Title of Invention

METHOD FOR OPERATING A WIND POWER INSTALLATION AND A WIND POWER INSTALLATION

Abstract There is provided a method of operating a wind power installation. Under first operating conditions in a normal operating mode the wind power installation delivers a first power to a connected electrical network. That first power is proportional to the wind speed. The wind power installation is controlled in such a way that upon the occurrence of a disturbance it remains on the connected electrical network and delivers to the connected electrical network a second power which is lower than the first power. Upon cessation of the disturbance and under the first operating conditions a third power is briefly delivered to the connected electrical network, the third power being significantly higher than the first power.
Full Text The present invention concerns a method for operating a wind turbine
during a disturbance in the grid network and a corresponding wind turbine.
As the electrical network to which wind turbines or wind power
installations are connected does not always behave in a constant manner but
can also have faults, some methods of controlling wind power installations have
been developed, which have network-supporting properties.
The object of the present invention is to improve network-supporting
methods of operating wind power installations.
Accordingly, the present invention provides a method of operating a
wind power installation, which is proportional to the wind speed, comprising the
step: under first operating conditions in a normal operating mode delivering a
first power to a connected electrical network, which is proportional to the wind
speed, controlling the wind power installation in such a way that it remains on
the connected electrical network when a disturbance occurs and delivers a
second power to the connected electrical network, which is less than the first
power, and under the first operating conditions upon cessation of the
disturbance briefly delivers a third power which is significantly higher than the
first power to a connected electrical network.
The present invention also provides a wind power installation for the
delivery of power to a connected electrical network, comprising: a control unit
for controlling the wind power installation in such a way that under first
operating conditions in normal operating mode a first power is delivered to the
connected electrical network, which is proportional to the wind speed, that the
wind power installation remains on the connected electrical network when a
disturbance occurs and delivers a second power to the connected electrical
network, which is less than the first power, and under the first operating

conditions upon cessation of the disturbance briefly delivers a third power
which is significantly higher than the first power to a connected electrical
network.
Accordingly there is provided a method of operating a wind power
installation. Under first operating conditions in a normal operating mode the
wind power installation delivers a first power to the connected electrical
network. That first power is proportional to the wind speed. The wind power
installation is controlled in such a way that it remains on the connected
electrical network during a disturbance and delivers to the connected electrical
network a second power which is lower than the first power. When the
disturbance ceases and under the first operating conditions a third power is
briefly delivered to the connected electrical network, the third power being
significantly higher than the first power.
In that way a wind power installation can be controlled in such a fashion
that, after the cessation or elimination of a disturbance the wind power
installation intervenes in network-supporting relationship and for a short time
feeds an increased level of power into the connected electrical network.
In accordance with a configuration of the invention the wind power
installation has an intermediate storage means and the increased value of the
third power is obtained by a control of the intermediate storage means.
Accordingly for a short time after cessation of the disturbance the wind power
installation provides a higher level of power which is higher than that power
which is obtained in the normal operating mode under the given operating
conditions.
The invention also concerns a wind power installation for delivering
power to a connected electrical network. The wind power installation has a
control unit for controlling the wind power installation. Under first operating

conditions in a normal operating mode a first power is delivered to the electrical
network, which is proportional to the wind speed. When a disturbance occurs a
second power is delivered, which is less than the first power. After the
cessation or upon the cessation of the disturbance, under the first operating
conditions, a third power is delivered which is significantly higher than the first
power.
Accordingly both the second and also the third power is disproportional
to the wind speed while the first power is proportional to the wind speed.
Further configurations of the invention are subject-matter of the
appendant claims.
The invention is based on the notion that the delivered power of a wind
power installation, after the elimination of a fault in the network, is briefly
increased in order in that way to intervene in network-supporting relationship.
That briefly increased delivery of power is implemented for example by suitable
control of the dc voltage intermediate circuit or chopper. In the normal operating
mode, under the corresponding operating conditions, a wind power installation
delivers a first power to a network. When a disturbance occurs in the network
the delivered power is reduced and, when the disturbance is eliminated, an
increased power is delivered for a short period of time. In that situation that
briefly increased level of power is markedly higher than the power delivered
under the given operating conditions, that is to say, after the elimination of a
fault significantly more power is delivered for a short time than in the normal
operating mode under the operating conditions.
The invention is described in greater detail hereinafter by means of the
embodiments by way of example and the accompanying drawings in which:
Figure 1 shows an energy network with some energy generating units,

