GE Power Conversion has been selected to equip Verbund’s new fully fed pump storage power plant Resseck II+ to be located between the two reservoirs Grosser Mühldorfer See and Kleiner Mühldorfer See in Kärnten, both at 2300 metres above sea level.
Reisseck II+ will be an underground cavern power plant and an efficient extension to the Reisseck II pump storage unit, which went into operation in 2016. The combined Malta-Reisseck water group in Kärnten has a total power rating of 1460 MW and is one of the most powerful hydropower plant groups in Austria.
For the new Reiseck II+, Verbund is planning to build up a variable-speed machine set with a motor in full converter technology and two single-stage, double-flow pump turbines with a total power of 45 MW. For this project, GE will deliver three MV7616 converters, which are water cooled fully fed units running at 6.6 kV. GE will also supply a control unit, an excitation unit integrated in the converter control, and an excitation transformer. This project is being implemented with GE Renewable Energy which will manufacture the motor/generator. The pumped storage power plant is scheduled to be put into operation by the end of 2023.
The special feature of this project is the easy controllable machine set, which uses almost the entire drop/delivery height variance of two storage tanks, that is, between 16m and 124m with a maximum flow rate of 55m³/s and a maximum output of 45 MW. The nominal speed is 500 rpm, with speed variance of 250 rpm to 550 rpm. It is due to these unfavourable boundary conditions that this unconventional machine set was designed. It allows one of the two units to halve the output by dewatering with gap sprinkling.
This is GE Power Conversion’s second project with Verbund in recent years. In 2018, the two companies started the project Kaprun Oberstufe with the modernisation of two machine groups each of them 85 MW fully fed. Currently, the first machine group is under wet commissioning and the installation for the second machine group will start in the middle of 2021.