Nominal rating for the four existing models has been raised from 3.3MW to 3.45MW, and they have been upgraded in terms of IEC Class too. With the recent announcement of V136-3.45MW low-wind model, the series now comprises five rotor variants, two nacelle/gearbox configurations, and a choice of 15 hub heights.
The platform evolution involves structural upgrades, an optimised industrial converter, a high-torque gearbox for the V136-3.45MW, and a low-noise version of the V126-3.45MW.
One reason for the development of two gearbox variants is to better manage the slower turning speeds of large rotors for aerodynamic noise-curbing, thus raising rotor torque for a given rating.
The new low-noise V126 model has a relatively small rotor, but is likely to operate at reduced rotor and tip speeds.
The upgrade means that all models now feature the same nacelle layout and dimensions.
Vestas' experience of 3MW-class turbine dates back to 2003 with the launch of the lightweight V90-3.0MW, which featured a compact high-speed drivetain with doubly-fed induction generator (DFIG) and semi-integrated single rotor bearing.
That model is still available, but Vestas has since switched to a non-integrated high-speed drivetrain for its 3MW series. This was first seen in 2010 with the introduction of the V112-3.0MW model, which featured a 112-metre rotor diameter and a permanent magnet generator (PMG) with full converter.
During 2012-13 the series was expanded with the introduction of the V117 and V126, while nominal rating grew to 3.3MW, and induction type generators were used in place of PMGs.
With an optional 'power mode', output could be boosted to 3.45MW for favourable site-specific conditions, such as a low wind turbulence level.
The uprated V117 model is now available for IEC I high-wind sites and the V126 for IEC II medium-wind sites.
A 3.6MW 'power mode' is optional for the V105, V112, and V117. First deliveries of these four models are planned for Q4 2016, and in Q3 2017 for the V136.
An innovation aimed specifically at the German market is a type-certified large diameter steel tower (LDST), which in combination with the V126 models offers a 229-metre installation tip height.
Interesting for the offshore segment is that MHI Vestas earlier this year announced tests on V117-3.45MW turbines aimed at "further improving the performance of the 3MW platform". It seems evident the V117 will soon succeed the V112 model provided testing proves positive.
This, in turn, offers MHI Vestas clients potential for higher annual energy production (AEP) and lower levelised cost of energy (LCOE).