Ricardo has been assisting wind farm developers and turbine manufacturers to improve the reliability of their drivetrains for a number of years, as Paul Jordan, the company’s global head of clean energy and power generation explains: “Reliability is one of the most crucial determinants of the commercial case for wind farm developments. The ability to convert that potential into revenue for energy sold into the power grid is crucial. With our extended suite of wind energy products, Ricardo now offers a comprehensive range of innovations that will help improve reliability and avoid unplanned downtime through failures – and in doing so, reduce the total cost of energy generated.”
The suite of technologies to be presented by Ricardo at WindEnergy Hamburg 2014 includes the MultiLife bearing management system and two new products: TorqLife, which prevents overload and non-torque loads, and advanced condition monitoring enabler, SensorLife. Delegates to the show can see for themselves these exciting technological innovations and other Ricardo approaches to the optimization of the costs of wind energy generation – especially in the offshore environment – by visiting the Ricardo booth, H218 in Hall B6.
MultiLife extends bearing life by up to 500%.
Forensic investigation undertaken by Ricardo on behalf of wind energy clients has identified several bearing failure mechanisms commonly found on turbine drivetrains. For example, some are due to unequal load distribution applied to the planet bearings in epicyclic gears, while others arise due to a range of conditions including running at partial turbine power when the rolling elements are prone to skid rather than roll. This causes scuffing of the precision ground surfaces. Irrespective of the cause, wear on the inner bearing race is concentrated over a small arc of some 40° and can lead to premature failure, while the remainder of the race remains unworn.
The MultiLife concept offers the potential to address these mechanisms, thus extending bearing life by five fold. It ensures that the fatigue damage or wear never reaches a critical condition during the turbine life – an approach also applicable to the outer races of direct drive turbines subject to sustained gravity loads. Following extremely promising rig test results of the Ricardo MultiLife wind turbine bearing management system concept in a collaborative project with the University of Sheffield, it was announced in late 2013 that the system would be an area of focus for the UK government’s Department of Energy and Climate Change funded OWDIn (Offshore Wind Drivetrain Innovation) project. As part of this new initiative, MultiLife systems are being deployed at a Scottish Power Renewables wind farm location that is known to experience aggressive wind conditions.
TorqLife: Preventing overload and non-torque loads
The OWDIn project is also acting as a demonstration of a new Ricardo TorqLife system, to be revealed publically for the first time at WindEnergy Hamburg. Conventional and hybrid wind-turbine drivetrains are susceptible to non-torque loads transmitted into the gearbox. The same potential failure inducing mechanism can also affect the generator for direct-drive architectures where maintaining the small air gap is critical. Moreover, geared systems are also potentially at risk from torque overload under certain operating conditions such as gusts or turbulent wind conditions and fault conditions such as grid loss and emergency stop, where high loads can be experienced in the drivetrain before action can be taken to protect the drivetrain by controlling blade pitch.
TorqLife is an innovative dual-function coupling that avoids drivetrain overloads. It is based on an arrangement of hydraulic cylinders between the rotor shaft and gearbox, or direct-drive generator, which kinematically isolates non-torque loads and truncates a peak torque to bring it within acceptable limits. This Ricardo innovation offers the prospect of enabling wind turbine drivetrains to survive in the harshest conditions for their full 25-year operating life without major maintenance intervention.
SensorLife: Advanced condition monitoring
While intensive simulation-led design and the adoption of innovations such as MultiLife and TorqLife are aimed at delivering through-life turbine reliability, durability and drivetrain optimization, the ability to identify incipient failures in the field remains a significant commercial priority for wind farm operators.
Also revealed publically for the first time at WindEnergy Hamburg, the Ricardo SensorLife system aims to provide a practical application of acoustic emission and ultrasonic sensors with advanced signal processing techniques for detection of early-stage faults for bearing and mechanical driveline condition monitoring. With these techniques, the sensor data gives advanced warnings of system health issues, beyond current state-of-the-art, and can be used to develop remaining useful life predictions for key components in the drivetrain, whether direct-drive or geared.
“We are seeing a significant demand for Ricardo services from both wind farm developers as well as the manufacturers of the latest large-scale multi-megawatt turbines,” continues Paul Jordan. “With the imperative to push further in ensuring that the major components of the drivetrain system are sufficiently reliable as to be fit for life, we believe that our the reliability innovations we are highlighting at WindEnergy Hamburg – MultiLife, TorqLife and SensorLife – have game-changing potential to reduce the total cost of wind energy both on land and offshore.”
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