WO2010066892A2 - Control method and apparatus - Google Patents

Control method and apparatus Download PDF

Info

Publication number
WO2010066892A2
WO2010066892A2 PCT/EP2009/066974 EP2009066974W WO2010066892A2 WO 2010066892 A2 WO2010066892 A2 WO 2010066892A2 EP 2009066974 W EP2009066974 W EP 2009066974W WO 2010066892 A2 WO2010066892 A2 WO 2010066892A2
Authority
WO
WIPO (PCT)
Prior art keywords
grid
point
characteristic
reactive
reactive current
Prior art date
Application number
PCT/EP2009/066974
Other languages
French (fr)
Other versions
WO2010066892A3 (en
Inventor
Jorge Martinez Garcia
Original Assignee
Vestas Wind Systems A/S
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Vestas Wind Systems A/S filed Critical Vestas Wind Systems A/S
Priority to CN200980156704.5A priority Critical patent/CN102318157B/en
Priority to EP09795963.9A priority patent/EP2376773B1/en
Priority to ES09795963.9T priority patent/ES2581427T3/en
Publication of WO2010066892A2 publication Critical patent/WO2010066892A2/en
Publication of WO2010066892A3 publication Critical patent/WO2010066892A3/en

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/70—Regulating power factor; Regulating reactive current or power
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03D—WIND MOTORS
    • F03D9/00—Adaptations of wind motors for special use; Combinations of wind motors with apparatus driven thereby; Wind motors specially adapted for installation in particular locations
    • F03D9/20—Wind motors characterised by the driven apparatus
    • F03D9/25—Wind motors characterised by the driven apparatus the apparatus being an electrical generator
    • F03D9/255—Wind motors characterised by the driven apparatus the apparatus being an electrical generator connected to electrical distribution networks; Arrangements therefor
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/12—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load
    • H02J3/16—Circuit arrangements for ac mains or ac distribution networks for adjusting voltage in ac networks by changing a characteristic of the network load by adjustment of reactive power
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/381—Dispersed generators
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J3/00—Circuit arrangements for ac mains or ac distribution networks
    • H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
    • H02J3/46—Controlling of the sharing of output between the generators, converters, or transformers
    • H02J3/50—Controlling the sharing of the out-of-phase component
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/04—Control effected upon non-electric prime mover and dependent upon electric output value of the generator
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P9/00—Arrangements for controlling electric generators for the purpose of obtaining a desired output
    • H02P9/10—Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load
    • H02P9/102—Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load for limiting effects of transients
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2300/00—Systems for supplying or distributing electric power characterised by decentralized, dispersed, or local generation
    • H02J2300/20—The dispersed energy generation being of renewable origin
    • H02J2300/28—The renewable source being wind energy
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P2101/00—Special adaptation of control arrangements for generators
    • H02P2101/15—Special adaptation of control arrangements for generators for wind-driven turbines
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/72—Wind turbines with rotation axis in wind direction
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/70—Wind energy
    • Y02E10/76—Power conversion electric or electronic aspects
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
    • Y02E40/30—Reactive power compensation

