Pnc&viet
Power requirement is increasing day by
day due to the maximum power utilization. In
order to meet this demand a large power has
to be generated in an efficient way. A new
machine namely “Powerformer” can do this.
The conventional plant generated voltage is
limited to 30KV. This voltage is stepped up to
a high voltage level in the order of 800KV with
the help of power step-up transformers. The
step-up transformer imposes great drawbacks
on the power plant, starting from reduction in
efficiency, high maintenance costs, and more
space less availability.
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During the last century, a number of
attempts were made at developing a highvoltage generator that could be connected
directly to the power grid, i.e. without going
any step-up transformer. The powerformer
has opened a new chapter in the generation
and transmission of electrical energy.
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Powerformer Concept
Innovative Design
The first Powerformer Installation
Advantages of Powerformer
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Powerformer is a new machine, It is a 3-phase AC
generator with a rotor of conventional design.
The difference compared with conventional generator
lies in the stator windings.
In Powerformer stator winding consists of highvoltage cables instead of today’s windings with a
square cross-section.
By using high-voltage cables as generator stator
winding, it is possible to highly increase the
generated voltage.
The decisive difference between this design and
present-day technology is that Powerformer allows
direct connection to the high-voltage grid.
1. Generator
2. Generator circuit breaker
3. Surge arrester
4. step-up transformer
5. Line circuit breaker
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This design implies the omission of the
generator circuit breaker, the high current
bus bar and the step-up power transformer
from the power plant, because Powerformer
comprises the functions of both generator
and step-up transformer as realized from
above Figure
As a consequence there is an increase up to
1.5% in total electric power efficiency
compared with today’s best designs,
without using superconductive materials.
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Powerformer has been designed with
several unique features that allow it to
exceed the 30kV limit, including a winding
consisting of power cables and an
innovative stator design.
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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 insulation material is cross-linked
polyethylene
High-voltage power cables are used in
winding.
These cables used to many advantages over
conventional designs
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The stator of Powerformer consists of a
laminated core.
These laminated core are built up from
electrical sheet.
The winding is located in the slots formed
by the teeth, the cross section of the slots
decreases . The winding turn requires less
cable insulation the closer it is to the rotor.
Each slot has circular bores at intervals,
forming narrow waists between the winding
layers, as shown in Figure below.
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The world’s first high-voltage generator
based on the new technology; a hydropower
machine is rated at 11 MVA, 45 kV, and 600
rpm. The machine has already been tested
in the factory and installed at the Porjus
Hydropower Center on the Lule River in
northern Sweden. The machine is directly
connected to the 45 kV transmission power
grids; its stator is shown in below Figure
1.It generates Low voltage
(<30kv)
1.It generates High voltage
(>>30kV)
2. High current
2. Low current
3. Stator has Short teeth
3. Stator Long teeth
4. High weight
4. Less weight
5. Mount winding is used
5. Thread cable is used
6. Impregnating windings
6. Extrusion type winding is used
7. High temperature
7. Low temperature
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higher efficiency
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low maintenance costs
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power transfer form generator to power
grid without going via the step-up
transformer
better availability
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ABB’s new high-voltage generator
(Powerformer) has been studied the new concept
provides the possibility to directly connect a
rotating machine to the high-voltage power grid
without going any step-up transformer.
Powerformer is a high-voltage generator; the
limitation in its rated voltage is set solely by the AC
Power cable and the cable accessories
(terminations and joints) used in its stator winding.
This means that Powerformer of voltage ratings up
to 400 kV can be realized, although has not been
proved yet.