How Are Wind Turbines Installed?
Wind turbines are a common feature of the UK landscape. According to a recent government report in 2019, wind generators became the UK’s second largest source of electricity, providing 64 TWh. This was almost one fifth of the UK’s total generation, achieved by record onshore and offshore generation despite suboptimal conditions for wind, with 2019 seeing the lowest average wind speeds since 2012.
But what goes into the process of planning a wind turbine installation? From a huge offshore wind array, to a more modest set of turbines to help power a farm or provide electricity to a remote area, many of the steps are the same.
Perhaps the longest part of the process is that of planning. A site survey needs to be carried out to monitor local wind speeds over a period of time, usually at least three months. As a guideline, for a wind turbine to be economically viable, there needs to be an average wind speed of at least 5 m/s and in an area with minimal turbulence from surrounding trees or buildings.
Planning permission may need to be granted, depending on the geographic location and usage. If in doubt, the local planning officer should be notified before any construction is started. It is good practice to discuss plans with neighbours, to avoid any ill-will or indeed planning objections. Mortgage and insurance providers may need to be notified too.
Foundations and Trenches
Part of the planning process links directly to the subject of designing and creating suitable foundations for the wind turbine. A topological survey is needed to study the optimal place to site the turbine. A geological survey will help determine the types of supports and screw piles that may be required. Wind Turbine installations must cope with a combination of alternating vertical, over-turning moment and lateral loads. Often four conical anchors, each able to resist lateral loadings up to 5 KN are used, providing suitable support in a range of soil conditions. Specially designed plates allow adjustments to ensure the vertical pylon towers can move safely, with around 75mm of movement being accommodated in all directions.
An earthing survey assesses the ground resistivity to help design the electrical earth system. From this information, foundation work for the turbine, transformer, and substation (if required) can begin.
In addition to creating suitably stable foundations, trenches must be dug to lay the electrical cables. The exact specification will depend on the various survey results, with the resulting trenches and cabling connecting the turbine, controller, and transformer, etc. An electrical engineer will connect the DC output of the turbine, through a controller, to an inverter and then into the grid, via an Ofgem-approved generation metre.
Installing the Tower, Nacelle, and Turbine
Once the foundations have been securely laid, it’s time to start erecting the wind turbine assembly. The exact process depends on the scale of the turbine; however, the order is similar in most cases. Weather, in particular wind strength, plays an important part in selecting the exact dates to erect the turbine! The mast is erected using a crane, either as a single unit, or in multiple parts. Once secured, the nacelle containing the generator is hoisted on top of the mast, and secured in place. Finally, the turbine blades themselves are lifted and attached to the generator. For smaller turbines, the complete assembly can be built horizontally and then carefully raised into place.
Once the mechanical components have been assembled and tested, an electrical engineer can combine them with the previously laid wiring and electronic systems. Connection of the completed system to the grid happens in conjunction with your local District Network Operator (DNO). Final electrical safety and performance checks are carried out and documentation such as maintenance manuals, warranties and registration details are provided. The turbine is ready to generate green electricity. Just add wind!
How Can ABC Anchors Help?
ABC offers a wide range of screw piles including the Conical Anchor System, ideal for wind turbine installations. Our experience on projects such as the Easter Glentore Wind Farm is a great example. ABC Anchors were asked to install screw piles along the subsiding edge of both substation units and bring them back to level using underpinning jacking brackets. The project needed careful planning due to the potential damage to the underground cables during the pile installation and the cost of having the wind turbine shut down for longer than necessary. The project was a great success, and the client was delighted, saying “This was our first time using a screw piling system and I would highly recommend it, I would give the guys a 10/10!”
If we can help you with your wind turbine project, we would love to hear from you. Please get in touch.