Title of Invention

ELECTRICAL ISLAND NETWORK AND METHOD FOR OPERATION CONTROL OF ELECTRICAL ISLAND NETWORK

Abstract The present invention relates to an island network with at least one power generator, which uses renewable energy sources, wherein the power generator is preferably a wind-power station with a first synchronous generator, with a dc voltage intermediate circuit with at least a first rectifier and an inverter, with a second synchronous generator and an internal combustion engine that can be coupled to the second synchronous generator. To realize an island network, for which the internal combustion engine can be deactivated completely, as long as the wind-power station generates sufficient power for all connected loads at the highest possible efiiciency, a completely controllable wind-power station (10) and an electromagnetic coupling (34) between the second synchronous generator (32) and the internal combustion engine (30) are provided.
Full Text ELECTRICAL ISLAND NETWORK AND METHOD FOR OPERATION CONTROL
OF ELECTRICAL ISLAND NETWORK
The present invention relates to an electrical island network with at least one power
generator, which is coupled to a first generator. A second generator is further provided, which
can be coupled to an internal combustion engine. In such island networks, the power generator,
which is connected to the first generator, is frequently a renewable-energy power generator, e.g.,
a wind-power station, hydroelectric power plant, etc.
Such island networks are generally known and are used especially for supplying power to
areas, which are not connected to a central power-supply network but in which renewable energy
sources, such as wind and/or sun and/or water power, and the like, are available. These areas can
be islands, for example, or remote or hard-to-reach areas with peculiarities in terms of size,
location, and/or weather patterns. However, power, water, and heat also must be supplied to such
areas. The energy required for these systems, at least the electrical energy, is provided and
distributed by the island network. However, for fault-free operation, modern electrical devices
require the maintenance of relatively strict limit values for voltage and/or frequency fluctuations
in the island network.
To be able to maintain these limiting values, among other things, so-called wind-diesel
systems are used, for which a wind-power station is used as the primary energy source. The
alternating current generated by the wind-power station is rectified and then converted by an:
inverter into alternating current with the required network power frequency. This method
generates a network power frequency that is independent of the rpm of the wind-power station
generator, and thus of its frequency.
Therefore, the network power frequency is determined by the inverter. Here, two different
variants are available. The first variant is a so-called self-commutated inverter, which can
generate a stable network power frequency itself. However, such self-commutated inverters
require high technical expense and are correspondingly expensive. One alternative variant to a
self-commutated inverter is a network-commutated inverter, which synchronizes the frequency of
its output voltage with an existing network. Such inverters are considerably more economical
than self-commutated inverters, but always require a network, with which they can be
synchronized. Therefore, for a network-commutated inverter, a network generator must always
be available, which provides the control parameters necessary for network control of the inverter.
Such a network generator is a synchronous generator, for example, which is driven by an internal
combustion engine (diesel motor), in known island networks.
This means that the internal combustion engine must run continuously to drive the
synchronous generator as the network generator. This is also disadvantageous in view of
maintenance requirements, fuel consumption, and the loading of the environment with exhaust

gases, because even if the internal combustion engine must provide only a fraction of its available
power for driving the generator as the network generator, the power frequently equals only 3-5 kW, and
the fuel consumption is not insignificant but equals several liters of fuel per hour.
Another problem for known island networks is that so-called "dump loads" must be provided,
which consume the excess electrical energy generated by the primary power generator, so that the
primary power generator is not set into a free-running operation when loads are turned off, which in
turn could lead to mechanical damage to the primary power, generator due to an rpm that is too high.
This is especially problematic for wind-power stations as the primary power generators.
The invention is based on the task of preventing the previously mentioned disadvantages and
improving the efficiency of an island network.
In order to achieve the task, the present invention provides an electrical island network with at
least one first power generator, which uses a renewable energy source, wherein the power generator is
preferably a wind-power station with a generator, wherein a second generator is provided, which can be
coupled to an internal combustion engine, wherein the wind-power station can be controlled in terms of
its rpm and blade position, characterized in that a bus bar for feeding the generated energy into the
network is formed and a device connected to a bus bar for detecting the power required in the network
is provided, and at least one intermediate storage device such as herein described for storing electrical
energy is provided, wherein the intermediate storage device, can be coupled to the first power generator
and for the case that the output power of the first power generator is greater than the power of the loads
required in the network, at first electrical energy of the first generator is supplied to the intermediate
storage device if the intermediate storage device is not full, and/or if more energy is consumed in the
network than is generated by the first power generator, at first the electrical intermediate storage device
is used for delivering power.
The present invention also provides an electrical island network with at least one first primary
power generator for generating electrical energy for an electrical island network, wherein a synchronous
generator is provided, which has the function of a network generator, wherein the synchronous
generator can here work in motor mode and the energy required for the motor operation is made
available by the primary power generator.
The present invention further provides a method for operation control of an electrical island
network with at least one wind-power station, wherein the wind-power station is controlled such that it
always generates only the required electrical power as long as the consumption of the electrical power
in the network is less than the electrical energy generation capacity of the wind-power station.
Advantageous refinements are described in the subordinate claims.

