Drives and Controls Magazine

Drives play key role in rooftop turbine

16 October, 2009

Parker Hannifin’s SSD Drives division is supplying power conversion systems and generators for a new rooftop-mounting wind turbine which “amplifies” the incoming wind to produce as much power as conventional turbines three times larger.

The 60kW WindCube (shown above during installation), developed by US-based Green Energy Technologies (GET), is designed to generate power for commercial and industrial users. A “shroud” funnels the wind into the five-bladed turbine and increases the windspeed in accordance with the Bernoulli principle. This allows the turbine to generate power in windspeeds as low as 5mph (2.2m/s).

GET says that the 5m-diameter turbine produces the same output as a conventional turbine 15m in diameter. With an average windspeed of 7m/s, the WindCube will produce about 160MWh a year. With the rebates and tax incentives available in the US, the $250,000–300,000 turbine can pay for itself in three years, GET adds.

The control system provided by Parker includes a main AC890 grid-tie inverter, which feeds AC power directly into a building’s power network, and a smaller AC890 motor drive for the yaw mechanism that points the turbine into the wind (or turns it away from the wind in speeds above 17.9m/s). Both devices communicate with a touchscreen HMI via Ethernet. Parker is also providing the permanent magnet AC generator and the servomotor for the yaw mechanism.

The WindCube blades drive the generator directly, avoiding the need for a gearbox – the most common source of maintenance problems and failures on conventional wind turbines. There are redundant brakes for high winds and maintenance, which are monitored by an on-board PLC and can be controlled remotely.

The WindCube turbine – which measures 6.7 x 6.7 x 3.6m – is available in single (60kW) or dual (120kW) versions, for mounting on rooftops or on towers.

♦  Parker Hannifin has set up a dedicated European team of technical and applications experts to develop customised systems for wind and wave energy applications. The company already supplies products from its pneumatics, hydraulics, VSD, sealing and condition-monitoring portfolios for renewable energy applications. It has recently been developing systems for wave power generators using its VSD and hydraulic technologies.