(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property
`Organization
`International Bureau
`
`1111111111111111 IIIIII IIIII 111111111111111111111111111111111111111111111 IIII IIIIIII IIII 11111111
`
`( 43) International Publication Date
`19 August 2004 (19.08.2004)
`
`PCT
`
`(10) International Publication Number
`WO 2004/070936 Al
`
`(51) International Patent Classification 7:
`F03D 9/00
`
`H02P 9/10,
`
`(21) International Application Number:
`PCT ID K2003/000078
`
`(22) International Filing Date: 7 February 2003 (07.02.2003)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(71) Applicant (for all designated States except US): VESTAS
`WIND SYSTEMS A/S [DK/DK]; Smed Sprensens Vej 5,
`DK-6950 Ringkpbing (DK).
`
`(72) Inventor; and
`(75) Inventor/Applicant (for US only): NIELSEN, John,
`Godsk [DK/DK]; Gammel Ostrupvej 25, DK-8544 Mprke
`(DK).
`
`(81) Designated States (national): AE, AG, AL, AM, AT (util(cid:173)
`ity model), AT, AU, AZ, BA, BB, BG, BR, BY, BZ, CA,
`CH, CN, CO, CR, CU, CZ (utility model), CZ, DE (util(cid:173)
`ity model), DE, DK (utility model), DK, DM, DZ, EC, EE
`(utility model), EE, ES, Fl (utility model), Fl, GB, GD, GE,
`GH, GM, HR, HU, ID, IL, IN, IS, JP, KE, KG, KP, KR, KZ,
`LC, LK, LR, LS, LT, LU, LV, MA, MD, MG, MK, MN,
`MW, MX, MZ, NO, NZ, OM, PH, PL, PT, RO, RU, SC,
`SD, SE, SG, SK (utility model), SK, SL, TJ, TM, TN, TR,
`TT, TZ, UA, UG, US, UZ, VC, VN, YU, ZA, ZM, ZW.
`
`(84) Designated States (regional): ARIPO patent (GH, GM,
`KE, LS, MW, MZ, SD, SL, SZ, TZ, UG, ZM, ZW),
`Eurasian patent (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
`European patent (AT, BE, BG, CH, CY, CZ, DE, DK, EE,
`ES, Fl, FR, GB, GR, HU, IE, IT, LU, MC, NL, PT, SE, SI,
`SK, TR), OAPI patent (BF, BJ, CF, CG, CI, CM, GA, GN,
`GQ, GW, ML, MR, NE, SN, TD, TG).
`
`Published:
`with international search report
`
`(74) Agent: BUDDE, SCHOU & OSTENFELD A/S; Vester
`Spgade 10, DK-1601 Kpbenhavn (DK).
`
`For two-letter codes and other abbreviations, refer to the "Guid(cid:173)
`ance Notes on Codes and Abbreviations" appearing at the begin(cid:173)
`ning of each regular issue of the PCT Gazette.
`
`---------------------------------------------
`
`(54) Title: METHOD FOR CONTROLLING A POWER-GRID CONNECTED WIND TURBINE GENERATOR DURING GRID
`FAULTS AND APPARATUS FOR IMPLEMENTING SAID METHOD
`
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`~ (57) Abstract: The present invention relates to a method and an apparatus for controlling a power-grid connected wind turbine gen-
`0
`erator during grid faults. During grid faults, the stator windings of the wind turbine generator are disconnected from the power grid
`0
`and impedances for dissipating at least part of the power generated by the wind turbine during grid fault condition are connected to
`M the stator windings. In this way, a certain magnetisation of the generator can be maintained and after removal of the grid fault con-
`0 dition, the generator is synchronised to the power grid and the impedances are disconnected and the stator windings are reconnected
`
`: , to the power grid. In this way, it is possible to keep the wind turbine generator at least partly magnetised during grid faults and thus
`;;, ready for delivering power to the power grid, as soon as the grid voltage is re-established after the fault.
`
`SGRE EX1016.0001
`SGRE v. GE, IPR2022-01279
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`METHOD FOR CONTROLLING A POWER-GRID CONNECTED WIND TURBINE
`
`GENERATOR DURING GRID FAULTS AND APPARATUS FOR IMPLEMENTING
`
`SAID METHOD
`
`5
`
`TECHNICAL FIELD
`
`The present invention relates to a method for controlling a power-grid connected
`
`wind turbine generator during grid faults of the kind set forth in the preamble of claim
`
`10
`
`1.
