A French company has developed a new type of compact wind turbine that is claimed to produce as much electricity from a unit that is just 1.5m in diameter as would be produced by a conventional wind turbine 6m in diameter.
The TurboWind turbines from Elena Energie of Grenoble in France comprise a patented hull or casing that encloses two sets of rotor blades and a spoiler. The hull works in conjunction with the rotor blades and the spoiler to increase the speed of the airflow. For example, a wind speed of 6m/s produces airflow of 15m/s at the second set of rotor blades.
The two sets of rotor blades rotate in opposite directions. The profiles of the rotor blades have been designed specifically to ensure smooth airflow, and the operating mode of the rotors is determined by a sophisticated electronic control system.
When the turbine is in operation, the wind speed is measured by an anemometer and the control system continuously analyses the torque that will be transmitted to the rotor blades by the available airflow. In light winds, the first rotor is used to boost the speed of the air reaching the second rotor. This, says Elenia, allows the TurboWind Elena turbine to begin producing useful amounts of electricity at lower wind speeds than is possible with conventional windturbines.
At intermediate wind speeds, the first rotor rotates freely so as not to disturb the flow of air to the second rotor, which means that energy production is once again optimised. At high wind speeds, the first rotor only drives the generator, allowing the TurboWind Elena to continue producing electricity under conditions that would require ordinary wind turbines to be shut down to ensure safety.
As a result of these operating modes, the TurboWind Elena reaches maximum output more quickly than conventional designs and maintains this output over a much wider range of wind speeds. A further important benefit is that it is much quieter in operation than ordinary wind turbines, which makes it well suited for applications in and close to residential areas.
Elena approached Warwickshire-based Parker to meet the generator requirements of the project. Parker proposed a customised version of its NB8 double generator and to interface the output of the generator to the electricity supply network, two of the company’s modular AC890 inverter drives were proposed.
The AC890 inverters find their main application in the control of large motors.However, they feature a power platform and control algorithm that allows them to combine reliability with ease of use in power generation applications with both induction and permanent magnet AC generators. In these applications the inverters take the variable output of the generator and convert it, with minimal losses, to an output at a stable voltage and precisely controlled frequency, which is suitable for connection to the electricity transmission grid.
Engineers from Parker worked closely with their counterparts from Elena Energy to ensure that the generators and inverters were fully optimised for the Turbowind application. After testing of the turbine itself and its associated components, the first TurboWind system was recently installed and commissioned at a water bottling plant in Haute Savoie in France. Elena said the installation had attracted a high level of interest from public bodies, commercial organisations and even potential domestic users.