The invention is based on the knowledge that the second generator, which has the function of
the network generator, can also be driven with the electrical energy of the primary power generator
(wind-power station), so that the internal combustion engine can be completely turned off and
decoupled from the second generator. Here, the second generator is no longer in generator operation,
but instead in motor operation, wherein the electrical energy required for this function is delivered by
the primary power generator or its generator. If the coupling between the second generator and the
internal combustion engine is an electromagnetic coupling, then this coupling can be activated by
supplying electrical power from the primary power generator or its generator. If the electrical power is
turned off at the coupling, the coupling is separated. The second generator is then powered and driven
(motor operation) with electrical energy from the primary power generator as previously described, for
the deactivated operation of the internal combustion engine, so that despite the deactivated internal
combustion engine, the network generator remains in operation. As soon as activation of the internal
combustion engine and thus the generator operation of the second generator is required, the internal
combustion engine can be started and coupled by means of the electrically activated coupling with the
second generator so that this second generator can provide additional energy for the electrical island
network in the generator operation.
The use of a completely controllable wind-power station permits the elimination of "dump
loads," because the wind-power station is able to generate the required power through its complete
controllability, thus variable rpm and variable blade position, so that "disposal" of

excess energy is not required since the wind-power station generates the exact amount of
required power. Therefore, so that the wind-power station generates only as much energy as
needed in the network (or is required for recharging intermediate storage devices), no excess
power must be consumed uselessly and the total efficiency of the wind-power station but also of
the entire island network becomes considerably better than for the use of "dump loads."
In one preferred embodiment of the invention, the wind-power station contains a
synchronous generator, which is connected after an inverter. This inverter consists of a rectifier,
a dc voltage intermediate circuit, and a frequency converter. If another energy source providing
another dc voltage (dc current), e.g., a photovoltaic element, is embodied in the island network,
then it is advantageous that such other primary power generators, such as photovoltaic elements,
are connected to the dc voltage intermediate circuit of the inverter, so that the energy of the
additional renewable energy source can be fed into the dc voltage intermediate circuit. This
configuration can increase the power made available by the first primary power generator.
On one hand, to equalize fluctuations of the available power and/or an increased power
demand spontaneously and, on the other hand, to be able to use available energy, which is not in
demand at the moment, preferably intermediate storage devices are provided, which store
electrical energy and which can be discharged quickly on demand. Such storage devices can be
e.g., electrochemical storage devices like accumulators, but also capacitors (caps) or also
chemical storage devices like hydrogen storage devices, which store hydrogen generated by
electrolysis with the excess electrical energy. To discharge their electrical energy, such storage
devices are also connected directly or via corresponding charging/discharging circuits to the dc
voltage intermediate circuit of the inverter.
Another form of energy storage is the conversion into rotational energy, which is stored
in a flywheel. This flywheel is coupled to the second synchronous generator in a preferred
refinement of the invention and thus also permits the stored energy to be used for driving the
network generator.
All storage devices can be supplied with electrical energy when the energy consumption
in the island network is less than the power capacity of the primary power generator, e.g., the
wind-power station. For example, if the primary power generator is a wind-power station with
1.5 MW nominal power or a wind array with several wind-power stations with 10 MW nominal
power and the wind patterns are such that the primary power generator can be operated in normal
mode, although the power consumption in the island network is clearly less than the nominal
power of the primary power generator, in such a mode (especially at night and in times of low
consumption in the island network), the primary power generator is controlled such that all
energy storage devices are charged (filled). In this way, the energy storage devices can be