Definitions

  • the present disclosure relates to a method for controlling a wind power generation system connected to a grid at a point of connection, wherein the system is devised to feed reactive power to the grid in transient conditions in order to improve grid stability.
  • the disclosure is further related to a corresponding controller.
  • One object of the present disclosure is therefore to provide a control method of the initially metioned kind with improved stability.
  • This object is achieved by means of a method as defined in claim 1. More specifically the method involves determining a Q-V characteristic for the grid at the point of connection, and controlling the feeding of reactive power based on the Q-V characteristic. In this way it can be avoided that the controller drives the reactive current to a point where the voltage collapses as a result thereof. This improves the stability of the system.
  • the method may further involve determining a nose point for the Q-V characteristic and determining a minimum reactive current, lomin, which is safe from the nose point.
  • the controlling of the feeding of reactive power may then include keeping the reactive current higher than the minimum reactive current.
  • the Q-V characteristic may be determined by injecting a disturbance at the point of connection. This means that the Q-V characteristic can be determined at regular intervals, as there is no need to await a disturbance in the grid.
  • the feeding of reactive power to the grid may be controlled by controlling rotor currents of a double fed induction generator, DFIG, or, alternatively by controlling switches of an AC/DC/AC converter configuration connecting a generator with the grid.
  • a controller carrying out the method may be readily integrated in the control loops of any such system, since means for controlling the reactive power is already provided for therein.
  • the method may be used both in transient and steady state conditions, in order to improve grid stability.
  • a controller comprising functional blocks capable of carrying out the actions of the method implies corresponding advantages and may be varied correspondingly.
  • Such a controller may be included in a wind power generation system.
  • Fig 1 illustrates a wind power generating system connected to a grid.
  • Fig 2 illustrates a Q-V characteristic.
  • Fig 3 illustrates a flow chart for a control method.
  • Fig 4 shows a configuration of a wind power generation system with a doubly fed induction generator.
  • Fig 5 shows a configuration of a wind power generation system with a full converter.
  • Fig 6 illustrates schematically a wind power generation system controller.
  • Fig 1 illustrates a wind power generating facility 1 connected to a grid 3.
  • the facility comprises a turbine 5, including a plurality of blades and being mounted on a tower 7 and connected, often via a gearbox, to a generator in the tower.
  • the generator in turn is connected to the grid 3 with a three phase connection (zero connection not shown) at a point of connection 9, often via a switched converter (not shown), and usually via one or more transformers (not shown).
  • the wind power generating facility 1 has only one turbine 5.
  • a wind power generating facility 1 in the context of this disclosure may comprise a plurality of turbines, which may each be mounted on a tower.
  • the wind power generating facility 1 may thus be a wind farm.
  • vertical axis turbines are conceivable.
  • LVRT low voltage ride through
  • the power generating facilities should be able to supply reactive power to or absorb reactive power from the grid during a transient condition. For instance, if a voltage dip occurs due to a fault on one or more grid phases, the power generating facility should be able to supply reactive current to the grid in order to improve stability.
  • Reactive power regulating means 11 is therefore connected to the grid 3 at the point of connection.
  • the reactive power regulating means 11 may be integrated with the energy conversion link in the system or may be provided as a separate auxiliary unit.
  • a transient condition refers not only to voltage dips in the grid, but to any sudden change in grid parameters that can be affected by injecting or absorbing reactive power to or from the grid at the point of connection. Thus, for instance a voltage surge is also included.
  • Fig 2 illustrates a Q-V characteristic 13 for a typical connection point of a grid.
  • Q relates to the amount of reactive power (VAr) injected to or absorbed from the grid by adding or subtracting reactive current at the point of connection to the grid.
  • V relates to the grid voltage at the point of connection.
  • the Q-V characteristic shows the relation between the two parameters. The characteristic is, for higher added reactive currents, relatively linear. See the Q-V characteristics to the right of the voltage V relating to the point Q mm . For these relatively higher currents in the illustrated charcteristics the voltage increases with increasing added reactive current. However, the Q-V curve as a whole has a parabolic nature.
  • a point 15 of the Q-V characteristic dV/dQ is zero. This point is called a nose point 15, and the present charcteristics of the grid determines where the nose point 15 is situated. Below this point, an increase in added reactive current will decrease the voltage instead of increasing it, and such an increase in added reactive current would consequently worsen the state of the grid.
  • Fig 3 illustrates a flow chart for a control method.
  • the Q-V characteristic for the grid at the point of connection is determined 21.
  • the Q-V-curve in the desired operating range resembles a parabolic function with the form:
  • the parameters a, b, and c can be determined. It is however also possible to utilise other disturbances in the system, e.g. a voltage drop to determine the characteristic.
  • the nose point for the Q-V characteristic is determined 23. This can be done simply by finding the point on the characteristic where dQ/dV is zero which is a very simple operation.
  • a minimum reactive current, lQ m m is determined 25.
  • This current should be safe from the nose point, i.e. in some distance from and above the nose point, typically meaning that lQ mm is 110% of the current that corresponds to the nose point.
  • this percentage is only an example and may be varied in accordance with grid stability requirements or operator settings.
  • the operation is kept at points of the Q-V characteristic at reactive currents IQ greater than the minimum reactive current lQ mm so that the voltage V is kept higher than the voltage corresponding to the nose point.
  • the controller is set 27 to provide lQ mm as a minimum reactive current, such that the added reactive current is kept higher than the level providing the minimum reactive current even during a LVRT condition.
  • a reactive power regulating means 11 should comprise functional blocks for carrying out these actions.
  • Fig 6 illustrates a regulator comprising such blocks, namely a Q-V characteristics detector 51 , a nose point detector 53, an lQ mm determination unit 55, and a current controller 57.
  • Such blocks may typically be software implemented as routines executed on a digital signal processor even though various hardware configurations, e.g. utilising applications specific integrated circuits, ASICs, would in principle also be conceivable.
  • Fig 4 shows a power conversion configuration with a doubly fed induction generator 31 , connected to a wind turbine (not shown).
  • a slip ring may be used to feed currents 33 to windings in the rotor.
  • the rotor currents 33 may be provided by means of an AC/DC/AC converter 35 connected to the generator 31 output.
  • Such doubly fed induction generators allow the rotor of the generator to rotate with a varying rotation speed, out of synchronism with the grid frequency.
  • a transformer (not shown) may be placed between the grid 3 and the generator 31.
  • the amount of active and reactive power that is fed to the grid may be controlled by controlling the currents fed to the rotor windings of the generator.
  • the regulator 11 may then have the converter 35 as an integrated part, generating the rotor currents that provide the desired amount of added reactive power.
  • Fig 5 shows a power conversion configuration for a synchronous generator 41 , connected to a wind turbine (not shown). Then, a permanent magnet synchronous generator PMSG 41 is used together with an AC/DC/AC converter configuration 43, 45, 47.
  • the converter configuration comprises an AC/DC converter 43, connected to the stator windings of the generator 41.
  • the AC/DC converter 43 feeds DC power to a filter capacitor 45.
  • a DC/AC converter 47 feeds power from the filter capacitor 45 to the grid 3.
  • the amount of active and reactive power supplied to the grid may be controlled by controlling the switches of the DC/AC converter in the configuration, which forms part of the reactive power regulator 11.
  • the reactive power regulator 11 may include a static VAR capacitor bank may be used to control the reactive power produced.
  • a rotating compensator could also be used in the same way. The present disclosure is not limited to the described embodiments, it may be altered and varied in different ways within the scope of the appended claims.