`
`BACKGROUND ART
`
`15
`
`In wind turbine systems it is known to provide some kind of control of the wind
`
`turbine during grid faults. However, the general concept of such control apparatus
`
`aims at stopping the wind turbine by pitching the blades of the wind turbine out of
`
`the wind and disconnecting the generator from the grid. After a certain time, when
`
`the grid voltage has been re-established, the wind turbine is started up in the normal
`
`20
`
`, fashion in order to deliver power to the grid, and the time from disconnection to re-
`
`start of the wind turbine has traditionally been in the order of 1-10 minutes. The
`
`short circuit current contribution from the wind turbine generator has generally been
`
`limited to last approximately 40-50 ms, after which the current from the wind turbine
`
`generator has been zero. Thus, the wind turbine generator does not contribute to
`
`25
`
`the re-establishment of the grid voltage and does not contribute to the short circuit
`
`current in the grid over a longer period of time, which may be necessary in order to
`
`activate the grid protection means for disconnecting the faulty parts of the power
`
`grid.
`
`30
`
`DISCLOSURE OF THE INVENTION
`
`It is the object of the present invention to provide a method for controlling a power(cid:173)
`
`grid connected wind turbine generator during grid faults of the kind referred to
`
`35
`
`above, with which it is possible to keep the wind turbine generator magnetised and
`
`SGRE EX1016.0002
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`2
`
`ready for delivering power to the power grid, as soon as the grid voltage is re(cid:173)
`
`established after the fault, and this object is achieved with a method for controlling a
`
`power-grid connected wind turbine generator during grid faults of said kind, which
`
`according to the present invention also comprises the features set forth in the
`
`5
`
`characterising clause of claim 1. With this method, it is possible to dissipate the
`
`generated power in the impedances, whenever the generated power cannot be
`
`delivered to the power grid, due to fault conditions, such as low voltages or zero
`
`voltages on the power grid, and as soon as the power grid is re-established, the
`
`wind turbine generator can be re-connected to deliver the power to the power grid
`
`1 o
`
`almost instantaneously.
`
`Preferred embodiments of the method according to the invention, the advantages of
`
`which will be evident from the following detailed description, are revealed in the sub(cid:173)
`
`ordinate claims.
`
`15
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`In the following detailed part of the present description, the invention will be
`
`20
`
`explained in more detail with reference to the exemplary embodiments of different
`
`apparatus for implementing the method for controlling a power-grid connected wind
`
`turbine generator during grid faults according to the invention shown in
`
`the
`
`drawings, in which
`
`25
`
`Figure 1 schematically shows a power-grid connected wind turbine generator
`
`comprising a double-fed asynchronous generator, in which the rotor is connected to
`
`the power grid through a back-to-back converter for transferring energy between the
`
`rotor windings and the power grid,
`
`30
`
`Figure 2 schematically shows a possible connection system for connecting the
`
`impedances to the terminals of the wind turbine generator, with possibilities of
`
`connecting the generator in star and delta configuration,
`
`Figure 3 schematically shows another possible arrangement of the connection
`
`35
`
`system for the impedances, in which the impedances can be connected in series
`
`SGRE EX1016.0003
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`3
`
`between the generator terminals and the power grid, and with possibilities of
`
`connecting the generator and the impedances in star and delta configurations,
`
`Figure 4 schematically shows a power-grid connected wind turbine generator
`comprising a double-fed asynchronous generator, in which the rotor is connected to
`
`5
`
`electronically controlled resistors in order to provide a control of the rotor resistance
`
`and a corresponding control of the slip of the generator, and
`
`Figure 5 schematically shows a power-grid connected wind turbine generator
`
`1 o
`
`comprising a generator with a so-called short-circuit rotor.
`
`DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`15
`
`The wind turbine generator system shown in Figure 1 comprises a double-fed
`
`asynchronous generator G, the stator windings of which are normally connected
`through a contactor to the grid indicated by the transformer T. In order to be able to
`
`control the generated power from the generator G, the rotor windings are connected
`to a back-to-back converter comprising a rotor converter, an intermediate DC circuit
`
`20
`
`and a grid converter connected to the power grid via the transformer T. By suitable
`
`control of the rotor converter and the grid converter, the power generation from the
`
`generator G can be controlled in frequency, active power, reactive power, voltage,
`etc.
