential costs.
- Lower risk
The assessment on the structural integrity and safety related equipment helps to prevent from hazardous situation and major damages or total loss of the turbine.
- Predictable costs and shutdowns
The result of a lifetime assessment helps to better forecast repair and maintenance costs likely to be incurred during the remaining life of the turbine and to plan maintenance shutdowns accordingly.
- Meet insurance and compliance requirements
Completing an inspection report provides evidence to insurers and approval authorities that the machinery is still fit for purpose.
- Assessments pre-sale
If you plan to sell a wind-turbine site within its planned lifetime, it’s invaluable to complete a lifetime assessment, proving that units have been maintained and managed according to the latest standards.
TÜV SÜD assesses the suitability of your WIND TURBINES FOR FUTURE USE
TÜV SÜD has over 30 years’ experience in all aspects of wind turbine life cycle assessment. Our highly experienced teams work closely with you to understand your projects and develop an assessment plan that meets the needs of your wind farm. We provide a range of comprehensive services to support you, including:
- Site-specific wind condition analysis: data collection to evaluate the discrepancy between the actual loads that turbines have borne against those set out in the design estimates.
- Wind turbine load analysis: assessment of the loads put on the load bearing components such as blades, bolted connections, tower, gearbox, etc.
- Strength analysis of all wind turbine components: our experts conduct a range of simulations on the load bearing components.
- Technical knowledge of all major wind turbine types and manufacturers: we work with all major brands in the industry and have knowledge of turbine types dating back decades.
- Inspection know-how: our specialist teams test several thousand wind turbines per year.
TÜV SÜD is an accredited body for German Type Approval and is a globally recognised certification body with testing labs across the world. TÜV SÜD is renowned for our quality, impartiality and focus on safety and we are a trusted partner to many wind companies in the industry.
What does a Wind Turbine Generator (WTG) lifetime assessment involve?
TÜV SÜD is a world leader in wind turbine lifetime assessment and provides comprehensive analysis to create reliable predictions of wind turbine life expectancy.
Our services include:
- Initial data assessment: analysis of machine documentation, service history and meteorological data to understand whether the turbine’s components have borne the loads expected in the original design. This stage also helps provide an indication of the potential for the wind turbine’s continued operation past its originally planned lifetime.
- On-site inspection: our experts examine maintenance logs, looks for corrosion, visible cracks and unusual noises from the gearbox and bearing assemblies, paying close attention to known issues associated with the specific model of turbine. They will also assess the turbine’s immediate vicinity – changes such as expansion of the wind farm will affect local wind conditions and need to be taken into account when calculating the turbulence.
- Lifetime simulation and report: the collected information is entered into software-based models that generate a report providing accurate data relating to the expected continued lifetime of the wind turbine. You’re provided with independent analysis to inform your decision between wind turbine decommissioning versus maintenance. During this stage, recommendations for further maintenance and lifetime extension are also provided.