Abstract

The present disclosure relates to method and a controller for controlling a wind power generation system. The system is connected to a grid at a point of connection, and is devised to feed reactive power to the grid in order to improve grid stability. A Q-V characteristic is determined for the grid at the point of connection as well as a nose point for the Q-V characteristic. A minimum reactive current, lQmm, which is safe from the nose point, is determined, and the feeding of reactive power is controlled such that the reactive current is kept higher than the minimum reactive current. In this way it is made sure that the reactive current does not make the Q-V characteristic reverse, and thereby the stability of the system is improved.

Description

CONTROL METHOD AND APPARATUS
Technical field
The present disclosure relates to a method for controlling a wind power generation system connected to a grid at a point of connection, wherein the system is devised to feed reactive power to the grid in transient conditions in order to improve grid stability. The disclosure is further related to a corresponding controller.
Background Such a method is shown e.g. in EP1855367. By being able to cope with voltage fluctuations in the grid and supplying reactive power to the grid, the power generation system can improve the overall stability of the grid. One problem associated with such control method is how to avoid situations where the voltage collapses such that the generation system must be disconnected.
Summary
One object of the present disclosure is therefore to provide a control method of the initially metioned kind with improved stability. This object is achieved by means of a method as defined in claim 1. More specifically the method involves determining a Q-V characteristic for the grid at the point of connection, and controlling the feeding of reactive power based on the Q-V characteristic. In this way it can be avoided that the controller drives the reactive current to a point where the voltage collapses as a result thereof. This improves the stability of the system. The method may further involve determining a nose point for the Q-V characteristic and determining a minimum reactive current, lomin, which is safe from the nose point. The controlling of the feeding of reactive power may then include keeping the reactive current higher than the minimum reactive current. This provides improved reliability, and the minimum reactive currents percentage of the nose point current may be set by a user. The Q-V characteristic may be determined by injecting a disturbance at the point of connection. This means that the Q-V characteristic can be determined at regular intervals, as there is no need to await a disturbance in the grid. The feeding of reactive power to the grid may be controlled by controlling rotor currents of a double fed induction generator, DFIG, or, alternatively by controlling switches of an AC/DC/AC converter configuration connecting a generator with the grid. A controller carrying out the method may be readily integrated in the control loops of any such system, since means for controlling the reactive power is already provided for therein.
The method may be used both in transient and steady state conditions, in order to improve grid stability. A controller comprising functional blocks capable of carrying out the actions of the method implies corresponding advantages and may be varied correspondingly. Such a controller may be included in a wind power generation system.
Brief description of the drawings
Fig 1 illustrates a wind power generating system connected to a grid.
Fig 2 illustrates a Q-V characteristic. Fig 3 illustrates a flow chart for a control method.
Fig 4 shows a configuration of a wind power generation system with a doubly fed induction generator.
Fig 5 shows a configuration of a wind power generation system with a full converter. Fig 6 illustrates schematically a wind power generation system controller.
Detailed description
Fig 1 illustrates a wind power generating facility 1 connected to a grid 3. Generally, the facility comprises a turbine 5, including a plurality of blades and being mounted on a tower 7 and connected, often via a gearbox, to a generator in the tower. The generator in turn is connected to the grid 3 with a three phase connection (zero connection not shown) at a point of connection 9, often via a switched converter (not shown), and usually via one or more transformers (not shown).
In the illustrated case, the wind power generating facility 1 has only one turbine 5. However, a wind power generating facility 1 in the context of this disclosure may comprise a plurality of turbines, which may each be mounted on a tower. The wind power generating facility 1 may thus be a wind farm. In addition to the illustrated type of wind turbine, also vertical axis turbines are conceivable.
Grid codes established by authorities and grid operators require that wind power generating facilities are capable of staying connected to the grid during a fault in the grid, which capability is known as low voltage ride through, LVRT. Moreover, the power generating facilities should be able to supply reactive power to or absorb reactive power from the grid during a transient condition. For instance, if a voltage dip occurs due to a fault on one or more grid phases, the power generating facility should be able to supply reactive current to the grid in order to improve stability. Reactive power regulating means 11 is therefore connected to the grid 3 at the point of connection. The reactive power regulating means 11 may be integrated with the energy conversion link in the system or may be provided as a separate auxiliary unit. Various ways of regulating reactive power in accordance with the present disclosure will be described later, in connection with figs 4 and 5. In this disclosure, a transient condition refers not only to voltage dips in the grid, but to any sudden change in grid parameters that can be affected by injecting or absorbing reactive power to or from the grid at the point of connection. Thus, for instance a voltage surge is also included.