`
`25
`
`In case of a grid fault, causing a substantial decrease in the voltage on the power
`
`grid, this voltage reduction results in a de-magnetisation of the generator and
`
`corresponding high currents delivered from the stator windings to the grid and in the
`
`rotor windings. However, the rotor converter and grid converter are normally not
`dimensioned to such high currents and accordingly, a crowbar or similar circuit is
`
`30
`
`connected to the rotor windings and is activated, whenever high currents are
`detected in connection with e.g. grid faults. After the demagnetisation of the
`
`generator G, the stator windings are disconnected from the power grid and
`
`connected to stator impedances, providing a load on the generator stator windings
`
`in such a way that the mechanical energy provided from the wind turbine blades to
`the generator can be dissipated in these impedances. After disconnection of the
`
`35
`
`SGRE EX1016.0004
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`4
`
`stator windings from the power grid, the crowbar is disabled and the rotor converter
`
`resumes operation controlling the magnetisation of the generator and the power
`delivery from the stator windings to the impedances connected thereto. Possible
`
`energy delivery from the rotor windings towards the intermediate DC circuit may be
`transmitted further on to the grid through the grid converter, in case a certain grid
`
`5
`
`voltage is present, and vice versa power may be delivered from the grid to the
`intermediate DC circuit. In case the power delivery from the rotor windings cannot
`
`be dissipated by the grid converter connected to the power grid, a DC chopper can
`be inserted in the intermediate DC circuit, which is able to dissipate possible surplus
`
`10
`
`power.
`
`During the fault conditions, the grid converter is preferably controlled to circulate
`reactive short-circuit power towards the grid, and this power is only limited by the
`nominal power of the grid converter. As mentioned above, the power for covering
`the losses in the system can either be delivered from a residual voltage on the
`
`15
`
`power grid or by connecting the generator in such a way that the stator windings are
`more or less short-circuited and the power being delivered from the rotor windings
`through the rotor converter.
`
`20
`
`As mentioned above, and explained in more detail in the following, the short(cid:173)
`circuiting of the stator windings can be performed more or less directly, with or
`
`without impedances inserted in the stator circuit. Furthermore, as also explained in
`more detail in the following, the short-circuiting of the stator including stator
`
`impedances can be performed with the stator windings in star or delta configuration
`
`25
`
`and with the corresponding impedances in corresponding star or delta configuration.
`
`In this way, the configuration of the stator windings and the stator impedances can
`be chosen in such a way that a suitable power dissipation can be achieved and a
`
`major part of the power delivered from the wind can be dissipated in the
`impedances,
`thus avoiding a substantial acceleration of the wind
`turbine.
`Furthermore, the short-circuiting of the stator windings provides the possibility of
`
`30
`
`delivering active and reactive power to the grid from the rotor windings through the
`back-to-back converter.
`
`Under circumstances, in which the risk of over-speeding is low, it may be possible to
`magnetise the generator to approximately 60-100% of rated voltage and to an
`
`35
`
`SGRE EX1016.0005
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`5
`
`amplitude and angle, at which the return of the grid voltage is expected. In this way,
`
`the time for synchronisation is reduced and the stator windings can be reconnected
`
`immediately after return of the grid voltage, in which situation the stator winding
`
`voltages are close to the grid voltages. After the reconnection, the active and
`reactive power can quickly be changed to the values present before the grid fault.
`
`5
`
`During the fault, the speed of the wind turbine can be controlled by dissipating
`
`power in the stator-connected impedances and possibly in the chopper resistance in
`the intermediate DC circuit. Accordingly, the pitching control is primarily only used if
`
`1 o
`
`the rotational speed becomes critical and/or the grid faults and corresponding
`voltage reduction is of a longer lasting character.
`
`During the grid faults, a rotational speed of the wind turbine can be controlled by
`
`means of the pitch system and the rotor converter, and this control can also be used
`for reducing the torsional oscillations on the rotor shaft. Such reduction of the
`
`15
`
`increase in speed and variations in speed makes the re-synchronisation easier. The
`power transmitted to the intermediate DC circuit from the rotor windings through the
`
`rotor converter during deceleration of the generator, can be dissipated in the DC
`
`chopper or possibly be transmitted to the power grid, in case a residual voltage is
`
`20
`
`present therein.