activated, under some circumstances only temporarily, in times when the power consumption of
the island network is greater than the power made available by the primary power generator.
In one preferred refinement of the invention, all power generators and intermediate
storage devices with the exception of the energy components connected to the second generator
(internal combustion engine, flywheel) are connected to a common dc voltage intermediate
circuit, which is configured like a bus and which is terminated with an individual,
network-commutated converter (inverter). The use of an individual, network-commutated
inverter on a dc voltage intermediate circuit produces a very economical arrangement.
It is further advantageous when other (redundant) internal combustion engines and third
generators (e.g., synchronous generators) that can be coupled to these engines are provided to
generate power by operating the other (redundant) generator systems when there is a greater
power demand than is available from the renewable-energy power generators and the stored
power.
In general, the power frequency in the network can be used to determine whether the
available power corresponds to the required power. For an excess supply of power, the network
power frequency increases, while it falls for too little power. However, such frequency deviations
appear delayed and equalizing such frequency deviations becomes more and more difficult with
increasing complexity of the network.
To enable fast adaptation to the power, a device, which can detect the power required in
the network, is connected to the bus bar. In this way, a demand for power or an excess supply of
power can be recognized and compensated immediately before fluctuations in the network power
frequency can appear at all.
In the following, an embodiment of the invention is explained in more detail as an
example with reference to the accompanying drawings. Shown here are:
Figure 1, a block circuit diagram of an island network according to the invention;
Figure 2, a variant of the principle shown in Figure 1; and
Figure 3, a preferred embodiment of an island network according to the invention.
Figure 1 shows a wind-power station with a downstream converter consisting of a
rectifier 20, by means of which the wind-power station is connected to a dc voltage intermediate
circuit 28, as well as an inverter 24 connected to the output of the dc voltage intermediate circuit
28.
In parallel to the output of the inverter 24, a second synchronous generator 32 is
connected, which is connected in turn via an electromagnetic coupling 34 to an internal
combustion engine 30. The output lines of the inverter 24 and the second synchronous generator
32 provide the (not shown) load with the required energy.

In this way, the wind-power station 10 generates the power to be supplied to the load.
The energy generated by the wind-power station 10 is rectified by the rectifier 20 and fed into
the dc voltage intermediate circuit 28.
The inverter 24 generates an alternating voltage from the applied dc voltage and feeds it
into the island network. Because the inverter 24 is embodied for reasons of cost preferably as a
network-commutated inverter, a network generator is present, with which the inverter 24 can be
synchronized.
This network generator is the second synchronous generator 32. This synchronous
generator 32 works for a deactivated internal combustion engine 30 in the motor operation and
here acts as a network generator. In this operation mode, the drive energy is electrical energy
from the wind-power station 10. This drive energy for the synchronous generator 32 must also be
generated by the wind-power station 10 just like the losses of the rectifier 20 and the inverter 24.
In addition to the function of the network generator, the second synchronous generator 32
performs other tasks, like the reactive power generation in the network, the supply of
short-circuit current, acting as a flicker filter, and voltage regulation.
If loads are turned off and thus the energy demand falls, then the wind-power station 10
is controlled so that it generates less energy correspondingly, so that the use of dump loads can
be eliminated.
If the energy demand of the loads increases so much that this can no longer be covered
only by the wind-power station, the internal combustion engine 28 can be started and a voltage is
applied to the electromagnetic coupling 34. In this way, the coupling 34 creates a mechanical
connection between the internal combustion engine 30 and the second synchronous generator 32
and the generator 32 (and network generator) supplies the required energy (now in generator
operation).
Through suitable dimensioning of the wind-power station 10, it can be achieved that on
average sufficient energy for powering the loads is provided from wind power. Therefore, the
use of the internal combustion engine 30 and the resulting fuel consumption is reduced to a
minimum.
In Figure 2, a variant of the island network shown in Figure 1 is shown. The setup
essentially corresponds to the solution shown in Figure 1. The difference here is that no internal
combustion engine 30 is assigned to the second generator 32, which acts as the network
generator. The internal combustion engine 30 is connected to another third (synchronous)
generator 36, which can be activated on demand. The second synchronous generator 32 thus
operates constantly in motor operation as the network generator, reactive-power generator,
short-circuit current source, flicker filter, and voltage regulator.