Figure 2 shows a voltage collapse in a system as shown in Figure 1
because of a fault,
Figure 3 shows a voltage profile after elimination of a fault in a system
as shown in Figure 1,
Figure 4 shows the fundamental structure of a wind power installation
according to the invention,
Figure 5 shows the fundamental structure of a test system,
Figures 6 to 9 show measurement results for the test system shown in
Figure 5,
Figures 10 to 13 show further test results for the system shown in Figure
4,
Figures 14 and 15 show analytical results of the system shown in Figure
1, and
Figures 16 and 17 show further analytical results.
The term 'integration of embedded generation' refers hereinafter to the
capacitance of energy units which are integrated in a part of an energy system,
which exceeds the energy supplied by another part of the system.
Figure 1 shows the structure in principle of an energy generation
network with some generators G.

A 'ride-through' of embedded generation units means in this context that
the generation units remain on the network and feed a short-circuit power to the
network during the occurrence of a fault in the network. Active and reactive
power are also fed to the network immediately after the elimination of a fault.
The reasons for the 'ride-through' demands in respect of the
transmission access codes which are increasingly established by the network
operators represent the following:
Figure 2 shows a diagrammatic structure of an energy generation
network, a diagram for illustrating a voltage collapse because of a fault in the
network.
Figure 3 shows a diagrammatic structure of an energy generation
system and the voltage profiles prior to and after the elimination of a fault. In
that case the upper curve represents the situation where generators G are
arranged in the network while the lower curve represents the situation without
generators.
In that respect Figure 2 shows three different voltage curves with a
voltage collapse. The voltage curve S3 shows the status quo of wind power
installations at the time. The voltage curve S2 shows the case of wind power
installations with a ride-through capability and the voltage curve S1 shows gas
turbines with synchronous generators.
The voltage collapse region is intended to be limited to avoid an
undervoltage which is induced by generation units being separated off
(avoidance of chain-active power-deficits). The build-up stability is to be
maintained or improved if the error location decouples parts of the system
(synchronisation power depends on the square of the voltage Vsyn in Figure 2).
A given fault current level should be provided (maintenance of the protection

criterion and if possible setting of protection relays). An additional reactive
power requirement by the generation units after the elimination of a fault should
be avoided (risk of voltage collapse and overloading of the equipment by virtue
of the cascading reactive power requirement in the case of a significant motor
load). The stability reserve after the elimination of a fault should be improved
(synchronisation of the power depends as shown in Figure 3 on the square of
the voltage Vsyn).
The operators of the energy supply networks must keep large power
systems stable during the normal and fault states. System models are applied
in that respect in this context for various purposes. The presence of suitable
models is therefore essential for the network operators, in particular in cases
involving great integration of embedded generation.
Dynamic system analysis is used in that respect to determine
electromechanical transient build-up states after a disturbance to the system.
That is effected used primarily in the region of transient stability analysis. The
following characteristics for the development of corresponding system models
are:
Calculation of current/voltage/power/power factor/torque/rotor angle in
dependence on the time in a time range of about 100 ms after disturbances
(electromagnetic transients have disappeared and the electromagnetic parts of
the system are virtually in equilibrium with the exception of very slow
electromagnetic modes) to some minutes (electromechanical transients have
disappeared and the electromechanical parts of the system are also in
equilibrium). Thermal transients are generally not covered by the system
model.
Assumption of symmetrical system conditions including a fault
impedance during the specified time range.

Application of equilibrium models for the equipment of the electrical
network or in the case of larger rotating machines (synchronous or induction
machines) and application of order-reducing dynamic models.
Accordingly that affords the following for the electrical part of the system:
mathematical (phasor) models for the electrical equipment with the
exception of larger machines (for those machines there are models of
mathematical and differential equations);
phasors with time-dependent square root values (RMS values), phase
angles and sometimes a time-dependent system frequency. While
square root values and the phase angle for all phasors can be different a
single but not necessarily constant frequency is assumed for all phasors;
symmetrical models for the electrical part of the system, which can be
represented by a single phase (positive sequence representation);
application of dynamic models for equipment which controls the system
movement in the relevant time range (for example voltage and current
controller); and
application of dynamic models for the drive machine (for example
mechanical inertia, torque production).
Models which fulfil the above-listed characteristics are referred to as
'RMS-dynamic' or 'mid-term' models. Models of that type permit a
representation of large energy systems by maintenance of most of the
relevant properties which monitor the dynamic modes of the system.

