SGB-SMIT contribute to FASTAP with a cast resin dry type transformer

Unlike existing solutions, the voltage in FASTAP’s wind turbine transformer is not adjusted with mechanical or regulating switches, but with the help of semiconductor technology, so-called thyristors. The main advantage of this solutions are fast switching processes even at relatively high frequency. Extremely high number of switching operations until maintenance or wear (>50 K endurance).

This is not only, but especially interesting for wind energy. Until now, wind turbine transformers have been set to a fixed voltage value. In the event of grid fluctuations, operation had to be adjusted or restricted accordingly. With the new voltage regulation directly at the transformer in the wind turbines, the profit can be improved in existing parks. For new parks, FASTAP can reduce investment costs while in parallel maintaining or increasing performance.

In order to be able to carry out the necessary tests on the FASTAP turbine prototypes, the test field at the University of Mondragon is being converted and expanded for this project. The transformer shown in the picture is, besides the turbine prototypes, an important project contribution of SGB-SMIT, Cast Resin in Regensburg for the equipment of the test field in Mondragon.

It is a cast resin dry type transformer. The power of this transformer during the test is approx. 7.4 MVA, the weight approx. 19 t and with following dimensions of approx. 4 x 2 x 3 meters. The transformer can be adjusted to several main voltage levels (30/20/15kV) to simulate different medium voltage networks.

In the main levels, however, it can be regulated more finely to simulate grid behaviour and grid faults. Also, here the fine voltage regulation is realized via thyristors, as it is the case with transformers in wind turbines.

Unfortunately, the thyristors were not available at SGB-SMIT at the time of delivery. As with many products at the moment, there were delivery problems due to material availability.

The development took one year, completed in mid-October 2022 and the delivery to Spain took place at the beginning of November 2022. Once in Spain, the transformer will be retrofitted with the thyristors on site and integrated into the university’s test field by the end of November 2022. Operation, testing and trials will start at the beginning of 2023