Fig 2 illustrates a Q-V characteristic 13 for a typical connection point of a grid. In this disclosure Q relates to the amount of reactive power (VAr) injected to or absorbed from the grid by adding or subtracting reactive current at the point of connection to the grid. V relates to the grid voltage at the point of connection. The Q-V characteristic shows the relation between the two parameters. The characteristic is, for higher added reactive currents, relatively linear. See the Q-V characteristics to the right of the voltage V relating to the point Qmm. For these relatively higher currents in the illustrated charcteristics the voltage increases with increasing added reactive current. However, the Q-V curve as a whole has a parabolic nature. Consequently, at a point 15 of the Q-V characteristic dV/dQ is zero. This point is called a nose point 15, and the present charcteristics of the grid determines where the nose point 15 is situated. Below this point, an increase in added reactive current will decrease the voltage instead of increasing it, and such an increase in added reactive current would consequently worsen the state of the grid.
Therefore, the present disclosure provides a control method where the provision of reactive power is controlled so as to be kept at a safe part of the Q-V characteristics, where a certain margin to the nose point is provided. This means that the risk of the wind power generation system worsening the state of the grid is more or less eliminated. Fig 3 illustrates a flow chart for a control method.
Firstly, the Q-V characteristic for the grid at the point of connection is determined 21. For any given active power level, the Q-V-curve in the desired operating range resembles a parabolic function with the form:
aQ=V2+bV+c
By injecting a disturbance, typically by increasing the injected reactive current, the parameters a, b, and c can be determined. It is however also possible to utilise other disturbances in the system, e.g. a voltage drop to determine the characteristic.
The nose point for the Q-V characteristic is determined 23. This can be done simply by finding the point on the characteristic where dQ/dV is zero which is a very simple operation.
Then, thirdly, a minimum reactive current, lQmm, is determined 25. This current should be safe from the nose point, i.e. in some distance from and above the nose point, typically meaning that lQmm is 110% of the current that corresponds to the nose point. However, this percentage is only an example and may be varied in accordance with grid stability requirements or operator settings. Hereby, the operation is kept at points of the Q-V characteristic at reactive currents IQ greater than the minimum reactive current lQmm so that the voltage V is kept higher than the voltage corresponding to the nose point. Hereby, it is ensured that an increase in added reactive current will increase the voltage. Then the controller is set 27 to provide lQmm as a minimum reactive current, such that the added reactive current is kept higher than the level providing the minimum reactive current even during a LVRT condition.
A reactive power regulating means 11 (cf. Fig 1) should comprise functional blocks for carrying out these actions. Fig 6 illustrates a regulator comprising such blocks, namely a Q-V characteristics detector 51 , a nose point detector 53, an lQmm determination unit 55, and a current controller 57. Such blocks may typically be software implemented as routines executed on a digital signal processor even though various hardware configurations, e.g. utilising applications specific integrated circuits, ASICs, would in principle also be conceivable.
Fig 4 shows a power conversion configuration with a doubly fed induction generator 31 , connected to a wind turbine (not shown). A slip ring may be used to feed currents 33 to windings in the rotor. The rotor currents 33 may be provided by means of an AC/DC/AC converter 35 connected to the generator 31 output. Such doubly fed induction generators allow the rotor of the generator to rotate with a varying rotation speed, out of synchronism with the grid frequency. Optionally, a transformer (not shown) may be placed between the grid 3 and the generator 31. Additionally, as is well known per se, the amount of active and reactive power that is fed to the grid may be controlled by controlling the currents fed to the rotor windings of the generator. In the context of the present disclosure, the regulator 11 may then have the converter 35 as an integrated part, generating the rotor currents that provide the desired amount of added reactive power.
Fig 5 shows a power conversion configuration for a synchronous generator 41 , connected to a wind turbine (not shown). Then, a permanent magnet synchronous generator PMSG 41 is used together with an AC/DC/AC converter configuration 43, 45, 47. The converter configuration comprises an AC/DC converter 43, connected to the stator windings of the generator 41. The AC/DC converter 43 feeds DC power to a filter capacitor 45. A DC/AC converter 47 feeds power from the filter capacitor 45 to the grid 3. The amount of active and reactive power supplied to the grid may be controlled by controlling the switches of the DC/AC converter in the configuration, which forms part of the reactive power regulator 11.
As a further alternative, the reactive power regulator 11 may include a static VAR capacitor bank may be used to control the reactive power produced. In principle, a rotating compensator could also be used in the same way. The present disclosure is not limited to the described embodiments, it may be altered and varied in different ways within the scope of the appended claims.

