Savings in the wind
Energy in Germany should remain affordable.
Within the framework of the energy revolution that has been decided upon, this
demand has led to petitions, white papers and round tables of experts looking at feed in
tariffs. For manufacturers of wind turbines this has also resulted in the need to
examine their production costs critically under a microscope, right down to the last
welding joint.
No sector in the field of renewable energy has grown so strongly in recent years as wind
power – despite the pricing pressure exerted by the driving forces behind the growth, namely
China and India, and despite the tendency towards saturation in some Western markets. And
fortunately many German manufacturers are still experiencing a tailwind even with these
difficult market conditions. They obviously were able to correctly recognise some signs of the
time. In Germany efficient, powerful turbines are designed and built for export and they have
been particularly successful in reducing production costs in this high-price manufacturing
location.
Functioning or Standstill– encoders can decide. Reducing costs within the manufacturing
of a wind turbine concerns all areas. From the substructure to the rotor, no setscrew remains
unchecked. A development that does not spare the sensor technology within the turbine
either, and that includes the encoders that look after the positioning of the generators.
Although encoders only represent one percent of the costs of a turbine, and thus just a small
part of the manufacturing costs, even here every decimal place counts. And this is how it
should be, when the forward-looking system designer is calculating beyond these basic
costs: in the worst case scenario a small sensor during maintenance and repair can become
the great unknown factor in the cost calculations. Encoders, even though they are so small,
play a decisive role when it comes down to it in smooth running or standstill. When saving,
as in all concept areas, a sense of proportion is key. Yes, by all means cut costs, but never
at the expense of service life and quality.
Cost driver N°. 1: Too much of a good thing
For just these reasons Kübler developed the Sendix F58 encoder, tailor-made it seems for
wind turbine manufacturers. The F58 has been cost- optimized in accordance with the
stipulation of being “lean”.
At Kübler Lean Design refers to use and requirements, but never to a compromise on
functionality. In a process that is laid out for constant levels of quality, the F58 encoder is
firstly packaged in the robust 58 size housing; for however high the cost-sensitivity was,
there was just no way round using the interlocked Sendix bearings and the sturdy die-cast
housing- that would have been making savings in the wrong place.
Cost driver N°. 2: Extra service
With regard to the technology the Kübler Design Team opted for the fully-optical Intelligent
Scan Technology. This is especially good at addressing applications with very high bearing
loads, but also however offers a key cost advantage for wind turbine manufacturers. The
scanning occurs on a non- contact principle and is thus free from wear. If one bears in mind
that the maintenance and repair costs for a wind turbine over an operating life of 20 years
amount to approximately half of the overall costs, then it quickly becomes clear that this
benefit pays off in a very short time. Service costs are expensive, especially when the work is
undertaken at great heights. If one takes into consideration that two fitters require at least
half a day to get into the turbine, then the extent of the cost of this special maintenance soon
becomes evident.
Cost driver N°. 3: Re-inventing the wheel
Today manufacturers of wind turbines are also ‘thinking safe’. The Machinery Directive
2006/42/EU has left its mark, be it with regard to retrofitting, upgrading or re-designs. Here
Kübler offers its wide experience and a fully-developed portfolio of safe incremental and
absolute encoders. When combined with the new Safety M safety modules, total safety
solutions that monitor speed and position in line with the new guidelines can be implemented
both easily and flexibly. The optimal coordination of Safety-M modules and Sendix SILencoders
has been well-proven and thus helps simplify the certification of the overall turbine.
In place of three independent components – the operational control system, the safety
control system and the speed monitor – now all that is required is the Safety-M controller with
its encoder inputs and digital inputs; it takes care of all safety-related functions in one device.
For each functionality all that is needed in this total solution is the use of one Sendix encoder
in place of the redundant implementation with two encoders. With the help of the Safety-M
safety module the safe overall controller has become a safe compact controller, where many
components can be dispensed with; this is thus an important factor when looking into cutting
costs.
No need to be afraid of Safety
O ne argument against safety controllers, which occurs at regular intervals in discussions
with wind turbine manufacturers, is that on balance they feel that safety technology can have
a negative effect on the availability of the turbine. Concerns here regarding extensive
regulation and reforms can easily be laid to rest, as the worries are unfounded. The primary
task of safety technology is to monitor unsafe conditions, as well as to protect both people
and machines. If the safety controller operates too frequently, then there is something wrong
with the configuration of the safety levels. Then problems can arise in the system. The
Safety-M customized total solution offers fast access to a suitable safety solution for special
areas of use. The modules can be easily expanded and can be integrated in a user-friendly
manner into each and every standard control environment, eliminating the problem of toofrequent
switching.
The safe Total Solution: interaction guaranteed
The fear that safety technology will generate additional costs for the wind turbine also soon
shows itself to b e incorrect, thanks to the Kübler solution of safety module and encoder.
Quite the opposite: when correctly installed, safety technology can eliminate the need both
for redundant encoders as well as redundant evaluation systems, thus helping reduce costs.
When equipping a plant with safety technology, it is not just a matter of individual
components, but more importantly how they work together. The Safety-M modules are a
tried-and-tested perfect match to the Sendix SIL-encoders. The user does not need to
plough through datasheets or study lengthy test reports to be sure that the components he
has selected will actually work together smoothly and without problems. Sourcing both the
encoders and the monitoring unit as a set from the same supplier guarantees that the
components have been optimally matched to each other. So nothing therefore stands in the
way of simple implementation – and much potential remains for savings to be made. Happily
this is not just measured in figures, as there is also increased safety for the operator that
offers further cost savings, even if these can be somewhat difficult to calculate. Nevertheless
it is easy to quantify the savings that such a total solution brings with it, especially when it
comes to project planning, construction, documentation, purchasing, installation and last but
not least by the simplified TÜV and GL certification of the wind turbine itself.