Simplified schema of a standard wind turbine. The multiplier gearbox is heavier and bigger than the generator. With the new superconducting generator, the multiplier gearbox could be smaller and lighter.Superconductors are materials without electrical resistance, therefore they can transport electricity without losses. Also, in the field of electric power generation, superconductors configure promising alternatives.
To make progress in this area is the goal of a project developed by Gamesa Innovation and Technology, a leading Spanish technology company in the wind energy industry, together with the Institute of Materials Science of Barcelona (ICMAB) of the CSIC and the Institute of Materials Science of Aragón (ICMA), a joint centre of the CSIC and the University of Zaragoza.
The project, partially funded by the Spanish Ministry of Economy and Competitiveness (Retos Colaboración RTC-2014-1740-3), has successfully completed the first phase with the first prototype of a medium speed superconducting generator to be used in conventional medium power wind turbines (2 MW).
The generator developed is lighter than a conventional one and can achieve the same or more power with a slower rotation speed (a third of the usual), thus reducing the mechanical effort that the multiplier gearbox has to make –the multiplier is the mechanism which increases the speed of the movement from the blades and transmit it to the generator. Combined, this makes it possible to reduce the weight and to simplify the structure of the whole mechanism.
The generator is lighter than a conventional one and can achieve the same or more power with a slower rotation speed
This is a critical point of the turbine winds, as scientists of the project explain. The gears of the speed multiplier have to resist strong mechanical effort. The slower the rotation speed, the fewer the amount of gears and the lighter the weight. As a result, the mechanical effort is smaller as well as the inertia, and the risk of breakdowns and technical disruptions is reduced.
The prototype during the tests in the laboratory. In addition, the generator doesn’t have iron in the magnetic circuit and uses less copper than conventional generators, which allows it a greater efficiency and, consequently, a much lower generation of heat dissipation. Therefore it drastically reduces cooling requirements.
The advantages of this new type of electric generator that uses superconducting materials compared to the conventional generators are diverse: it simplifies the entire mechanical structure of the wind turbine as well as the electronic system; simplifies the assembly and maintenance. The breakdown risk is also diminished; the time of intervention for maintenance is extended; and, in the near future, the cost will be reduced according to the rapid evolution of superconducting materials.
The future implementation of this type of electric superconducting generator in the wind turbines opens a new perspective to the wind energy industry, making windmills more efficient and robust and so reducing the costs of energy production.
After four years of collaboration between the three entities, the culmination of the first phase of the project with the successful construction of this prototype and the corresponding trials has become a successful case of technology transfer.
The scientists and the company Gamesa continue collaborating in order to carry out field trials to offer new innovative technological solutions in this sector.