Claims

1. A method for controϋing a wind power generation system connected to a grid at a point of connection, wherein the system is devised to feed reactive power to the grid, characterised by:
-determining (21) a Q-V characteristic for the grid at the point of connection; and
-controlling (27) the feeding of reactive power based on the Q-V characteristic.
2. A method according to claim 1 , wherein the method further comprises:
-determining (23) a nose point for the Q-V characteristic; and -determining (25) a minimum reactive current, lQmin, which is safe from the nose point; and wherein - the controlling (27) of the feeding of reactive power includes keeping the reactive current higher than the minimum reactive current, lomin-
3. A method according to claim 1 or 2, wherein, the Q-V characteristic is determined by injecting a disturbance at the point of connection.
4. A method according to any of the preceding claims, wherein the feeding of reactive power to the grid is controlled by controlling rotor currents of a double fed induction generator, DFIG.
5. A method according to any of claims 1-3, wherein the feeding of reactive power to the grid is controlled by controlling switches of an AC/DC/AC converter configuration connecting a generator with the grid.
6. A method according to any of the preceding claims, wherein the method is used in transient conditions.
7. A method according to any of claims 1-5, wherein the method is used in steady state conditions.
8. A controller for controlling a wind power generation system connected to a grid at a point of connection, wherein the system is devised to feed reactive power to the grid, characterised by:
-a Q-V characteristic detector (51) for determining the Q-V characteristic for the grid at the point of connection; and -a controller (57), controlling the feeding of reactive power based on the Q-V characteristic.
9. A controller according to claim 8, wherein the controller further comprises: - a nose point detector (53) for detecting the nose point of the Q-V characteristic; and
-a determination unit (55) determining a minimum reactive current, iQmin, which is safe from the nose point; and wherein
-the controller (57) is devised to keep the reactive current higher than the minimum reactive current, lQmin.
10. A wind power generating system comprising a controller according to any of claims 8 or 9.
PCT/EP2009/066974 2008-12-12 2009-12-11 Control method and apparatus WO2010066892A2 (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN200980156704.5A CN102318157B (en) 2008-12-12 2009-12-11 Control method and apparatus
EP09795963.9A EP2376773B1 (en) 2008-12-12 2009-12-11 Control method and apparatus
ES09795963.9T ES2581427T3 (en) 2008-12-12 2009-12-11 Method and control device