`
`The system for connecting the impedances to the stator windings of the generator
`shown in Figure 2 comprises the normally installed contactors S1, S3, S4 for
`
`providing the possibility of disconnecting the generator from the grid (S1) and for
`connecting the stator windings in star (S2, S4) and delta (S2, S3) configuration.
`
`25
`
`Figure 2 shows two different possibilities for connecting the impedances, using
`
`contactors S5 and S6, respectively, for connecting the impedances coupled in a star
`
`configuration across the stator windings of the generator, said generator windings
`being switchable between a star and delta configuration, respectively. The short
`circuit of the stator windings can be kept separate from the primary current
`
`30
`
`connection, whereby dimensioning of the contactors and wires can be reduced. In
`
`Figure 2, the short circuit can be provided by closing S5 and S4 and opening S1,
`
`whereby the stator is coupled in a star configuration. The short circuit can also be
`
`provided by opening S1 and closing S2, S3 and S5, whereby the stator is in a delta
`
`35
`
`configuration. A further possibility of providing the short-circuiting is to open S2 and
`
`SGRE EX1016.0006
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`6
`
`S3 and closing S4 and S6, again providing a star configuration of the impedances
`
`and the stator windings. A direct short-circuiting of the stator windings can be
`provided by means of the contactors S2, S3, S4, which closing at the same time and
`
`opening of S1 will provide a direct short circuit of the stator windings. Yet a further
`possibility provided by the configurations shown in Figure 2 is a configuration, in
`
`5
`
`which the impedances are coupled in series with the stator windings, and in which
`the stator windings are connected to the grid. This is provided by closing S6, S3 and
`
`S1 and opening S2, S4 and S5. This configuration can be used during disconnecting
`from the grid and/or during reconnection to the grid.
`
`10
`
`15
`
`The arrangement shown in Figure 3 provides other possibilities for the connection of
`
`the impedances. Opening S2 inserts the impedances in series with the stator
`winding terminals U1, V1, W1 by closing S7, and closing S3 or S4 connects the
`
`stator windings in delta or star configuration, respectively. Maintaining S1 closed
`and S8 and S9 opened, active and reactive power can be delivered to the grid, and
`this power can be controlled if the generator is a double-fed asynchronous
`generator, as shown in Figure 1, by controlling the back-to-back converter. A short(cid:173)
`
`circuiting of the stator windings across the impedances can be provided by opening
`
`S1 and closing S8. In this configuration, both the impedances and the stator
`
`20
`
`windings can be coupled between star and delta configuration by means of the
`
`contactors S3, S4, S7, S9.
`
`In a situation where fast re-establishment of the active power has high priority,
`
`power electronic switches may be inserted instead of contactors, in connection with
`
`25
`
`the stator windings. Such switching elements can be provided in such a way that
`
`they are primarily active during fault conditions, to provide a soft and fast
`
`reconnection of the generator windings. As soon as the wind turbine is in a normal
`
`condition, the power electronic switches may be short-circuited by means of
`
`contactors.
`
`30
`
`Above, the invention has been described in connection with a preferred embodiment
`
`thereof, but for a man skilled in the art it is evident that the invention can also be
`used in connection with a wind turbine generator as shown in Figure 4, in which the
`
`rotor windings are connected to an electronically controlled impedance in order to
`provide the possibility of optimising the slip of the generator during operation. Also in
`
`35
`
`SGRE EX1016.0007
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`7
`
`this connection, it is possible to keep the generator at least partly magnetised during
`
`fault conditions by disconnecting the stator windings from the grid and connecting
`impedances to the disconnected stator windings.
`
`5
`
`Furthermore, the invention can also be used in connection with a so-called short(cid:173)
`
`circuit rotor generator, as shown in Figure 5, in which it will also be possible to keep
`the generator magnetised during fault conditions by disconnecting the stator
`
`windings from the grid and connecting suitable impedances to the disconnected
`
`stator windings.
`
`10
`
`In order to improve the synchronisation to the grid, three separate grid voltage
`
`measurements and three separate stator voltage measurements can be used and
`
`furthermore, an encoder can be provided in order to detect the position of the rotor.
