HIGH VOLTAGE GENERATORS
Have you heard of a generator at 400 kV? Sounds fantastic, but ABB broke through with world's first high-voltage generator… 10 years ago! The first unit was installed in a Swedish power plant in 1998.
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Have you heard of a generator at 400 kV? Sounds fantastic, but ABB broke through with world's first high-voltage generator… 10 years ago! The first unit was installed in a Swedish power plant in 1998.
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In an Internet article dated February 25, 1998 released in Zurich, Switzerland, ABB, the international electrical engineering company, presented the world’s first high-voltage generator. Called the Powerformer, it was the first generator able to supply electricity directly to the high-voltage network, without the need for transformers.
The Powerformer can generate electricity at voltages between 30 kV and 400 kV. The first operational generator, with a rating of 45 kV, 11 MVA at 600 rpm, was successfully installed at a power plant in northern Sweden owned and operated by the Foundation Porjus Hydro Centre. The Center, which serves as a development and training facility for hydro power technology, is run by the Swedish energy company Vattenfall, Kvaerner Turbin and ABB.
HISTORY OF POWERFORMER
Today’s high-voltage generators are constructed in such a way that limits their output voltage to a maximum of 30 kV. The power grid with voltages up to 800 kV or more can not be directly supplied by those generators - a reason why large power plants nowadays are using power step-up transformers in order to transform their generated voltage to a higher voltage level suitable for the interface with the transmission grid.
During the last century, a number of attempts were made at developing a high-voltage generator that could be connected directly to the power grid, i.e. without going via the step-up transformer. However, generators are presently constructed for voltages up to 30 kV only. The step-up transformer imposes great drawbacks on the power plant as a whole, starting from reduction in efficiency, high maintenance costs, more space, less availability and not to forget the increased environmental impact of the plant.
ABB has developed in close co-operation with Vattenfall (the Swedish state-owned power utility) a new high-voltage generator with innovative features that enables it to be connected directly to the transmission grid; its output voltage can reach levels up to 400 kV. With the new technology, future transformer-less power plants can be constructed leading to a new concept of energy systems.
The new apparatus has been named Powerformer; its benefits such as higher efficiency, better availability, lower maintenance costs and reduced environmental impact are straightforward consequences of transformer-less power plants.
INNOVATIVE DESIGN
The Powerformer represents a completely new concept in generator technology. Powerformer has been designed with several unique features that allow it to exceed the 30kV limit, including a winding consisting of XLPE power cables and an innovative stator design.
Conventional generators produce electricity at voltages that are too low to be efficiently transmitted over long distances. Linking them to the high-voltage transmission network requires large transformers to boost the voltage. The Powerformer uses advanced cable technology to generate high-voltage directly, eliminating the need for a transformer and other associated equipment.
The Powerformer’s unique design has a number of operational and environmental benefits. Because the total installation is smaller and more efficient, it also reduces maintenance costs. It can be custom-built to provide any output voltage, and other aspects of its design contribute to greater network stability and more reliable performance during periods of short-term power overload.
Powerformer Windings: The magnetic circuit of Powerformer makes certain demands on the winding. The winding consists of a power cable with solid insulation and two semiconducting layers, one surrounds the conductor and the other outside the insulation, the semiconducting layers serves as an equipotential surface that forces the electric field to be uniform around the circumference.
The insulation material is cross-linked polyethylene (XLPE), a material successfully used in high-voltage power cables since the 1960s. The cables are threaded through the stator slots to form a winding that produces the desired high-voltage. The use of high-voltage cables in Powerformer windings offers major advantages over conventional designs. Firstly, in conventional generators maximizing the current loading in the machine favor the use of rectangular conductors in order to obtain maximum copper packing density for the stator windings. These conductor shapes are, however, characterized by an uneven field distribution having high field concentrations in the corners of the conductors.
THE FIRST POWERFORMER
The Powerformer can generate electricity at voltages between 30 kV and 400 kV. The first operational generator, with a rating of 45 kV, 11 MVA at 600 rpm, was successfully installed at a power plant in northern Sweden owned and operated by the Foundation Porjus Hydro Centre. The Center, which serves as a development and training facility for hydro power technology, is run by the Swedish energy company Vattenfall, Kvaerner Turbin and ABB.
HISTORY OF POWERFORMER
Today’s high-voltage generators are constructed in such a way that limits their output voltage to a maximum of 30 kV. The power grid with voltages up to 800 kV or more can not be directly supplied by those generators - a reason why large power plants nowadays are using power step-up transformers in order to transform their generated voltage to a higher voltage level suitable for the interface with the transmission grid.
During the last century, a number of attempts were made at developing a high-voltage generator that could be connected directly to the power grid, i.e. without going via the step-up transformer. However, generators are presently constructed for voltages up to 30 kV only. The step-up transformer imposes great drawbacks on the power plant as a whole, starting from reduction in efficiency, high maintenance costs, more space, less availability and not to forget the increased environmental impact of the plant.
ABB has developed in close co-operation with Vattenfall (the Swedish state-owned power utility) a new high-voltage generator with innovative features that enables it to be connected directly to the transmission grid; its output voltage can reach levels up to 400 kV. With the new technology, future transformer-less power plants can be constructed leading to a new concept of energy systems.
The new apparatus has been named Powerformer; its benefits such as higher efficiency, better availability, lower maintenance costs and reduced environmental impact are straightforward consequences of transformer-less power plants.
INNOVATIVE DESIGN
The Powerformer represents a completely new concept in generator technology. Powerformer has been designed with several unique features that allow it to exceed the 30kV limit, including a winding consisting of XLPE power cables and an innovative stator design.
Conventional generators produce electricity at voltages that are too low to be efficiently transmitted over long distances. Linking them to the high-voltage transmission network requires large transformers to boost the voltage. The Powerformer uses advanced cable technology to generate high-voltage directly, eliminating the need for a transformer and other associated equipment.
The Powerformer’s unique design has a number of operational and environmental benefits. Because the total installation is smaller and more efficient, it also reduces maintenance costs. It can be custom-built to provide any output voltage, and other aspects of its design contribute to greater network stability and more reliable performance during periods of short-term power overload.
Powerformer Windings: The magnetic circuit of Powerformer makes certain demands on the winding. The winding consists of a power cable with solid insulation and two semiconducting layers, one surrounds the conductor and the other outside the insulation, the semiconducting layers serves as an equipotential surface that forces the electric field to be uniform around the circumference.
The insulation material is cross-linked polyethylene (XLPE), a material successfully used in high-voltage power cables since the 1960s. The cables are threaded through the stator slots to form a winding that produces the desired high-voltage. The use of high-voltage cables in Powerformer windings offers major advantages over conventional designs. Firstly, in conventional generators maximizing the current loading in the machine favor the use of rectangular conductors in order to obtain maximum copper packing density for the stator windings. These conductor shapes are, however, characterized by an uneven field distribution having high field concentrations in the corners of the conductors.
THE FIRST POWERFORMER
"The new high-voltage generator represents a major innovation," said Göran Lindahl, ABB’s President and CEO. "It radically changes a 100-year old technology and establishes a new class of rotating machines. With its unique design the generator provides our customers with substantial benefits, such as better system performance, higher efficiency, lower maintenance costs and reduced environmental impact."
The Powerformer was developed by ABB Corporate Research and ABB Power Generation in cooperation with Vattenfall. ABB employs approximately 1,200 scientists and technicians in 8 corporate research centers in Europe and America. A further 17,000 engineers spread across ABB’s global business areas are also engaged in research and development. The ABB Group employs approximately 216,000 people.