Accordingly system analysis software used by network operators is often
based on that approach.
It is a generally accepted requirement that the system models must be
the same. Accordingly all models of the various components of the energy
system should be of the same general type.
RMS-dynamic models for thermal generation units, transmission
devices, protection systems, network control equipment etc are generally
already available and correspondingly implemented. Thus the required models
for wind power installations should represent models of the RMS-dynamic type
as stated above.
Set forth hereinafter are the specific requirements for models of wind
power installations.
At the present time the general regulations relating to connecting
specific embedded generation units to the high-voltage networks in Germany
are drawn up by the 'Verband Deutscher Netzbetreiber VDN' ['Association of
German Network Operators']. Those regulations govern the technical details of
network codes under the UCTE (transmission and distribution for units under
the German energy feed statute).
In addition the German network operators specify the requirements for
wind power installation models for various system analysis purposes. The
following requirements have been specified hitherto for dynamic fault studies:
The turbine model is coupled to the positive sequence RMS-dynamic
network model by way of phasors for the terminal voltage and the current.
It applies for symmetrical three-phase faults with residual terminal
voltages of 0.1 ... 0.8 pu, for a fault elimination time of 0.1 to 3 sec, and for the

time range of approximately 100 ms (after the transients have disappeared) to
approximately 5 sec after faults (the critical range for transient stability). A
model which can be used for a large number of turbines and can thus be
applied to limited enlargements (insofar as acceptable in respect of accuracy).
An option for specifying an initial operating point (energy to be produced). A
possible manner of implementation of the model in already existing system
analysis software with restricted possibilities for user-defined components.
The basic design and the function of the wind power installations
according to the invention are described hereinafter.
Figure 4 shows a basic structure of the wind power installations
according to the invention. In this respect in particular a wind power installation
with two power modules is illustrated.
The wind power installation is equipped with three pitch-controlled rotor
blades. The rotor is operated with an optimum pitch angle until the nominal
speed of the motor is reached (with the exception of the starting conditions). If
the speed exceeds the nominal speed by virtue of an increasing wind or by
virtue of losses in the network (fault ride-through), the pitch control unit limits
the speed and operates the wind power installation under safe conditions.
The rotor moves a six-phase synchronous generator directly - without
transmission - . The rotor is electrically excited. The excitation system is
connected to the dc voltage bus with the exception of the starting phase of the
wind power installation. The excitation control is part of the control system of
the wind power installation. The generator supplies a variable voltage to a dc
voltage bus.
The dc voltage-ac voltage intermediate circuit has power modules. The
number of modules depends on the structure of the wind power installation.

The dc voltage intermediate circuit of each module includes a chopper for
various purposes, balancing capacitors, an IGBT inverter and a filter assembly.
The (sole) transformer is also part of the filter design.
From the point of view of the network the power modules under normal
conditions and under slowly changing conditions behave like controlled
symmetrical current sources (in respect of the fundamental frequency of the
currents). The square root (RMS) of the currents and the phase angle thereof is
controlled and held in symmetrising relationship.
The inverter is controlled in accordance with the various parameters of
the wind power installation. As the control of the inverter represents a
substantial part of the overall control of the wind power installation, the
possibility of isolating that control is very limited. That is the reason for a given
inevitable enlargement of the model.
Fast control is necessary for example for the electronic power
apparatuses of the inverter, the choppers etc. That is achieved by various
distributed controllers C as shown in Figure 4. In the RMS time range most of
the controllers can be viewed as being disposed in the equilibrium condition.
The voltage and power control and some other control tasks relate to the
dynamic conditions of the wind power installation in the RMS time range. Those
controllers must be explicitly taken into consideration when forming the model.
The MPU and the specific controller interface as shown in Figure 4 illustrate the
equipment for that control level.
Standard communication with external interfaces and correction of
settings, such as for example power limitation Pmax and the phase angle, are
obtained by means of the SCADA unit. That system is not provided for use for

