GE Variable speed full size MM7

PSPP Linthal (Switzerland)

The PSPP Linthal was commissioned and handed over to

operator AXPO in 2016 and is producing energy since then.

The 1000MW PSPP is one of the most advanced

hydroelectric power plants in the world.

It is equipped with four rotating machines of 250MW each.

where the decision was taken to use the variable speed

technology to improve operation behaviors and increase the

advantages in regard of efficiency in full load and especially

the significant improvement in part load operation.

Power Conversion’s scope includes:

• Four 48/48MVA converters for the variable speed asynchronous machines

• Four excitation transformers 18/3.0kV; 28MVA

• Control excitation equipment to start-up the machine and synchronize the

units to the grid

• Overvoltage control protection (crowbar) for rotor of the machine

• Low voltage ride through (LVRT) ability according to Swiss grid code

PSPP Kaprun / Oberstufe Limberg I (Austria)

The PSPP Kaprun Oberstufe was originally commissioned

1955-1956 with two horizontal machines sets consisting

of Francis turbine, motor-generator and a two-stage radial

pump. The overall installed power of this power plant was 112MW.

In 2018 the modernisation started. To increase the efficiency

and adapt on the new requirements of the energy market, the

Verbund decided to modernize the existing pumped storage

station Kaprun Oberstufe. In 2017 the tendering process for

both machine groups started. They shall be equipped as a

variable speed application with fully fed technology consists

of pump turbine, motor-generator as synchronous machine

and frequency converter. The converter is located between

synchronous machine and main step-up transformer and is

feeding the energy to the grid in turbine mode. Since mid of

2021 the first machine group is now producing energy and

one year later mid of 2022 the second machine group is

connected to grid as well.

Power Conversion’s scope includes:

• Four 6.6kV converters in sum 80MVA for the variable speed synchronous machines

• Main step-up transformers 110/6.4kV; 85MVA

• Control excitation equipment to start-up the machine and synchronize the units to the grid

• SEE units for the synchronous machines

• Overvoltage control protection

• Low voltage ride through (LVRT) ability according to Austrian grid code