Secure electricity supply despite replacing the transformer: two new transformers for the Schärding-Neuhaus power plant


Two new transformers were built in at the Schärding-Neuhaus marginal plant and at the same time, the medium-voltage switchgear was renovated. In this way, clean electricity from hydropower can also be delivered unhindered in the next decades to Bavaria and Upper Austria's companies and households.

In the last months, two high-voltage transformers were replaced in the 220kV outdoor substation in the marginal power plant of Schärding-Neuhaus. The delivery of the second transformer, which weighed over 155 tons, took place overnight from the 19 to 20 September from the power plant in Regensburg and was installed this morning. The electricity could continue to be produced uninterruptedly while the flexible replacement took place, the new transformers will be able to provide a securer electricity supply in the next decades.

The two old transformers, which have been in operation since the construction of the power plant at the start of the 1960s, have reached the end of the road. In order to achieve a securer electricity supply, the marginal power plant in Schärding-Neuhaus replaced the first transformer in 2013 and now the second one in September 2014. Additionally, the 10kV medium-voltage system was repaired. 

Transporting the second transformer was also rather spectacular, as the piece, which weighs over 155 tons, could only be hoisted into place using special lifting techniques and a provisional track. Following installation, extensive alterations and testing will be necessary in the coming days so that the new transformer can be able to feed electricity into the grid at the end of October 2014. "The new transformers possess a better level of efficiency, which can lead to a lower no-load loss and loss of load. Thanks to modern material, a reduction in the total loss in the full load could be cut down to half" says Project Manager Johannes Thalmhammer from the marginal power plant. "The output per transformer is 110 MVA, the voltage is 230 kV/10.5 kV with a total weight of 155 tons".

Flexible Renovation for Securer Electricity Supply

At the same time as the replacement of the transformers takes place, the pneumatic medium-voltage system will be repaired; it dates back to the time the plant was constructed. The age and the open construction method made it necessary to renovate the plant, since it is needed to transport the electricity produced by the four machine units. Due to the high constant current of 6,300 amperes and respectively the short-circuit current of more than 63,000 amperes, a special design had to be built in. The medium-voltage system was planned and carried out using compartments and pressure relief channels, taking current norms and regulations into consideration. This medium-voltage system is in line with state of the art technology in regards to personnel safety and equipment availability. As an accompanying project, the electricity power rails to the new transformers were completely renovated. Here interfaces and appointments had to be agreed upon, seeing as, for example, the transformers on the low-voltage side will be directly connected to the medium-voltage system, says Project Manager Hans-Peter Wagner of the medium-voltage system.

The Hydroelectric Power Plant in Schärding-Neuhaus

The VERBUND power plant in Schärding-Neuhaus is a run-of-river power plant on the river Inn located in the municipalities of St. Florian bei Schärding in Upper Austria as well in Neuhaus in Bavaria. The marginal power plant in Schärding-Neuhaus was the second power plant to be built by the Österreichisch-Bayerische-Kraftwerke AG from 1959 to 1961. The weir and the power plant were installed in a line, perpendicular to the river axis. The weir facility lies on the Bavarian side of the river and the powerhouse on the Upper Austrian side. This powerhouse was also built without superstructure work as is the usual construction method on the river Inn. In the power plant, four Kaplan turbines with vertical shafts have been installed. There is a three-phase synchronous generator directly on each of the turbine shafts. In this way, per year, around 542 GWh of electricity are generated.

Through the construction of the power plant and the back water area, unique new habitats for flora and fauna could be created via the water surfaces and the newly emerged silt areas. On the Austrian and Bavarian sides, a spacious bird paradise has sprung up between Reichersberg, the Antiesen estuary and Bad Füssing, in which rare bird species like the black-crowned night heron, purple heron, the little bittern and the northern pintail have found a new home.

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