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Synchronous condenser solutions
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Bringing grids in line
with new requirements
Global climate change poses new challenges for power
generation and transmission. Innovative solutions
will contribute to the reduction in CO2 emissions and
an optimized use of energy resources. The most crucial
points in today’s and tomorrow’s power supply are
sustainability, security, and efficiency.
Synchronous condenser solutions are being introduced
worldwide to support today’s transmission system requirements. The addition of renewables-based power genera-
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tion to the energy mix, phaseout of conventional power
plants, new HVDC systems, and the extension of power
supply systems to remote areas influence the stability of
transmission networks.
Siemens offers tailor-made turnkey synchronous
condensers to address the customers’ needs based on
proven, reliable in-house equipment, extensive know-how
on transmission system requirements, and project
execution experience.
Benefits
Applications
• Short-circuit power capability
Synchronous condensers support and improve power
transmission quality in a wide range of applications:
• Reactive power compensation
• Short-term overload capability
• Inertia to the transmission system
• Leveling out of »grid signals«
• Support of grid to island operation capabilities
• Stabilization of grids
•High-voltage DC transmission links based on
line-commutated converter technology
•Transmission grids with a high amount of power infeed
from renewable sources
• Retirement/shutdown of conventional power plants
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Technology and
system overview
Siemens synchronous condenser solutions comprise a horizontal synchronous generator connected to the high-voltage transmission network via a step-up transformer.
Siemens supplies a broad range of generators up to
2,235 MVA. The generators are air-, hydrogen-, and
water-cooled.
The synchronous generator is started up and stopped
by a frequency-controlled electric motor (pony motor)
or a starting frequency converter.
When the generator has reached an operating speed that
is synchronous to the system frequency, it is synchronized
with the transmission network and acts as a motor providing reactive and short-circuit power to the transmission
network.
Synchronous electrical machines like synchronous
generators can generally be used as synchronous condensers. Without active power delivery or con­sumption,
the machines can act in the same way as a capacitor or
a reactor, depending on the excitation field current.
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1 Synchronous generator
2 Generator step-up transformer
3 Static/brushless excitation
4 Pony motor/starting frequency converter
5 Isolated phase bus duct
6 Control and protection system
7 Auxiliary transformer
8 Generator circuit breaker
9 Optional external coolers
10 Complete civil and construction works
Siemens in-house equipment
System overview – synchronous condenser solution
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Proven, reliable
in-house products
Generators
A generator is an electric machine that converts mechani­
cal energy into electric power. It operates on the basis of
the dynamoelectric principle that Werner von Siemens
registered for a patent with the first dynamo generator in
1867. The principle states that an electric generator does
not need to have an electric current supplied from the outside to start generating electric power. A self-reinforcing
electrical induction can take place due to the residual
magnetism of iron.
Today, the mechanical excitation, the generator’s need
to generate electricity, is often provided by a turbine. It
drives a shaft that is known as the rotor. This shaft rotates in
the stator core, in other words, inside the generator. The
rotor is equipped with an electromagnet, and the moving
magnetic field of the rotor causes a charge transfer in the
conductor coils of the stator. The charge transfer generates
electric voltage between the ends of the conductors.
This is how the mechanical energy, which acts on the
rotor, produces electric energy – power – in the stator.
Excitation systems
The generator is equipped with either a brushless exciter
or a conventional static exciter with brushes. The two
solutions have different characteristics in terms of dynamic
behavior, and are selected according to the project requirements.
Contrary to power electronics-based static VAr
compen­sators (SVCs), a synchronous condenser features
the major advantages of injecting large amounts of
short-circuit power and providing inertia due to its rotating
mass. The same generators are implemented for
synchronous condenser applications.
Starting frequency
converter/pony motor
The startup and breaking system of a Siemens synchronous condenser is either based on a frequency-controlled
pony motor or a starting frequency converter. These two
methods have different advantages and will be offered
from Siemens’ own portfolio depending on the customer’s
requirements.
Control and protection system
Generator performance is dynamically controlled by an
automatic voltage regulator (AVR), which is an integral
part of all excitation systems. In a brushless excitation system, the AVR is separately installed, and in case of static
excitation system, AVR software is integrated in the
control system of the static excitation system. In addition
to the AVR system, a generator control panel is required
for start and stop sequences, protection of the generator
(vibration and temperature) and for cooling system
control.
Nuc
Segment cooling
H 2O
1000–2235 MVA (4-pole)
50 Hz 550–1300 MVA
H2
Fossil
60 Hz 800–1065 MVA
50 Hz 350–570 MVA
60 Hz 310–540 MVA
Manufacturing of an air-cooled generator
Air
Industrial
50 Hz 165–370 MVA
60 Hz 165–310 MVA
50/60 Hz 25–300 MVA
25–65 MVA (4-pole)
The Siemens generator portfolio
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Project references
Black Sea 3x60 MVAr, Republic of Georgia
Siemens installed three 60 MVAr synchronous condensers
at the Georgia Black Sea HVDC station in June 2012. This
synchronous condenser solution supports the transmission network between Georgia and Turkey with the
required short-circuit power in order to operate the newly
installed HVDC back-to-back station.
Bjæverskov 1x250 MVAr, Denmark
In Denmark, Siemens delivered a 250 MVAr synchronous
condenser solution that started operation in 2013, providing the transmission system with a short-circuit power of
more than 800 MVA in addition to reactive power control.
The installation of this stand-alone synchronous condenser solution will enable the transmission system operator Energinet.dk to operate the transmission network
without the need for a large thermal power plant. This
makes the installation an economically and environmentally advantageous investment enabling the infeed of
large amounts of renewable energy into the transmission
network.
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Fraugde and Herslev 2x200 MVAr, Denmark
These solutions will ensure the transmission system
stability in the country’s regions of Funen and Zealand.
Siemens’ scope of supply comprises engineering, procurement, and construction of these facilities. The customer
Energinet.dk will manage the civil work. Each synchronous condenser solution is capable of delivering more
than 900 MVA of short-circuit power and +150 / -75 MVAr
of reactive power. The projects are running in trial
operation as of August 2014.
Feda 1x200 MVAr, Norway
This solution will secure short circuit power for the
NorNed HVDC connection, especially during the planned
upgrade of the overhead line in the southern region of
Norway. Siemens’ scope of supply comprises engineering,
procurement, and construction of these facilities including
necessary civil works. The synchronous condenser solution for Feda is capable of delivering more than 750 MVA
of short-circuit power and +170 / -90 MVAr of
reactive power. The project is scheduled for trial
operation at the end of 2014.
Talega 2x225 MVAr, USA
The turnkey supply of two 225 MVA synchronous condenser systems for Talega substation in California will support the California grid with reactive power, shortcircuit power, and inertia. Siemens’ scope of supply
comprises the complete engineering, procurement, and
construction of these facilities including necessary civil
works. Each synchronous condenser solution for Talega is
capable of delivering +225 / -120 MVAr of reactive power.
The units are planned to commence commercial operation
in July 2015.
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Published by and copyright © 2014:
Siemens AG
Energy Sector
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Siemens AG
Energy Management Division
Freyerslebenstrasse 1
91058 Erlangen, Germany
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The information in this document contains
general descriptions of the technical options
available, which may not apply in all cases.
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be specified in the contract.