Darwind - Model XV90-2MW -Onshore Turbine

Besides the known permanent magnet direct drive benefits; this turbine excels in LVRT, low voltage ride through. The sealed nacelle makes it suitable for working onshore, near shore or on inland desert and mountain locations.

The turbine is designed according to IEC 61400 for a wind class IIIA , defined by an annual average windspeed of 7.5 m/s at hub height and an effective turbulence level of 16%. The design (technical) lifetime is 20 years.

Darwind uses the philosophy of horizontal integration what means all manufacturing is outsourced and we only assemble and test before sending the turbine to site. All design work however is done in house and in conjunction with strategic suppliers for components such as blades, bearings, hydraulic systems, towers and pitch system. In this sense we are a system integrator although the majority of the components are of exclusive design.  

All intellectual property rights of the XD115 turbine are vested in XEMC Darwind B.V. (Netherlands). To date no license rights have been granted to third parties. To protect XEMC Darwind’s unique position over 20 patents are pending.  

XEMC turbines are based upon the single bearing, direct drive, and permanent magnet principle.

Structural design

Use is made of a single multiple row roller bearing on which the hub is mounted on one side and generator carrier and –rotor on the other side. The stator is mounted on the opposite side of the carrier which in turn is mounted on a compact casted nacelle frame. The advantage of this design is the relative big diameter the load path follows, contrary to the traditional designs with a main shaft. Hence considerable weight reduction is achieved.  

Innovative design and new materials have resulted in an easy to install, large, lightweight turbines.  

Our product platform is based on the direct drive principle, thereby dispensing of the need for gearboxes. Gearboxes pose a significant problem for offshore wind turbines because the torque of multi-megawatt wind turbines is enormous. In contrast, gearless turbines require less maintenance, are more reliable and therefore boast higher operating availability.

The rotor speed during power production is variable. The matching between the available aerodynamic torque and the produced electromechanical torque of the generator is determining the rotor speed. No use of a gearbox is made. The torque-speed curve is programmed in the frequency converter controller and the inverter is adapting the generator stator current in response to the measured generator power frequency.  

The XEMC Darwind XD and XE platform is based on the single main bearing concept. The bearing has a large diameter that enables it to bear the enormous force of the rotor: there is no central shaft. The bearing component is integrated into the generator and is possible because the turbine uses direct-drive technology. This innovative design not only creates a compact and lightweight permanent magnet direct-drive generator; it also results in significant savings in logistics, foundation and support structure costs.  

The tower and nacelle of the turbine are fully sealed to keep out the salty and moist sea air. This protects our valuable components, increases operational availability and saves a great deal of maintenance.  

Coil driven generators make use of electrical excited magnets. XEMC’s Permanent Magnetic systems are lighter/compacter, more efficient and require less copper than Coil Driven generators. As no additional electricity is required to magnetise the rotor coils, there is no need for generator `brushes` to transfer this electricity. This increases both efficiency and reliability because the rotating part of the generator contains no electrical systems.  

The AC-DC-AC converter, located in the bottom tower section, allows the generator to operate with a variable speed while the power is fed into the grid with a constant frequency of 50 Hz (or 60 Hz for the countries where this applies). It furthermore assures an average constant power output for wind speeds above rated. The power factor at the grid side is controllable at standstill as well as in operating mode. Above rated wind speed, the blade pitch control maintains a more or less constant rotor speed between admitted boundaries.  

XEMC wind turbines have a pitch-controlled variable speed rotor and a full power converter, capable of meeting the requirements of the most demanding grid codes, e.g. with respect to reactive power.