In Figure 3, another preferred embodiment of an island network is shown. This figure
shows three wind-power stations 10, which form, e.g., a wind array, with first (synchronous)
generators, which are each connected to a rectifier 20. The rectifiers 20 are connected in parallel
to the output side and feed the energy generated by the wind-power station 10 into a dc voltage
intermediate circuit 28.
Furthermore, three photovoltaic elements 12 are shown, which are each connected to a
boost converter 22. The output sides of the boost converters 22 are connected in parallel to the dc
voltage intermediate circuit 28.
Furthermore, an accumulator block 14 is shown, which stands symbolically for an
intermediate storage device. In addition to an electrochemical storage device like the
accumulator 14, this intermediate storage device can be a chemical as well as a hydrogen storage
device (not shown). The hydrogen storage device can be coated with hydrogen, for example,
which is obtained by electrolysis.
Next to this, a capacitor block 18 is shown, which exhibits the ability of using suitable
capacitors as intermediate storage devices. These capacitors can be so-called Ultra-caps from
Siemens, for example, which are distinguished by low losses in addition to high storage capacity.
Accumulator block 14 and capacitor block 18 (both blocks can also have several
instances) are each connected via charging/discharging circuits 26 to the dc voltage intermediate
circuit 28. The dc voltage intermediate circuit 28 is terminated with a (single) inverter 24 (or a
plurality of inverters connected in parallel), wherein the inverter 24 is preferably embodied in a
network-commutated way.
On the output side of the inverter 24, a distributor 40 (optionally with a transformer) is
connected, which is powered by the inverter 24 with the network voltage. On the output side of
the inverter 24, a second synchronous generator 32 is also connected. This synchronous
generator 32 is the network generator, reactive power and short-circuit current generator, flicker
filter, and voltage regulator of the island network.
A flywheel 16 is coupled to the second synchronous generator 32. This flywheel 16 is
also an intermediate storage device and can store energy, e.g., during the motor-driven operation
of the network generator.
In addition, an internal combustion engine 30 and an electromagnetic coupling 34, which
drive the generator 32 and which operate as a generator when there is too little power from
renewable energy sources, can be assigned to the second synchronous generator 32. In this way,
the missing energy can be fed into the island network.
The internal combustion engine 30 assigned to the second synchronous generator 32 and
the electromagnetic coupling 34 are indicated by dashed lines to make clear that the second
synchronous generator 32 can be operated alternatively only in motor mode (and optionally with

a flywheel as an intermediate storage device) as the network generator, reactive-power generator,
short-circuit current source, flicker filter, and voltage regulator.
Especially when the second synchronous generator 32 is provided without internal
combustion engine 30, a third synchronous generator 36 with an internal combustion engine can
be provided to equalize a longer lasting power gap. This third synchronous generator 36 can be
separated from the island network by a switching device 44 in rest mode in order not to load the
island network as an additional energy load.
Finally, a (up/computer) controller 42 is provided, which controls the individual
components of the island network and thus allows an essentially automatic operation of the
island network.
Through suitable design of the individual components of the island network, the
wind-power station 10 can provide on average sufficient energy for the loads. This supply of
energy is optionally supplemented by the photovoltaic elements.
If the power supplied by the wind-power station 10 and/or the photovoltaic elements 12 is
less/greater than the demand from the loads, the intermediate storage devices 14, 16, 18 can be
applied (discharged/charged) to either supply (discharge) the missing power or to store (charge)
the excess energy. The intermediate storage devices 14, 16, 18 thus smooth the constantly
fluctuating supply from the renewable energies.
Here, it is essentially dependent on the storage capacity of the intermediate storage
devices 14, 16, 18, over what time period what power fluctuation can be equalized. With
over-dimensioning of the intermediate storage devices, a few hours up to a few days can be set as
the time period.
The internal combustion engines 30 and the second or third synchronous generators 32,
36 must be turned on only if there are power gaps that exceed the capacity of the intermediate
storage devices 14, 16, 18.
In the preceding description of the embodiments, the primary power generator is always
one that uses a renewable energy source, such as wind or sun (light). However, the primary
power generator can also operate with another renewable energy source, e.g., water power, or it
can also be a generator, which consumes fossil fuels.
A seawater desalination plant (not shown) can also be connected to the island network, so
that in times, in which the loads on the island network require significantly less electrical power
than the primary power generator can provide, the seawater desalination plant consumes the
"excess," i.e., still available, electrical power to generate service water/drinking water, which can
then be stored in reservoirs. If at certain times the electrical energy consumption of the island
network is so large that all energy generators are barely able to provide this power, the seawater

