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Customer Success Story

Unlocking wind energy in the Alps

Special transformer for Europe’s highest windfarm

One of the Swiss government’s goals is to harness potential wind, solar and hydropower resources at the country’s higher elevations, in order to make surrounding areas more energy self-sufficient and less reliant on fossil fuels.

In support of this ambition SwissWinds Development GmbH (SWD), a Swiss contractor that specializes in developing high-elevation wind parks, has launched a unique renewable energy project that connects wind and hydro generation to the regional power grid in the rugged, mountainous Valais region.

At 2,465 meters above sea level the site is the highest wind project in Europe, and Hitachi Energy’s contribution as a key partner is the design, delivery and installation of a custom-built, small power transformer. SWD plans to merge the production of a four-turbine wind power plant with an existing hydropower station.

Hitachi Energy’s special 3-winding small power transformer replaces part of the original hydropower infrastructure, and features lower losses to optimize total cost-of-ownership; seismic protection; and a compact Oil Forced Water Forced (OFWF) cooling system based on heat exchangers utilizing the ever-present cold hydro reservoir water.

Hitachi Energy’s solution is as compact as the original unit to minimize modifications to the existing transformer chamber. Not only can it be delivered through the same narrow tunnel as the original 50-year-old hydro transformer, the Hitachi Energy unit provides twice the power capacity, enabling it to inject power into the local grid from both the old hydro plant and the new wind farm.

Hitachi Energy’s transformer solution was delivered in just six months to meet a short, three-month installation window before snow and bad weather interrupted work.  

Officially inaugurated on September 30, 2016, the Griessee wind project is expected to generate about 14 million kilowatt hours (kWh) of electricity annually, enough to meet the needs of 3,000 Swiss households.

Main data
Customer SwissWinds Development GmbH (SWD)


Special transformer


Wind farm

Power rating

20/10/10 MVA, 66(±2x1.3)/20/5 kV 


Gries, Switzerland          

Delivery date

July 2016


August 2016