fast network control purposes. The fast control standards use specific controller
interfaces.
The fundamental behaviour during symmetrising system faults is
described hereinafter.
The test system for the development and testing of the ride-through
properties of the wind power installations according to the invention is
described by the following main features. There is provided a reduced-size
generator/rectifier/dc voltage intermediate circuit/inverter/filter system with an
original electronic system for the development and testing of the underlying
design concept, the control strategies and the algorithm, the software and the
items of electronic equipment. A flexible network allows various kinds of system
configurations and faults. A severely noisy PCC gives rise to hard conditions for
measuring apparatuses and control components.
A weak PCC in terms of short-circuit power and frequency causes
difficult operating conditions for a system control (concept as well as algorithm
and software).
Figure 5 shows a configuration of the test system for ride-through tests.
The following fault was initiated at the indicated location:
A symmetrical 3-phase fault F with zero impedance is of a duration of
770 ms.
Elimination is effected by a phase jump of approximately -8°. The short-
circuit power ratio is reduced from approximately 30 to 15.
The currents I in the inverter and also the terminal voltages V (line to
earth) is measured at the locations indicated by the arrows. The results of that

test are shown in Figures 6 to 9. The sampling rate was selected at 3 kHz. Pre-
filters (anti-aliasing) were not used in this case.
In Figure 6 the current I and the voltage V are shown in dependence on
samplings. In this case a fault occurs approximately between 1500 and 3500
samplings. During the occurrence of that fault voltage collapse takes place.
Figure 7 shows the active power Pw and the reactive power Pb. In this
case the active power Pw is represented by the upper curve while the lower
curve represents the reactive power. Here a fault occurs approximately after
1800 samplings to about 4000 samplings. During the occurrence of the fault the
active power is reduced, more specifically from about 0.6 to below 0.2 pu. After
elimination of the fault, that is to say approximately at 4000 samplings, the
active power is briefly increased. That active power peak goes to 1.2 pu. The
reactive power Pb is also increased after elimination of the fault and then
brought again substantially to zero.
Figure 8 shows a portion of the representation in Figure 6. In this respect
it can be seen that the current dies away after the occurrence of the fault and
thereafter builds up again. In the case of the voltage configuration V however
the situation is different as the voltage configuration fluctuates greatly.
Figure 9 shows a portion from Figure 6 after elimination of the fault. It
can be seen here that the current oscillates while the voltage initially remains at
one level and then after about 3660 samplings also begins to oscillate.
The power modules of the original size, as stated hereinbefore and as
shown in Figure 4, were suitably tested in the test devices. The tests carried
out were conducted firstly to analyse the loading of all power-electronic
components during and after symmetrical system faults.

The corresponding test results are shown in Figures 10 to 13.
Figure 10 shows the terminal voltage in relation to time. Here a fault
occurs at about 3.4 seconds and lasts up to about 6.8 seconds. The above-
described voltage collapse occurs during the fault.
Figure 11 shows the current in relation to time during the occurrence of a
fault. While a voltage collapse occurs as shown in Figure 10 the current rises
during the fault.
Figure 12 shows the active power in relation to time during the
occurrence of the fault. During the fault between 3.4 and 6.8 seconds the active
power falls to zero. After elimination of the fault there is a peak in the active
power.
Figure 13 shows a portion from Figure 12 at the time of elimination of the
fault. The peak in the power can be clearly seen here. The power peak goes to
over 1.2 pu. Thereafter the active power falls back to a value of between 0.7
and 0.8 pu.
The test system shown in Figure 5 was modelled in accordance with the
system analysis approach which is usually employed for transients and also for
dynamic system analyses.
The model of the test system has a 6-phase generator with harmonic
flux connection in the air gap (FEM-based parameter identification), a stator
rectifier and rotor excitation devices including controller, a dc voltage
intermediate circuit including all power electronic components (choppers) and
controller, an inverter including controller, a relevant MPU functionality, a filter,
a transformer including vector group and earthing, and lines including earth (full
matrix representation).

That system model is a non-linear full-state hybrid model
(continuous/discrete hybrid model) in the time range. The continuous part has
eigenvalues in various time scales and must be resolved by numerical
integration methods.
The ride-through scenario which is applied for the ride-through test
shown in Figure 5 was analysed with that model. However the fault duration
was limited to 100 ms by curtailing the time-consuming numerical integration
procedure. In contrast to the active test system the equivalent system
generator was not disturbed stochastically in order to depict the noise of the
network.
Figures 14 and 15 show selected analytical results. The analytical
results can be compared to the measurements of Figures 6 to 9. In interpreting
that comparison, the shortened fault duration and the noise of the network must
also be taken into consideration.
Figure 15 shows the active power upon the occurrence of a fault. Here
too it is possible to see the clear collapse in the active power during the fault,
that is to say between 0.05 and 0.15 seconds. After elimination of the fault at
0.15 seconds there is in this case also a briefly increased delivery of active
power, in which respect that delivered active power can be up to 1.2 pu.
As already described above the network operators often use software
packages for dynamic system analysis based on the RMS-dynamic
approaches. That type has significantly fewer dynamic states compared to
transient models and can be developed using order reduction.
An RMS-dynamic model which takes account of all relevant structural
aspects in this area and which satisfies the above-stated criteria was thus
developed for the test system.

