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A microwind turbine in operation in Elgoibar

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Since last October, the four refrigerators of the Basque centre Aubixa de Elgoibar are powered by renewable energy. In fact, the company Fatronik has installed there the prototype of the microwind turbine designed by itself. It has launched a hybrid system: a microwind turbine and four photovoltaic plates. The expected power is 9.6 kWh a day and, if the test yields good results, the prototype will be put on sale in the short term. Technical data: Microwind turbine installed by Fatronik in Elgoibar. It is observed that it is quite smaller than the conventional wind turbine. (Photo: Fatronik Foundation).

The name gives the biggest track. A microwind turbine is a small wind turbine, of the same base as traditional giants, but much smaller. It has a height of 30 meters and just ten meters, and instead of having blades of fifteen meters, it has two meters. Of course, it produces less energy, but it also has less environmental impact. Its aesthetic impact on the landscape is low and practically harmless to birds and wildlife. In addition, they are easier to install and maintain.

Power grid replacement

The system that has been launched in Elgoibar is not at all a substitute or competitor for high-power wind turbines. Its aim is to replace the power grid in areas where the transmission cost is too high. Such systems are very appropriate, for example, for those people who live far from urban, rural or developing areas. They offer the possibility of having electricity and at the same time guarantee a sustainable development of the territory.

In this case, the system simultaneously exploits two renewable sources: wind and sun, that is, a hybrid system. Hybridization is not a constant in these areas. Despite the proliferation of wind farms in a few years, the installation of photovoltaic plates for overboard lighting has caused the installation of a wind turbine next to the house to pass through the head a few. Currently, this technology has the main producers and users in the United States, although it is gradually spreading in Europe and Spain.

Microwind Generator Features

The biggest difficulties have been the design of a system of protection against excessive speed. (Photo: Fatronik Foundation).

The wind turbine designed by Fatronik has a power of 2.5 kW and consists of three fins of 2.1 meters each. The blades have a variable torsion angle from root to end, so the angle of incidence with the slope of the wind remains constant along its entire length. The wind turbine starts turning at an approximate wind speed of 3.5 m/s, reaching an approximate speed of 9.5 m/s the nominal power of 2.5 kW. In addition, it can rotate freely depending on the wind direction, i.e. it can rotate 360º as a compass.

To this point, the assembly of the prototype has not meant a headache. The greatest difficulties have been the design of the system of protection against excessive speed, where Fatronik has made his greatest contributions.

The protection system is a passive system based on the mechanical design and freedom of rotation of the microwind turbine. The problem is that thanks to these characteristics the wind turbine moves so that the wind force is avoided. Instead of placing the microwind turbine to the wind side, it is placed to the other side, thus decreasing the speed of the rotor.

The Aubixa plant is a hybrid system with a microwind turbine and four photovoltaic plates. (Photo: Fatronik Foundation).

This turning braking protects the system from electrical and mechanical overloads. When the wind exceeds a certain speed, about 16 m/s, the power control system of the wind turbine is automatically put into operation. For passive control design, Fatronik has used the ProMotion module of the Pro Engineer program and, in the dynamic simulations carried out, the appropriate values of the main parameters and variables have been resolved to ensure proper demolition speed and stable operation.

System control

The microwind turbine launched at the barnetegi Aubixa will spend a few months in the validation phase. During this period, the main orientation parameters of the wind turbine will be measured to know and analyze the precision, the minimum wind speed that modifies the rotor orientation and the exact activation of the braking manoeuvre.

All these data are transferred from localized sensors to Fatronik headquarters using the GPRS remote control system. These equipment also includes wind speed and direction data, as well as power control data generated or absorbed.

During the evaluation phase, the electricity needed for control management will be taken from the one provided by the system itself, so in the barnetegi only refrigerators will have a renewable energy source. However, keep in mind that such a system can produce the energy a home needs.

Rated power: 2.5 kW rated wind speed: 9.5 m/s Generator: permanent magnets (PMG) Diameter: 4.5 m Height: 10 m Orientation: passive (tail vane) Power control: passive (side furling)