`
`SGRE EX1016.0008
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`8
`
`CLAIMS
`
`1. Method for controlling a power-grid connected wind turbine generator during
`
`5
`
`grid faults, said generator comprising a wind turbine driven rotor and a normally grid-
`connected stator, and during normal operation being connected to deliver power to
`the power grid, c h a r a c t e r i s e d by comprising the steps of:
`
`a)
`
`b)
`
`disconnecting the stator windings from the power grid when a fault is detected,
`
`connecting the stator windings to impedances for dissipating between 0 and
`
`100% of the power generated by the wind turbine during grid fault condition,
`
`10
`
`c) maintaining a certain magnetisation of the generator during grid
`conditions, and
`
`fault
`
`d)
`
`after removal of the grid fault condition, synchronising the generator to the
`power grid and disconnecting the impedances and reconnecting the stator
`windings to the power grid.
`
`15
`
`20
`
`2. Method in accordance with claim 1, c h a r a c t e r i s e d by comprising the
`step of connecting the impedances in star or delta configuration and connecting the
`
`stator windings in star or delta configuration, all dependent on measured parameters
`for the wind turbine.
`
`3. Method in accordance with any of the preceding claims, wherein the generator
`
`is a double-fed asynchronous generator,
`
`the rotor windings being normally
`
`connected to the grid through a back-to-back converter for transferring energy
`
`between the rotor windings and the grid in a controlled manner, c h a r a c t e r-
`i s e d by comprising the step of keeping the back-to-back converter connected to
`
`25
`
`the grid during fault condition and controlling the back-to-back converter to deliver a
`controlled short-circuit contribution to the grid during fault condition and to maintain
`
`a certain magnetisation of the generator during grid fault conditions.
`
`30
`
`4. Method in accordance with any of the claims 1-2, wherein the generator is a
`double fed asynchronous generator comprising electronically controlled impedances
`
`connected to the rotor windings, c h a r a c t e r i s e d by comprising the step of
`controlling the electronically controlled impedances connected to the rotor windings
`
`during fault conditions in such a way that a certain magnetisation of the generator is
`maintained during fault conditions.
`
`35
`
`SGRE EX1016.0009
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`9
`
`Apparatus for implementing a method in accordance with claim 1, said
`5.
`apparatus comprising a power-grid connected wind turbine generator comprising a
`
`5
`
`wind turbine-driven rotor and a stator, said stator during normal operation being
`connected to deliver power to the power grid, c h a r a ct e r i s e d by comprising
`means for disconnecting the stator windings from the power grid when a fault is
`detected and means for connecting impedances to the stator windings, said
`impedances being dimensioned to dissipate between 0 and 100% of the power
`generated by the wind turbine during grid fault conditions and comprising means for
`1 o maintaining a certain magnetisation of the generator d~ring disconnection and
`means for synchronising the generator to the grid before reconnection to grid after
`fault clearance.
`
`15
`
`20
`
`25
`
`Apparatus in accordance with claim 5, wherein the means for disconnecting
`6.
`the stator windings from the power grid and the means for connecting the stator
`windings to the impedances comprise contactors.
`
`Apparatus in accordance with claim 5, ch a r act eris e d by the means for
`7.
`disconnecting the stator windings from the power grid and the means for connecting
`the stator windings to the impedances comprising power electronic switches.
`
`Apparatus in accordance with any of the claims 5-7, ch a r act eris e d by
`8.
`further comprising contactors and/or power electronic switches for connecting the
`impedances and/or the stator windings in star and/or delta configuration.
`
`Apparatus in accordance with any of the claims 5-8, c h a r a c t e r i s e d by
`9.
`the generator being a double fed asynchronous generator.
`
`10. Apparatus in accordance with claim 9, c h a r a c t e r i s e d by comprising a
`
`30
`
`back-to-back converter connected between the rotor and the grid.
`
`11. Apparatus in accordance with claim 9, c h a r a c t e r i s e d by comprising
`electronically controlled impedances connected to the rotor windings.
`
`SGRE EX1016.0010
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`10
`
`12. Apparatus in accordance with any of the claims 5-8, c h a r a c t e r i s e d by
`
`the generator being an asynchronous generator with short-circuit rotor.