desalination plant operation is brought down to a minimum, optionally even completely
deactivated. Also, the seawater desalination plant can be controlled by the controller 42.
During those times that the electrical power of the primary power generator is only
partially required by the electrical network, a pump storage device, which is also not shown, can
also be operated, by means of which water (or other liquid media) is brought from a low
potential to a high potential, so that when needed, the electrical power of the pump storage
device can be accessed. The pump storage device can also be controlled by the controller 42.
It is also possible that the seawater desalination plant and a pump storage device are
combined, in that the service water (drinking water) generated by the seawater desalination plant
is pumped to a higher level, which can then be used to drive the generators of the pump storage
device if needed.
As an alternative to the variants of the invention described and shown in Figure 3, other
variations to the solution according to the invention can also be performed. For example, the
electrical power of the generators 32 and 36 (see Figure 3) can be fed rectified via a rectifier to
the bus bar 28.
Then, if the power supplied by the primary power generator 10 or the intermediate
storage devices 12, 14, 16, 18 is too low or is applied as much as possible, the internal
combustion engine 30 is started and this then drives the generator 32, 36. The internal
combustion engine then provides the electrical energy within the island network as much as
possible for the island network, but simultaneously it can also charge the intermediate storage
device 16, thus the flywheel in turn, and for feeding the electrical energy, the generators 32 and
36 in the dc current intermediate circuit 28 can also charge the intermediate storage devices 14,
18 shown there. Such a solution has the advantage, in particular, that the internal combustion
engine can run in an advantageous, namely, optimal operation, where the exhaust gases are also
• kept as low as possible and also the rpm is in an optimum range, so that the consumption of the
internal combustion engine is in the best possible range. For such an operation, when, e.g., the
intermediate storage devices 14, 18, or 16 are filled as much as possible, the internal combustion
engine can then be deactivated, and then the network power supply is realized as much as
possible with the energy stored in the storage devices 14, 16, 18, if insufficient energy can be
provided from the energy generators 10, 12. If the charge state of the intermediate storage
devices 14, 16, 18 falls below a critical value, then in turn the internal combustion engine is
turned on, and energy provided by the internal combustion engine 30 is supplied to the
generators 32 and 36 in the dc current intermediate circuit 28 and the intermediate storage
devices 14, 16, 18 are also charged in turn.
In the previously described variants, care is taken especially that the internal combustion
engine can run in an optimum rpm range, which improves its overall operation.