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US12209008P 2008-12-12 2008-12-12
US61/122,090 2008-12-12
DKPA200801776 2008-12-12
DKPA200801776 2008-12-12

Publications (2)

Publication Number Publication Date
WO2010066892A2 true WO2010066892A2 (en) 2010-06-17
WO2010066892A3 WO2010066892A3 (en) 2011-08-18

Family

ID=42239595

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2009/066974 WO2010066892A2 (en) 2008-12-12 2009-12-11 Control method and apparatus

Country Status (5)

Country Link
US (1) US8615331B2 (en)
EP (1) EP2376773B1 (en)
CN (1) CN102318157B (en)
ES (1) ES2581427T3 (en)
WO (1) WO2010066892A2 (en)

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101995529B (en) * 2009-08-21 2015-01-28 维斯塔斯风力系统集团公司 System and method for monitoring power filters and detecting power filter failure in wind turbine electrical generator
US8970057B2 (en) * 2010-03-31 2015-03-03 Vestas Wind Systems A/S Method of operating a wind turbine, wind turbine, wind turbine controlling system, and processing system
TWI449838B (en) * 2010-12-07 2014-08-21 Univ Nat Cheng Kung System and method of integrating wind power and tide energy
US8121739B2 (en) * 2010-12-29 2012-02-21 Vestas Wind Systems A/S Reactive power management for wind power plant internal grid
US10103661B2 (en) 2011-09-28 2018-10-16 Vestas Wind Systems A/S Wind power plant and a method for operating thereof
WO2013071098A1 (en) * 2011-11-11 2013-05-16 Power Quality Renaissance, Llc Reactive following for distributed generation and loads of other reactive controller(s)
DK2629386T3 (en) * 2012-02-16 2018-04-16 Ge Renewable Tech PROCEDURE TO AVOID VOLTAGE INSTABILITY IN A OFFSHORE WINDOW PARK PARK
DE102012212364A1 (en) 2012-07-13 2014-01-16 Wobben Properties Gmbh Method and device for feeding electrical energy into an electrical supply network
US9244506B2 (en) * 2012-11-16 2016-01-26 Siemens Aktiengesellschaft Method of controlling a power plant
JP5766364B1 (en) * 2013-08-15 2015-08-19 三菱電機株式会社 Voltage monitoring control device and voltage control device
US10042374B2 (en) 2014-06-13 2018-08-07 Siemens Gamesa Renewable Energy A/S Method and apparatus for determining a weakened grid condition and controlling a power plant in a manner appropriate to the grid condition
US20170317630A1 (en) * 2016-04-29 2017-11-02 Hamilton Sundstrand Corporation PMG Based Variable Speed Constant Frequency Generating System
CN113726136B (en) * 2020-05-26 2023-11-03 台达电子企业管理（上海）有限公司 conversion device
CN113726137B (en) * 2020-05-26 2023-11-03 台达电子企业管理（上海）有限公司 conversion device
US11509138B1 (en) * 2020-05-27 2022-11-22 Mohd Hasan Ali System and method for improving transient stability of grid-connected wind generator system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5745368A (en) * 1996-03-29 1998-04-28 Siemens Energy & Automation, Inc. Method for voltage stability analysis of power systems
US5796628A (en) * 1995-04-20 1998-08-18 Cornell Research Foundation, Inc. Dynamic method for preventing voltage collapse in electrical power systems
US20070216164A1 (en) * 2006-03-17 2007-09-20 Ingeteam, S.A. Of Pamplona Variable speed wind turbine having an exciter machine and a power converter not connected to the grid
EP1855367A1 (en) * 2005-02-23 2007-11-14 Gamesa Innovation & Technology, S.L. Method and device for injecting reactive current during a mains supply voltage dip