`
`SGRE EX1016.0011
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`1/2
`
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`
`SGRE EX1016.0012
`
`

`

`WO 2004/070936
`
`PCT/DK2003/000078
`
`2/2
`
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`
`1
`
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`Fig.5.
`
`SGRE EX1016.0013
`
`

`

`INTERNATIONAL SEARCH REPORT
`
`~na l Application No
`PCT /DK 03 /00078
`
`A. CLASSIFICATION OF SUBJECT MATTER
`!PC 7 H02P9/10
`. F0309/00
`
`According to International Patent Classliication (IPC) or to both national classification and IPC
`
`B. FIELDS SEARCHED
`Minimum documentation searched (classification system fallowed by classification symbols)
`IPC 7 H02P F03D H02H H02J
`
`Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched
`
`Electronic data base consulted during the international search (name of data base and, where practical, search terms used)
`EPO-Internal, WPI Data, PAJ
`
`C. DOCUMENTS CONSIDERED TO BE RELEVANT
`
`Category 0 Citation of document, with indication, where appropriate, of the relevant passages
`
`Relevant to claim No.
`
`X
`
`X
`
`A
`
`·,
`
`EP 0 984 552 A· (ASEA BROWN BOVERI)
`8 March 2000 (2000-03-08)
`figure 2
`abstract
`---
`EP 0 378 085 A (TELEFUNKEN SYSTEMTECHNIK)
`18 July 1990 (1990-07-18)
`figure 1
`abstract
`---
`us 5 798 631 A (BHOWMIK SHIBASHIS ET AL)
`25 August 1998 (1998-08-25)
`figure 6
`abstract
`
`-----
`
`1-12
`
`1-12
`
`1-12
`
`□ Further documents are listed in the continuation of box C.
`
`0 Special categories of cited documents ;
`
`"A" document defining the general state of the art which is not
`considered to be of particular relevance
`"E" earlier document but published on or after the international
`filing date
`"L" document which may throw doubts on wiarity claim(s) or
`which is cited to establish the publica ion date of another
`citation or other special reason (as specified)
`"O" document referring ta an oral disclosure, use, exhibition or
`other msans
`"P" document published prior ta the international filing date but
`later than the priority date claimed
`
`Date of the actual completion of the international search
`
`19 September 2003
`Name and mailing address of the ISA
`European Patent Office, P.B. 5818 Patentlaan 2
`NL - 2280 HV Rijswijk
`Tel. (+31-70) 340-2040, Tx. 31 651 epo nl,
`Fax: (+31-70)340-3016
`
`Form PCT//SN210 (second sheet) (July 1992)
`
`IBJ Patent family members are listed in annex.
`
`"T" later document published after the international filing date
`or priority date and not in conflict with the application but
`cited to understand the principle or theory underlying the
`invention
`"X" document of particular relevance; the claimed invention
`cannot be considered novel or cannot be considered to
`involve an inventive step when the document is taken alone
`"Y" document of particular relevance; the claimed invention
`cannot be considered ta involve an inventive step when the
`document is combined with one or more other such docu-
`ments, such combination being obvious to a person skilled
`in the art.
`"&" document member of the same patent family
`
`Date of mailing of the international search report
`08. 1 D. 1003
`
`Authorized officer
`
`BERTI L NORDNEBERG/MN
`
`SGRE EX1016.0014
`
`

`

`~ -na l Application No
`PCT/DK 03/00078
`Publication
`I
`date
`
`Patent family
`member(s)
`19839636 Al
`0984552 A2
`6239511 Bl
`
`02-03-2000
`08-03-2000
`29-05-2001
`
`3900612 Al
`59006454 D1
`378085 T3
`0378085 A2
`3074142 A
`
`12-07-1990
`25-08-1994
`31-10-1994
`18-07-1990
`28-03-1991
`
`INTERNATIONAL SEARCH REPORT
`
`Patent document
`cited in search report
`
`Publication
`date
`
`EP 0984552
`
`A
`
`08-03-2000
`
`I
`
`EP 0378085
`
`A
`
`18-07-1990
`
`DE
`EP
`us
`DE
`DE
`DK
`EP
`JP
`
`us 5798631
`
`A
`
`25-08-1998
`
`NONE
`
`Form PCT/ISN21 O (patent family annex) (July 1992)
`
`SGRE EX1016.0015
`
`