Some research projects for the the future will consist of testing and evaluating rotor projects. In addition, they will also involve gathering baseline data on turbine interactions.
This data can be used by the international community and Renewable Electricity Supplier to improve the performance of wind farms. Similarly, the rotor project will serve to propose a rotor architecture. The data will be freely accessible on an open-source model to allow industry players to collaborate more easily and thus accelerate technology transfer to markets.
Although the vast majority of wind turbines installed today in New Zealand are three-bladed wind turbines with a horizontal axis for an average unit power of 2 to 3 megawatts (MW), the spectrum of the main technologies of the sector is wider.
Asynchronous or synchronous turbines
The turbines currently on the market are divided into two main categories according to the architecture of their electric generator: those equipped with an asynchronous generator (about 75 percent of the market), and those equipped with a synchronous generator (about 25 percent of the market).
Asynchronous turbines are used in most cases because they can withstand slight variations in wind speed, especially during gusts. These speed variations generate significant mechanical stress on the system, which are reduced with an asynchronous machine.
The synchronous turbine involves a direct mechanical drive between the wind turbine hub and the generator. The advantage of this technology is to offer machines with fewer rotating parts which simplifies maintenance.
Horizontal axis wind turbines are by far the most widespread. Other configurations are possible: these are vertical axis wind turbines, as is the case with Savonius or Darrieus type wind turbines.
Consisting of half-cylinders connected to a vertical axis, this type of wind turbine uses the wind drag force, on the principle of windmills. Its performance is lower than that of horizontal axis wind turbines, but this type of machine can exploit lower wind speeds. Small in size and quieter than other wind turbines, Savonius type wind turbines have been studied for integration in urban areas but are struggling to find their place because of their very high electricity production cost.
With vertical, parabolic or helical blades, Darrieus wind turbines use the wind lift force, like conventional wind turbines. However, their smaller footprint is an advantage in terms of landscape and architectural integration.
Most wind turbines are 3-blade wind turbines with a horizontal axis. This choice is essentially due to a compromise between the efficiency of the wind turbine, its operating constraints and its manufacturing costs.