Figures 16 and 17 represent the corresponding analysis results for the
same ride-through scenario as the measured scenario. The results can be
compared to the measurement results shown in Figures 6 and 7 and the results
from the transient analysis shown in Figures 14 and 15.
Figure 17 represents the active power calculated from the current and
voltage configurations shown in Figure 16. In this case also it is possible to see
a briefly increased active power delivery directly after elimination of the fault.
The wind power installations according to the invention thus provide a
ride-through option, provide a short-circuit power of about 1.0 to 1.2 pu on the
standardised power axis and produce active and reactive power immediately
after the elimination of a fault. The production of active power is effected by
virtue of remaining on the network for the entire time without interruption.
For dynamic system analysis purposes there are provided models based
on a positive sequence RMS approach and transfer function representations.
For situations which are not covered by those models (transient phenomena
and phase-unbalance faults), detailed models are required.
The above-described, briefly significantly increased generator power is
delivered substantially by the generator and the intermediate circuit. That effect
does not represent a system-inherent behaviour but must be implemented by
suitable control of the intermediate circuit.
In a normal operating situation in which the generator produces for
example 0.6-times the nominal power the synchronous machine operates with
a pole rotor which is excited with direct current and which produces a rotating
field in the stator which in turn induces voltages in the stator windings. In that
case the pole rotor leads the field rotating in the stator by the pole rotor

displacement angle. Upon the occurrence of a fault in the network for example
with a voltage collapse there is a reduced power delivery to the network, which
also leads to a rise in the intermediate circuit voltage. Provided in the
intermediate circuit is a so-called chopper which dissipates the excess power
by way of load resistors or consumes it in order to prevent overspeeding of the
rotor. That increase in the intermediate circuit voltage however also has an
effect on the generator. As the control of the chopper also determines the level
of the intermediate circuit voltage it also has a certain influence on the terminal
voltage of the generator so that this voltage, in the wind power installations
according to the invention, is somewhat higher than in normal operation.
In the generator that results in a slightly higher rotor speed which is
reflected in the mechanical system comprising rotor blade, hub and pole rotor.
At the same time however the rotor displacement angle also becomes
somewhat less. As that results in a somewhat lower generator moment, a
somewhat higher speed is produced.
When the network reverts to the normal operating conditions, at the first
moment a higher level of power flows into the network by virtue of the higher
intermediate circuit voltage, through the inverters. Since as a result the
intermediate circuit voltage falls, the terminal voltage of the generator also
changes, the rotor displacement angle increases again, the generator moment
increases and the rotary speed of the mechanical system again becomes
slightly less. For a relatively short period of about 100 - 200 milliseconds the
generator delivers a higher power, by virtue of the slightly higher speed, until
the mechanical system is braked to a corresponding degree. The energy
produces the additional power which can be delivered into the network.
The briefly increased power delivery is thus effected by specific targeted
control of the chopper.

I CLAIM :
1. A method of operating a wind power installation, which is proportional
to the wind speed, comprising the step:
under first operating conditions in a normal operating mode delivering a
first power to a connected electrical network, which is proportional to the wind
speed, controlling the wind power installation in such a way that it remains on
the connected electrical network when a disturbance occurs and delivers a
second power to the connected electrical network, which is less than the first
power, and under the first operating conditions upon cessation of the
disturbance briefly delivers a third power which is significantly higher than the
first power to a connected electrical network.
2. A method as claimed in claim 1 wherein the third power represents a
short-circuit power.
3. A method as claimed in claim 1 or claim 2 wherein the wind power
installation has an intermediate storage means and the increased third power is
obtained by control of the intermediate storage means.
4. A method as claimed in claim 3 wherein the wind power installation
has a dc voltage intermediate circuit as the intermediate storage means and
the increased third power is obtained by control of the dc voltage intermediate
circuit.
5. A method as claimed in claim 4 wherein the dc voltage intermediate
circuit has a chopper and the increased third power is obtained by control of the
chopper in the dc voltage intermediate circuit.

