4 ms·
The article deserves at least a nomination for bad technology writing, because it doesn't explain why this is such a good thing. The problem it is trying to so
by angry_octet 11y ago
The article deserves at least a nomination for bad technology writing, because it doesn't explain why this is such a good thing.
The problem it is trying to solve: wind turbines have a significantly variable range of speeds/energies. The wind speed varies significantly from the bottom to the top. It is desirable to have the generators directly produce power at 50/60Hz grid frequency to avoid needing lots of power electronics. To match this variable but low speed system to the generator you need a gearbox. (There are other systems using low freq generators but I'm vague as to how they work.)
A conventional gearbox (ie cogs) which can handle the massive energy transmission is expensive enough, but one which can change gears to deal with a range of input speeds is even more expensive and heavy. Since the gearbox is at the top of the turbine tower it also makes construction and maintenance more difficult. Many turbines spend time with their blades locked because the wind is too strong - they would turn too fast for their gearbox to handle. Also significant downtime for gearbox repairs.
The alternate solution is to change from kinetic rotational energy to hydraulic transmission, where the blades drive a pump, which pumps a fluid, which drives a motor, which is directly connected to an electric generator. These hydraulic systems have good power density and reliability but typically suffer from low efficiency if not at full load (high frictional losses from un-required piston actions).
The innovation is that they are able to achieve high efficiency in the pump/motor at a variety of input loads through use of computer controlled valve actuators. This doesn't sound that revolutionary, and indeed people have been working on it for a long time, but maybe they have something that works.
http://hydraulicspneumatics.com/hydraulic-pumps-amp-motors/hydrostatic-transmissions-power-play-wind-turbine-design http://hydraulicspneumatics.com/hydraulic-pumps-amp-motors/h...
- Mithaldu 11y agoThanks a lot. That explanation is excellent and makes a lot of sense. :)
- zeristor 11y agoGreat write up. YouTubing for this I found this great video from 6 years ago: https://www.youtube.com/watch?v=OAWI2mI73vw https://www.youtube.com/watch?v=OAWI2mI73vw It seems they invented this technology for wave power, some fancy engineering. I wonder if they can retrofit present turbines with this new tech.
- zeristor 11y agoThis a further video about the design and engineering of the hydraulics: https://www.youtube.com/watch?v=P1wZb_RKRQg https://www.youtube.com/watch?v=P1wZb_RKRQg
- Gravityloss 11y agoAFAIK no large wind turbines change gears. All have constant speed(1) and variable blade pitch. (1): gusts can change that momentarily. No mechanical gear could react to gusts anyway.
- angry_octet 11y agoYou are correct, it was a badly written explanation of why they don't change gears. All of the conventional ones use lots of power electronics to chop it up into a nice sine wave.
- Gravityloss 11y agoAnd actually I was not correct, the modern wind power plants are variable speed. This has an explanation why it's not always useful to go at max speed: https://en.wikipedia.org/wiki/Tip-speed_ratio https://en.wikipedia.org/wiki/Tip-speed_ratio In general, the modern technology trend has been replacing mechanical components with electrical ones. Frequency converters have become successful, and they have no moving parts and are very efficient. On the other hand, if this can get rid of the mechanical gear at the same time, it might be a wash. But since Vestas and Mitsubishi wind power are combining and it seems the hydraulic technology used in that Mitsubishi prototype power plant will not see immediate use. Ironically, ABB and Mitsubishi developed the integrated gate commutated thyristor that's used for those frequency converters. https://en.wikipedia.org/wiki/Integrated_gate-commutated_thyristor https://en.wikipedia.org/wiki/Integrated_gate-commutated_thy...