Here, conventional rectifiers (e.g., rectifier 20) are connected downstream in the
generators 32, 36, by means of which the electrical energy is fed into the dc current intermediate
circuit 28.
A form of the applied intermediate storage device 14 is an accumulator block, e.g., a
battery. Another form of the intermediate storage device is a capacitor block 18, e.g., an Ultracap
model capacitor from Siemens. The charging behavior, but primarily the discharging behavior of
the previously mentioned intermediate storage device is relatively different and should be
addressed in the present invention.
Thus, accumulators, like other conventional batteries, exhibit a loss in capacity, even if
small, but irreversible, for each charge/discharge cycle. For very frequent charge/discharge
cycles, in a comparatively short time this leads to a significant loss in capacity, which makes a
replacement of this intermediate storage device necessary in a correspondingly fast time
depending on the application.
Dynamically loadable intermediate storage devices like an Ultracap model capacitor
storage device or also a flywheel storage device do not have the previously mentioned problem.
However, Ultracap model capacitor storage devices and also flywheel storage devices are
considerably more expensive than a conventional accumulator block or other battery storage
devices in terms of a single kilowatt-hour.
Unlike the application of renewable raw materials or solar energy, wind energy can rarely
be reliably predicted. Thus, attempts are made to generate as much energy as possible with
renewable sources and, if this energy cannot be consumed, to store it in storage devices with the
largest possible storage capacities in order to have this energy available and to be able to
discharge it when needed. Naturally, all energy storage devices are designed with maximum size
to be able to bridge the longest possible times without power.
Another difference between intermediate storage devices of the accumulator block type
and Ultracap model intermediate storage devices or flywheel storage devices is that the electrical
power of Ultracaps and flywheel storage devices can be discharged within a very short time
without harm, while intermediate storage devices of the accumulator block type do not have such
a high discharge rate (DE/DT).
Therefore, one aspect of the invention of the present application is also that the different
intermediate storage devices of different types can be used as a function of their operating
properties and costs for various tasks. In light of the preceding observations, it thus also does not
appear to be sensible to use an intermediate storage device of a flywheel storage device type or
an Ultracap with maximum capacity in order to bridge the longest possible times without power,
but these storage devices do have their strengths, especially in being able to bridge short times

without power without harm to the intermediate storage devices, while they are very expensive
for bridging very long times without power.
It is also not meaningful to use intermediate storage devices of an accumulator block type
or a battery storage device for frequency regulation, because the constant charge/discharge
cycles lead very quickly, namely within a few weeks and at best months, to irreversible losses in
capacity and force the already mentioned exchange of such a storage device. However,
intermediate storage devices of an accumulator block type or other battery storage devices could
be used to form a "long-term storage device," which takes over the supply of power during losses
on the order of minutes (e.g., from a range of 5-15 minutes), while dynamically loadable
Ultracap model intermediate storage devices and/or a flywheel storage device are used for
frequency regulation, i.e., for reducing the frequency in the network supplying additional energy
and for increasing frequency in the network storing energy.
Consequently, different ways of using the intermediate storage devices of various types
for still justifiable costs in the network, especially for an island network, can contribute to
frequency stability of the network, but can also reliably bridge losses in power in the generation
of electrical energy on the generator side for a few minutes. Consequently, through the different
use of intermediate storage devices of different types, the network is protected, on one hand, in
terms of frequency stability, on the other, in terms of the sufficient power supply for a time in the
range of minutes, when the available energy on the generator side is not sufficient.
Because the individual components of the generator side are controlled by the controller
device 42, and the controller device also recognizes what type of network-supporting measures
must be performed, through a corresponding control of the intermediate storage devices, various
types can be used; first, an intermediate storage device for stabilizing the network power
frequency, and second, another intermediate storage device for bridging times without power on
the generator side in the range of minutes. Simultaneously, through the different use of
intermediate storage devices of various types, for different network problems, the costs for the
entire intermediate storage device can still be reduced to a relative minimum.
Therefore, in the reduction to practice, it is advantageous that the intermediate storage
device of an accumulator block type or a battery storage device provide a considerably larger
energy charging capacity than Ultracap intermediate storage devices or flywheel storage devices.
Thus, e.g., the capacity in the intermediate storage device of an accumulator type or a battery
storage device can be significantly more than five to ten times as large as the capacity of an
intermediate storage device of an Ultracap or a flywheel storage device type.