Family Cites Families (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6670721B2 (en) * 2001-07-10 2003-12-30 Abb Ab System, method, rotating machine and computer program product for enhancing electric power produced by renewable facilities
PL199777B1 (en) 2001-12-24 2008-10-31 B Spo & Lstrok Ka Z Ograniczon Method of identifying weak and/or strong branches of a power distribution system
US7015595B2 (en) * 2002-02-11 2006-03-21 Vestas Wind Systems A/S Variable speed wind turbine having a passive grid side rectifier with scalar power control and dependent pitch control
US7087332B2 (en) * 2002-07-31 2006-08-08 Sustainable Energy Systems, Inc. Power slope targeting for DC generators
WO2004098261A2 (en) * 2003-05-02 2004-11-18 Xantrex Technology Inc. Control system for doubly fed induction generator
WO2005002022A1 (en) 2003-06-27 2005-01-06 Robert Schlueter Voltage collapse diagnostic and atc system
DE10357292B4 (en) * 2003-12-05 2006-02-02 Voith Turbo Gmbh & Co. Kg A method of controlling a powertrain for a speed-controlled turbofan engine, power shock reduction, and short-term energy storage
US8436490B2 (en) * 2005-08-30 2013-05-07 Abb Research Ltd. Wind mill power flow control with dump load and power converter
US7680562B2 (en) * 2005-09-08 2010-03-16 General Electric Company Power generation system
US7391126B2 (en) * 2006-06-30 2008-06-24 General Electric Company Systems and methods for an integrated electrical sub-system powered by wind energy
DE102006054870A1 (en) * 2006-11-20 2008-06-12 Repower Systems Ag Wind turbine with negative sequence control and operating procedure
WO2008131777A2 (en) * 2007-04-30 2008-11-06 Vestas Wind Systems A/S Variable speed wind turbine with doubly-fed induction generator compensated for varying rotor speed
US8198742B2 (en) * 2007-12-28 2012-06-12 Vestas Wind Systems A/S Variable speed wind turbine with a doubly-fed induction generator and rotor and grid inverters that use scalar controls
ES2430046T3 (en) * 2007-12-28 2013-11-18 Vestas Wind Systems A/S Apparatus and procedure for operating a wind turbine under conditions of low supply network voltage
US20110019443A1 (en) * 2008-02-15 2011-01-27 Wind To Power System, S.L. Series voltage compensator and method for series voltage compensation in electrical generators
DE102008017715A1 (en) * 2008-04-02 2009-10-15 Nordex Energy Gmbh Method for operating a wind turbine with a double-fed asynchronous machine and wind turbine with a double-fed asynchronous machine
US8120932B2 (en) * 2008-07-01 2012-02-21 American Superconductor Corporation Low voltage ride through
DE102008039429A1 (en) * 2008-08-23 2010-02-25 DeWind, Inc. (n.d.Ges.d. Staates Nevada), Irvine Method for controlling a wind farm
US8610306B2 (en) * 2011-07-29 2013-12-17 General Electric Company Power plant control system and method for influencing high voltage characteristics

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5796628A (en) * 1995-04-20 1998-08-18 Cornell Research Foundation, Inc. Dynamic method for preventing voltage collapse in electrical power systems
US5745368A (en) * 1996-03-29 1998-04-28 Siemens Energy & Automation, Inc. Method for voltage stability analysis of power systems
EP1855367A1 (en) * 2005-02-23 2007-11-14 Gamesa Innovation & Technology, S.L. Method and device for injecting reactive current during a mains supply voltage dip
US20070216164A1 (en) * 2006-03-17 2007-09-20 Ingeteam, S.A. Of Pamplona Variable speed wind turbine having an exciter machine and a power converter not connected to the grid

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
ALMEIDA R G ET AL: "Influence of the Variable-Speed Wind Generators in Transient Stability Margin of the Conventional Generators Integrated in Electrical Grids", IEEE TRANSACTIONS ON ENERGY CONVERSION, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 19, no. 4, 1 December 2004 (2004-12-01), pages 692-701, XP011122239, ISSN: 0885-8969, DOI: DOI:10.1109/TEC.2004.832078 *
BREKKEN T K A ET AL: "Control of a Doubly Fed Induction Wind Generator Under Unbalanced Grid Voltage Conditions", IEEE TRANSACTIONS ON ENERGY CONVERSION, IEEE SERVICE CENTER, PISCATAWAY, NJ, US, vol. 22, no. 1, 1 March 2007 (2007-03-01), pages 129-135, XP011184062, ISSN: 0885-8969, DOI: DOI:10.1109/TEC.2006.889550 *
GOVINDA RAO G ET AL: "Model Validation Studies in Obtaining Q-V Characteristics of P-Q Loads in Respect of Reactive Power Management and Voltage Stability", POWER ELECTRONICS, DRIVES AND ENERGY SYSTEMS, 2006 INTERNATIONAL CONFE RENCE ON, IEEE, PI, 1 December 2006 (2006-12-01), pages 1-5, XP031073083, ISBN: 978-0-7803-9771-2 *
LING PENG ET AL: "Modeling and control of doubly fed induction generator wind turbines by using Causal Ordering Graph during voltage dips", ELECTRICAL MACHINES AND SYSTEMS, 2008. ICEMS 2008. INTERNATIONAL CONFERENCE ON, IEEE, PISCATAWAY, NJ, USA, 17 October 2008 (2008-10-17), pages 2412-2417, XP031416155, ISBN: 978-1-4244-3826-6 *
MOHAMED M B ET AL: "Doubly fed induction generator (DFIG) in wind turbine. modeling and power flow control", INDUSTRIAL TECHNOLOGY, 2004. IEEE ICIT '04. 2004 IEEE INTERNATIONAL CO NFERENCE ON HAMMAMET, TUNSIA DEC. 8-10, 2004, PISCATAWAY, NJ, USA,IEEE, vol. 2, 8 December 2004 (2004-12-08), pages 580-584, XP010819741, DOI: DOI:10.1109/ICIT.2004.1490139 ISBN: 978-0-7803-8662-4 *

