Large-scale pumped storage in Switzerland

ABB is supplying a complete package of electrical equipment for the new 1,000 MW Limmern pumped storage power plant in Switzerland. Kraftwerke Lint-Limmern (KLL), a member of the Swiss power producer AXPO, is overseeing the project, with the first unit expected to be operational by 2015.

Pumped storage power plants are an efficient means of large-scale energy storage, and an important par t of the strategy to add renewable energy such as wind and solar generation to the power mix, because they can quickly balance power fluctuations caused by sudden wind gusts or cloud cover.

The Limmern pumped storage hydropower station is being installed in an underground cavern. It will have four generating units with a total capacity of 1,000 MW in generating and pumping mode. Each unit consists of a pump-turbine and a doubly-fed asynchronous motor/generator, allowing them to operate with variable speed and enhancing the plant’s overall per formance.

In generation mode water will flow from the upper reservoir, Muttsee, 600 m down to the generation units and further on into the lower reservoir, Limmernsee. From there it will be pumped back up again for storage and released when needed.

ABB is providing electrical equipment and a control system based not only on price and technical characteristics, but also on outstanding references and experience in comparable projects, specif ically in control systems for large-scale pumped storage plants. ABB's responsibility extends from design to engineering, manufacturing, delivery and commissioning of components and systems.

The equipment list from ABB includes main and auxiliary transformers, medium- and low-voltage switchgear, instrumentation and automation systems. ABB will also provide a 380 kilovolt (kV) GIS (gasinsulated switchgear) substation to feed power from the plant to the Swiss national grid.

The finished plant will help KLL generate clean energy to meet future peak load and ancillary services demand across Switzerland, contributing to the stable operation of an interconnected European grid.

In addition to operating efficiency, technical solutions, terms, conditions and references, a key factor in ABB winning this contract was its ability to demonstrate how the new plant could be seamlessly integrated into the existing infrastructure - a mat ter of great impor tance for KLL, says Emil Bieri, Axpo Power AG's project manager in charge of electrical. A reference visit to a similar ABB pumped storage installation in Austria helped seal the deal.

Kraftwerke Linth-Limmern AG (KLL) is a joint venture between Canton Glarus (15%) and Axpo Power AG (85%). KLL generates about 480 MW of power from four existing hydropower plants. The expansion project Linthal 2015 will add another 1,000 MW of pumped storage capacity to secure the efficient and flexible operation of KLL’s assets.

Approximately $2 billion will be invested until 2016, the year the plant will reach full operational capacity. Up to 500 people will be working on site during its construction. The project area encompasses different sites at altitudes between 800 and 2,400 meters above sea level (MASL), which is a logistical challenge. Two new high capacity transport ropeways had to be built, capable of carrying up to 40 tons of equipment.

The 4-km long access tunnel has been excavated by means of a tunnel boring machine (TBM), weighing about 1,600 tons, measuring 160 m in length and with a drill head diameter of 8 m. Never before has a TBM of that size been used in a tunnel with up to 24 degrees incline. When completed, the access tunnel will be equipped with a 200-ton funicular, for transporting heavy equipment to the power cavern (including the four main transformers).

About 500,000 tons of rock, from the excavation of the tunnels and the power cavern, will be used for a new gravity dam that increases the storage capacity of the existing Muttsee (upper reservoir) from 9 to 24 million m³.

Main data

Application: Hydro power plant
Capacity: 1000 MW
Technology: EBoP
Geographical location: Europe / Switzerland
Year of commissioning: 2016

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