6. A method as claimed in claim 3 wherein the rotation of the generator
of the wind power installation is used as the intermediate storage means and
the increased third power is obtained by control of the rotation.
7. A wind power installation for the delivery of power to a connected
electrical network, comprising:
a control unit for controlling the wind power installation in such a way
that under first operating conditions in normal operating mode a first power is
delivered to the connected electrical network, which is proportional to the wind
speed, that the wind power installation remains on the connected electrical
network when a disturbance occurs and delivers a second power to the
connected electrical network, which is less than the first power, and under the
first operating conditions upon cessation of the disturbance briefly delivers a
third power which is significantly higher than the first power to a connected
electrical network.
8. A wind power installation as claimed in claim 7 wherein the wind
power installation has an intermediate storage means and the control unit is
adapted to obtain the increased third power by control of the intermediate
storage means.
9. A wind power installation as claimed in claim 8 comprising a dc
voltage intermediate circuit as the intermediate storage means, wherein the
control unit is adapted to obtain the increased third power by control of the dc
voltage intermediate circuit.
10. A wind power installation as claimed in claim 9 wherein the dc
voltage intermediate circuit has a chopper and the increased third power is
obtained by control of the chopper in the dc voltage intermediate circuit.
11. A wind power installation as claimed in claim 8 wherein the rotation
of the generator of the wind power installation is used as the intermediate storage means and the increased third power is obtained by control of the
rotation.

Documents:

00482-kolnp-2006-abstract.pdf

00482-kolnp-2006-claims.pdf

00482-kolnp-2006-description complete.pdf

00482-kolnp-2006-drawings.pdf

00482-kolnp-2006-form 1.pdf

00482-kolnp-2006-form 3.pdf

00482-kolnp-2006-form 5.pdf

00482-kolnp-2006-gpa.pdf

00482-kolnp-2006-international publication.pdf

00482-kolnp-2006-pct request.pdf

00482-kolnp-2006-priority document.pdf

482-KOLNP-2006-ABSTRACT 1.1.pdf

482-KOLNP-2006-AMANDED CLAIMS.pdf

482-KOLNP-2006-CORRESPONDENCE 1.1.pdf

482-kolnp-2006-correspondence-1.1.pdf

482-KOLNP-2006-CORRESPONDENCE.pdf

482-KOLNP-2006-CORRESPONDENCE_1.1.pdf

482-KOLNP-2006-DESCRIPTION (COMPLETE) 1.1.pdf

482-KOLNP-2006-DRAWINGS 1.1.pdf

482-KOLNP-2006-EXAMINATION REPORT REPLY RECIEVED.pdf

482-kolnp-2006-examination report.pdf

482-KOLNP-2006-FORM 1 1.1.pdf

482-kolnp-2006-form 18.pdf

482-KOLNP-2006-FORM 2.pdf

482-KOLNP-2006-FORM 3 1.1.pdf

482-KOLNP-2006-FORM 3.1.1.pdf

482-KOLNP-2006-FORM 3.1.2.pdf

482-kolnp-2006-form 3.pdf

482-kolnp-2006-form 5.pdf

482-KOLNP-2006-FORM-27.pdf

482-kolnp-2006-gpa.pdf

482-kolnp-2006-granted-abstract.pdf

482-kolnp-2006-granted-claims.pdf

482-kolnp-2006-granted-description (complete).pdf

482-kolnp-2006-granted-drawings.pdf

482-kolnp-2006-granted-form 1.pdf

482-kolnp-2006-granted-form 2.pdf

482-kolnp-2006-granted-specification.pdf

482-KOLNP-2006-OTHERS 1.1.pdf

482-KOLNP-2006-OTHERS DOCUMENTS.pdf

482-KOLNP-2006-OTHERS_1.1.pdf

482-KOLNP-2006-PA.pdf

482-kolnp-2006-reply to examination report.pdf

abstract-00482-kolnp-2006.jpg


Patent Number 247398
Indian Patent Application Number 482/KOLNP/2006
PG Journal Number 14/2011
Publication Date 08-Apr-2011
Grant Date 04-Apr-2011
Date of Filing 02-Mar-2006
Name of Patentee WOBBEN ALOYS
Applicant Address ARGESTRASSE 19, 26607, AURICH
Inventors:
# Inventor's Name Inventor's Address
1 WOBBEN ALOYS ARGESTRASSE 19, 26607, AURICH
PCT International Classification Number H02J 3/38
PCT International Application Number PCT/EP2004/010616
PCT International Filing date 2004-09-22
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 03 021 439.9 2003-09-23 Germany