Also Published As

Publication number Publication date
US20100148508A1 (en) 2010-06-17
CN102318157A (en) 2012-01-11
WO2010066892A3 (en) 2011-08-18
EP2376773B1 (en) 2016-06-15
US8615331B2 (en) 2013-12-24
EP2376773A2 (en) 2011-10-19
CN102318157B (en) 2014-07-23
ES2581427T3 (en) 2016-09-05

Similar Documents

Publication Publication Date Title
US8615331B2 (en) Method and apparatus for controlling the feed of reactive power in a wind power generation system
Geng et al. Synchronization and reactive current support of PMSG-based wind farm during severe grid fault
Howlader et al. A comprehensive review of low voltage ride through capability strategies for the wind energy conversion systems
Chen et al. A review of the state of the art of power electronics for wind turbines
US9478987B2 (en) Power oscillation damping employing a full or partial conversion wind turbine
US8198742B2 (en) Variable speed wind turbine with a doubly-fed induction generator and rotor and grid inverters that use scalar controls
EP2688172B1 (en) Method and apparatus for adaptively controlling wind park turbines
CN108683198A (en) The voltage-controlled type virtual synchronous method of double-fed wind power generator group
EP3464889B1 (en) Operating a wind turbine generator during an abnormal grid event
Kynev et al. Comparison of modern STATCOM and synchronous condenser for power transmission systems
CN110380449A (en) Monopole is latched wind power direct current transmitting system control method for coordinating under failure
CN115681000A (en) Method for power control based on inverter resources with grid forming converter
Kim et al. Hierarchical Voltage Control of a Wind Power Plant Using the Adaptive I Q-V Characteristic of a Doubly-Fed Induction Generator
Montazeri et al. Improved low voltage ride thorough capability of wind farm using STATCOM
Chen Characteristics of induction generators and power system stability
Heng et al. Improved control strategy of an active crowbar for directly-driven PM wind generation system under grid voltage dips
Jun et al. An improved control strategy for double feed induction generator in low frequency resonant power grid
Hu et al. A novel control strategy for Doubly Fed Induction Generator and Permanent Magnet Synchronous Generator during voltage dips
Dey et al. Comparison of synchronous and stationary frame pi based flux weakening controls for DC-link overvoltage minimisation of WECS under grid fault
Apata Reactive power compensation of fixed speed wind turbines using a hybrid wind turbine technology
Liao et al. Unbalanced-grid-fault ride-through control for a doubly fed induction generator wind turbine with series grid-side converter
Ge et al. Active support control strategy of permanent magnet synchronous wind turbine and its adaptability analysis under weak grid
Simon et al. Transient modeling and control of dfig with fault ride through capability
Das et al. Protection and voltage control of DFIG wind turbines during grid faults
Masaud Modeling, analysis, control and design application guidelines of doubly fed induction generator (DFIG) for wind power applications

Legal Events

Date Code Title Description
WWE Wipo information: entry into national phase

Ref document number: 200980156704.5

Country of ref document: CN

121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 09795963

Country of ref document: EP

Kind code of ref document: A2

NENP Non-entry into the national phase

Ref country code: DE

WWE Wipo information: entry into national phase

Ref document number: 4931/CHENP/2011

Country of ref document: IN

WWE Wipo information: entry into national phase

Ref document number: 2009795963

Country of ref document: EP