From September 6 to 8, the HSZG visited Kraftwerke Oberhasli AG (KWO) on behalf of Prof. Uwe Schmidt and Jonathan Hänsch from the EI faculty. The destination of the trip was the Grimsel 2 pumped storage power plant, in whose modern 245 kV switchgear various measurements were carried out. The purpose of the measurements was to investigate transient processes when the machines are switched on.

The Grimsel 2 power plant has four machine groups with a total output of 344 MW for generator operation and 363 MW for pump operation. It was built between 1973 and 1980 and is located in the southern part of Switzerland.

Pumped storage power plants are fundamentally important components of the electricity grid as they are able to store large amounts of energy. They can also react within minutes to changes in transmission grid requirements. Due to their characteristics, they contribute to the stabilization of the European power grid. The Alpine region provides ideal conditions for hydroelectric power plants and pumped storage power plants.

The 245 kV switchgear of the power plant is designed as a gas-insulated switchgear (GIS). The very compact design of a gas-insulated switchgear is a decisive advantage when used in a cavern power plant. A pressurized gas, usually SF6, is used as the insulation medium. The switchgear connects the individual machines of the power plant with the transmission grid of Swissgrid AG, the Swiss transmission grid operator.