- Category: Articles
![Figure 1. White etching crack detected on a washer tested using mineral A Kluber fig 1](/images/stories/Features/2018Features/October18Images/Kluber-fig-1.jpg)
Premature failures in rolling bearings do not occur very often. In a wide range of applications including wind turbine gearboxes, however, premature bearing failures due to subsurface cracks have become increasingly reported, leading to high costs due to unscheduled downtime and unplanned maintenance efforts. The phenomenon of subsurface cracks in the microstructure of the bearing steel is often referred to as white etching cracks. ‘White etching’ refers to the white appearance of the altered microstructure when a microsection is polished and etched.
By Balasubramaniam Vengudusamy and Fabio Zanella, Klüber Lubrication München, Germany
- Category: Articles
![Figure 1. ZephIR Lidar Production Centre ZXlidar fig 1](/images/stories/Features/2018Features/Sept18images/ZXlidar-fig-1.jpg)
The progress of lidars within the wind industry has been charted from the start by Windtech International. Articles as far back as the very first edition of the publication in 2004 have highlighted not only the fundamental principles of lidar, but also its applications – onshore, offshore and turbine mounted. On 18 June 2018, a significant milestone was reached whereby vertical profiling lidars – Leosphere’s Windcube and ZephIR’s 300 model – achieved levels of IEC Classification that allow consultants, developers and turbine manufacturers to have further confidence in the technology’s ability to measure across a range of environmental conditions. The lidars were demonstrated to operate with known and low uncertainties, making them suitable for the variety of applications that have become synonymous with these remote sensing devices: from resource assessment and site calibration to formal power curve testing.
By Ian Locker, John Medley, Michael Harris and Alex Woodward, ZephIR, UK
- Category: Articles
![Figure 1. Crack in the blade at the location of a previous repair, which was detected by ping.monitor Ping Figure1](/images/stories/Features/2018Features/Sept18images/Ping-Figure1.jpg)
Up to 23 per cent of wind turbine failurescan be caused by blade damage, with up to 25–30% of wind farm operation costs spent on operation and maintenance. Current damage detection options are limited and are used on an ad hoc basis at each turbine. New innovations on the market are now allowing wind farm operators to keep a closer eye on turbines while also reducing time and resources spent on monitoring. One such solution is ping.monitor, which is an innovative acoustic solution and a world-first application of aero-acoustic analysis for wind turbine maintenance and repair. It represents a seismic shift to an efficient, responsive monitoring system that significantly outpaces previous models.
By Matthew Stead and Jon Cooper, ping services, Australia
- Category: Articles
![Figure 1. Thermographic technology now available for the wind blade inspection market Figure 1 Hensoldt](/images/stories/Features/2018Features/Sept18images/Figure_1-Hensoldt.jpg)
Thermal cameras with very high focal length were previously exclusively developed for space and defence applications. Now they are available for the civil market and bring to the wind energy sector higher quality and performance, lower Health, Safety and Environment risks and similar competitive prices to existing solutions. Based on the research work of institutes like the Sandia National Laboratories, the Federal Institute for Materials Research and Testing (BAM), Fraunhofer and private companies, the optical and thermographic inspection of wind blades becomes state of the art, so that certification bodies accept the ground-based thermographic inspection method as equivalent to the standard rope access method.
By Fabianna Tenorio and Jürgen Austen, Hensoldt, Germany
- Category: Articles
A Techno-Economic Analysis of the Concept
![Figure 1. OHRES design and layout of components KIT figure 1](/images/stories/Features/2018Features/Sept18images/KIT-figure-1.jpg)
By Mohamed Mamdouh Elkadragy, Karlsruhe Institute of Technology, Germany
- Category: Articles
![Figure 1. Model of a hybrid mini-grid used at a project presentation in a village in Myanmar (courtesy Reiner Lemoine Institut, Catherina Cader) HMG Model](/images/stories/Features/2018Features/JulAugimages18/HMG_Model.jpg)
Hybrid mini-grids (HMGs) are an ideal solution for remote settlements without energy access. HMGs are typically sized and optimised with commercial software that comes with the usual limitations and is lacking in transparency. The Reiner Lemoine Institute has attempted to develop an open-source alternative to standard software for modelling and sizing HMGs.
By Sarah Berendes, Reiner Lemoine Institut, Germany
- Category: Articles
Innovative Floating Platform for Deploying XXL Turbines
The main focus on releasing the potential of deep-water wind is how to reduce costs to make it competitive with nearshore wind. Nearshore bottom-mounted wind is now generating at nearly half the cost of nuclear.
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One way to drive down costs is to go for bigger turbines where so-called XXL units with capacities of up to 20MW are being considered. But such large units demand very stable platforms to resist the large capsizing moments. Increased stability with a floating platform means increased size and this has implications for where they can be built, what facilities can be utilised for their build, and how they can be deployed to site. This article reviews the fundamental stability consideration and how it impacts the size of the established floating platform solution of ‘spar’ and ‘semi-submersible’. The author proposes an alternative solution combining the features and advantages of the ‘spar’ and ‘semi-submersible’ – termed a ‘multifloat-spar’ – and puts forward its advantages in helping to drive down the cost of deep-water wind.
By Graeme Mackie, Oceanflow Energy, UK
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