Generation without transformers: introducing Powerformer

25 March 1998

ABB is claiming a breakthrough with what it describes as the "world's first high-voltage generator". Called the PowerformerTM, it was launched in Zurich on 25 February and is said to be the first generator able to supply electricity directly to the high voltage network without the need for intervening transformers.

Powerformer can generate electricity at voltages between 20 kV and 400 kV. A prototype with a rating of 45 kV is scheduled to be operating in May/June this year at the Porjus hydropower plant on the Lule River in northern Sweden. This plant is owned and operated by the Foundation Porjus Hydro Center, which is run jointly by Swedish utility Vattenfall, Kvaerner Turbin and ABB and serves as a development and training facility for hydropower technology.

According to ABB President and CEO, Göran Lindahl, Powerformer "radically changes a 100-year old technology and establishes a new class of rotating electric machines" – providing increased efficiency, better economics and environmental benefits. An increase in overall efficiency of more than one per cent is expected, as well as lower total investment costs and lower maintenance costs.

In the new generator, round high voltage cables, using proven XLPE insulation technology, replace the complex structure of square-section insulated copper conductors that constitute the stator winding of a conventional generator. Powerformer can be sized to produce any output voltage. Step-up power transformers, with their associated cooling, are therefore no longer needed. High voltage connections are simplified and the layout can be made more compact – important where space is scarce, for example underground.

Another advantage claimed for the new design of generator is that it has a positive influence on the power grid by producing more reactive power and creating greater network stability than conventional technology. It is also better able to handle short-term power overload demands.

ABB believes that the new technology not only promises major benefits for power system designers but also is widely applicable to the retrofit and upgrade of older generators in existing plants. Kjell Isaksson, chairman of Porjus Hydro Power Center and technical director at Vattenfall, believes "It is of particular interest for those having generating units in the 40 to 50 year age bracket".

He reports calculations made by Vattenfall which assume a one per cent increase in efficiency, a ten per cent decrease in investment costs and significantly reduced O&M costs. These project savings of $125 million over 30 years for Vattenfall's existing hydro capacity or $250 million for Sweden's total hydro installed capacity.

The innovation is a tangible benefit from ABB's investment in R&D, which currently runs at about eight per cent of revenue (amounting to $2.7 billion in 1997).

Powerformer's inventor, Mats Leijon, manager, Department of High Voltage Engineering, ABB Corporate Research, Västerås, Sweden, started pursuing the concept of a cable-wound generator stator at the beginning of the 1990s. "I'm convinced that my ideas will change the entire energy market," he says.

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