We Claim :
1. An electrical island network comprising:
at least one first power generator, which uses a renewable energy source, wherein
the power generator is a wind power station with a generator, wherein the wind power
station (10) can be controlled in terms of its rpm and blade position;
at least one second power generator having a function of a network generator;
an internal combustion engine, which can be coupled to the second power
generator if the combustion engine is turned on and decoupled from the second power
generator if the combustion engine is turned off;
a bus bar for feeding the generated energy into the island network;
a device connected to the bus bar for detecting the power required in the island
network;
at least one intermediate storage device for storing electrical energy, wherein the
intermediate storage device can be coupled to the first power generator, and wherein the
intermediate storage device comprises a first intermediate storage device for stabilizing the
network power frequency and a second intermediate storage device for bridging times
without power on the generator side in the range of the order of minutes; and
a controller for controlling the components of the island network, wherein the
controller is configured to control the island network such that, for the case that the output
power of the first power generator is greater than the power of the load required in the
network, at first electrical energy of the first generator is supplied to the intermediate
storage device, if the intermediate storage device is not full, and in the event of
more energy being consumed in the network than is generated by the first power
generator, at first the intermediate storage device is used for delivering power.
2. The electrical island network as claimed in claim 1, wherein the first power
generator is a synchronous generator, which contains a converter (22) with a dc voltage
intermediate circuit (28) with at least one first rectifier (20) and an inverter (24).
3. The electrical island network as claimed in claim 2, wherein there is provided at
least one electrical element (12, 14, 16, 18) being connected to the dc voltage intermediate

circuit for feeding electrical energy with dc voltage.
4. The electrical island network as claimed in claim 3, wherein the electrical
element is a photovoltaic element and/or a mechanical energy storage device and/or an
electrochemical storage device and/or a capacitor and/or a chemical storage device as the
intermediate storage device.
5. The electrical island network as claimed in one of the preceding claims, wherein
there is provided a flywheel as the second intermediate storage device, which can be
coupled to the second or a third power generator.
6. The electrical island network as claimed in one of the preceding claims, wherein
there are provided several internal combustion engines, which can each be coupled to a
generator.
7. The electrical island network as claimed in one of the preceding claims, wherein
there is provided a boost/buck converter (22) which is connected between the intermediate
storage device (12) and the dc voltage intermediate circuit (28).
8. The electrical island network as claimed in one of the preceding claims, wherein
there are provided charging/discharging circuits (26) which are connected between the
intermediate storage device (14, 18) and the dc voltage intermediate circuit (28).
9. The electrical island network as claimed in one of the preceding claims, having a
flywheel with a generator and a downstream rectifier (20) for supplying electrical energy
into the dc voltage intermediate circuit (28).
10. The electrical island network as claimed in one of the preceding claims, wherein
the at least one first power generator (10, 12) and the at least one intermediate storage
device (14, 16, 18) power a common dc voltage intermediate circuit.

11. The electrical island network as claimed in one of the preceding claims, having a
network-commutated inverter.
12. The electrical island network as claimed in one of the preceding claims, wherein
there is connected an electromagnetic coupling (34) between the second power generator
(32) and the internal combustion engine (30), and the energy for operating the
electromagnetic coupling is made available by an electrical storage device and/or by the at
least one first power generator.
13. The electrical island network as claimed in one of the preceding claims, wherein
a seawater desalination/service water generation plant is connected to the island network,
wherein this plant generates service water when the power supplied by the first power
generator is greater than the power consumption of the other electrical loads connected to
the island network.
14. The electrical island network as claimed in one of the preceding claims, wherein
a pump storage device is provided, which receives its electrical energy from the first power
generator.
15. The electrical island network as claimed in one of the preceding claims, wherein
the second generator is a synchronous generator, which has the function of a network
generator, wherein the synchronous generator can work in motor mode and the energy
required for the motor operation is made available by the first power generator.
16. The electrical island network as claimed in claim 15, wherein the second power
generator can be connected to an internal combustion engine, which is deactivated when the
electrical power of the first power generator is greater or approximately the same size as the
electrical power consumption in the island network.
17. A method for operation control of an electrical island network which comprises:
at least one first power generator, which uses a renewable energy source, wherein the power

