Shifting gears: a look at wind turbines

As countries around the world strive to reduce greenhouse gas emissions and move towards a sustainable future, wind energy has become a key element of their renewable energy strategies. In the UK in particular, the amount of energy produced by wind has increased significantly in recent years. In fact, in early 2023, wind became the country’s leading energy source for the first time in history, producing more electricity than gas and imports.

The development of wind energy in the UK and around the world is influenced by a number of technologies, one of which is wind turbine gearing.

All about gears

Modern wind turbines are complex pieces of equipment consisting of many moving parts. Some gearing is necessary to ensure their efficient operation.

A gearbox is typically used in wind turbines to convert the low-speed, high-torque rotation of the wind turbine into the higher speed required by the generator. In wind energy conversion systems, the gearbox is one of the most important elements of the drive system. Generally speaking, wind turbine gearboxes have challenging operating conditions and high expectations – these gearboxes are subject to heavy loads and are often located in locations where replacing or repairing a failed gearbox is extremely expensive.

Traditionally, these power conversion systems use mechanical transmissions to connect a high-speed electrical machine to a low-speed physical power source. However, over time, gearbox failures cause a lot of downtime, maintenance, and loss of power generation. In fact, reports indicate that for every 145 wind turbines operated annually, one gearbox failure occurs, leading to significant downtime and high costs for owners. These problems led to the emergence of magnetic gears as an alternative to mechanical gears.

Like mechanical gears, magnetic gears convert rotational power between different speeds and torques, but instead of physically engaging teeth, they use magnetic fields. By using magnets to transfer torque between the input and output shafts of the transmission, they avoid mechanical contact. This provides several benefits such as high torque density, reduced noise and vibration, less maintenance and greater reliability, inherent overload protection and contactless power transmission.

Moreover, if too much torque is applied to mechanical gears, they can be damaged. If the same thing happens to magnetic gears, they simply slide past each other without causing any damage to themselves or other parts of the system.

Innovative and efficient technology

To ensure efficiency, reliable motors – particularly innovative magnetic gear motors – are a key enabling technology for the renewable energy sector. Magnomatics offers revolutionary magnetic gears that have been used in a number of innovative industry solutions, including: in offshore wind energy.

Designed to overcome the torque limitations of conventional direct drive electric machines, the company’s patented Pseudo Direct Drive (PDD) consists of a magnetic gear mounted inside the stator. The outer magnetic components of the magnetic gear are attached to the inner bore of the stator, and the copper windings in the stator are used to drive the inner rotor of the magnetic gear.

It is a relatively fast electric motor with a relatively low load, which results in low currents and, therefore, low temperatures. This, in turn, ensures high efficiency, long service life and prevents demagnetization of the external magnet system. The torque in the inner rotor is then increased in a novel pole piece rotor, typically in the range of 5 to 10:1.

Simulations showed that the PDD is less than two-thirds the size of an equivalent permanent magnet motor and half the length of an induction motor. Moreover, it can be designed to be 2-3% more efficient without sacrificing torque density.

The result is a very compact and highly efficient engine; ideal for wind turbines as they have excellent performance even at part load due to wind unevenness, which is where most operations take place. In fact, the PDD’s performance is excellent under these conditions as it still operates almost at nominal values.

The technology is becoming more and more recognized around the world, not only for offshore wind, but in many applications, including marine propulsion, automotive and wider industry.

Did you like what you’ve read so far? Read the full article and the rest of the spring issue Global Energy by clicking the link or below, or register for free today!

More news and technical articles from the global renewable energy industry can be found in the latest issue of Energy Global magazine.

Energy Global Spring 2024 issue

The Spring 2024 issue of Energy Global begins with guest commentary from Field on how battery storage can serve as a viable solution to reduced energy consumption, before moving on to a regional report by Théodore Reed-Martin, editorial assistant at Energy Global, looking at the state of renewable energy sources in Europe. This issue also includes a number of technical articles on electrical infrastructure, turbine and blade monitoring, battery storage technology, coatings and more.

Read the article online at: https://www.energyglobal.com/special-reports/29052024/changing-gears-a-look-at-wind-turbines/