generator includes a wind power generator, wherein the wind power generator can be
controlled in terms of its rpm and blade position; at least one second power generator having
a function of a network generator; an internal combustion engine for driving the at least one
second power generator; at least one intermediate storage device for storing electrical
energy which can be coupled to the first power generator, and a controller for controlling
the components of the island network, said method comprising:
feeding the generated energy into the island network via a bus bar;
detecting the power required in the island network by a device connected to the
bus bar; and
coupling the internal combustion engine to the second power generator when the
combustion engine is turned on and decoupling the internal combustion engine from the
second power generator when the combustion engine is turned off; whereby:
in the event of the power consumption in the network being less than the
electrical energy generation capacity of the first power generator, at first electrical energy of
the first power generator is supplied to the intermediate storage device if the intermediate
storage device is not full, so that the first power generator (10) always generates only the
required electric power, under the control by the controller, and
if more energy is consumed in the network than is generated by the first power
generator, the first power generator at first uses the intermediate storage device for
delivering power.
18. The method as claimed in claim 17, wherein the internal combustion engines are
turned on only when the power delivered by the first power generators (10, 12) using
renewable energy sources and/or by the intermediate storage devices (14, 16, 18) falls below
a predetermined threshold for a predetermined period of time.
19. The method as claimed in claim 18, wherein for charging the intermediate
storage device from renewable sources, more energy is generated than is required for the
load on the network.
20. The method as claimed in one of the preceding claims 17-19, wherein for

overcoming frequency instabilities or deviations in the network power frequency from its
desired value, intermediate storage devices are used for delivering power, which can be
frequently and quickly charged or discharged without significant irreversible losses in
capacity.
21. The method as claimed in one of the preceding claims 17-20, wherein an
accumulator block type or a battery storage device is used as the first intermediate storage
devices to support the network when the power required by the island network can be
delivered not at all or only insufficiently from renewable energy sources.
22. The method as claimed in one of the preceding claims 17-21, which involves use
of the second power generator being a synchronous generator as a network generator for a
network-commutated inverter for feeding an alternating current into the electrical island
network, wherein the second power generator works in motor operation and the drive of the
generator is realized by a flywheel and/or by providing electrical energy from a renewable
energy power generator.

Documents:

1199-KOLNP-2004-ABSTRACT.pdf

1199-kolnp-2004-abstract1.1.pdf

1199-KOLNP-2004-CLAIMS.pdf

1199-kolnp-2004-claims1.1.pdf

1199-KOLNP-2004-CORRESPONDENCE 1.1.pdf

1199-KOLNP-2004-CORRESPONDENCE 1.3.pdf

1199-kolnp-2004-correspondence-1.2.pdf

1199-KOLNP-2004-CORRESPONDENCE.pdf

1199-kolnp-2004-correspondence1.1.pdf

1199-KOLNP-2004-DESCRIPTION (COMPLETE).pdf

1199-kolnp-2004-description (complete)1.1.pdf

1199-kolnp-2004-drawings.pdf

1199-kolnp-2004-examination report.pdf

1199-kolnp-2004-form 1.1.pdf

1199-KOLNP-2004-FORM 1.pdf

1199-kolnp-2004-form 18.pdf

1199-kolnp-2004-form 3.pdf

1199-kolnp-2004-form 5.pdf

1199-KOLNP-2004-FORM-27.pdf

1199-kolnp-2004-gpa.pdf

1199-kolnp-2004-granted-abstract.pdf

1199-kolnp-2004-granted-claims.pdf

1199-kolnp-2004-granted-description (complete).pdf

1199-kolnp-2004-granted-drawings.pdf

1199-kolnp-2004-granted-form 1.pdf

1199-kolnp-2004-granted-specification.pdf

1199-kolnp-2004-petition under rule 137.pdf

1199-kolnp-2004-reply to examination report-1.2.pdf

1199-KOLNP-2004-REPLY TO EXAMINATION REPORT.pdf

1199-kolnp-2004-reply to examination report1.1.pdf

1199-kolnp-2004-specification.pdf


Patent Number 247740
Indian Patent Application Number 1199/KOLNP/2004
PG Journal Number 19/2011
Publication Date 13-May-2011
Grant Date 10-May-2011
Date of Filing 18-Aug-2004
Name of Patentee ALOYS WOBBEN
Applicant Address ARGESTRASSE 19, 26607 AURICH
Inventors:
# Inventor's Name Inventor's Address
1 ALOYS WOBBEN ARGESTRASSE 19, 26607 AURICH
PCT International Classification Number H02J 3/28
PCT International Application Number PCT/EP2003/01981
PCT International Filing date 2003-02-27
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 102 10 099.3 2002-03-08 Germany