METHOD OF CONTROLLING A WIND TURBINE CONNECTED TO AN ELECTRIC UTILITY GRID

• US 20090079193A1
• Filed: 12/28/2004
• Published: 03/26/2009
• Est. Priority Date: 12/28/2004
• Status: Active Grant

• Current Assignee: Vestas Wind Systems A/S
• Original Assignee: Vestas Wind Systems A/S
• Inventors: Esbensen, Claus, Nielsen, John Godsk
• Granted Patent: US 7,859,125 B2
• Time in Patent Office: Days
• US Class Current: 290/44
• CPC Class Codes: F03D 7/0272 by measures acting on the electrical generator
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: F05B 2270/107 to cope with emergencies
• CPC Class Codes: H02M 1/0096 Means for increasing hold-up time, i.e. the duration of time that a converter's output will remain within regulated limits following a loss of input power
• CPC Class Codes: H02M 5/458 using semiconductor devices only
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/105 for increasing the stability
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y02E 10/76 Power conversion electric or electronic aspects

Abstract

The invention relates to a method of controlling a wind turbine connected to an electric utility grid during malfunction in said electric utility grid (9). The method comprises the steps of detecting a malfunction in said electric utility grid and operating at least two control units of said power converter (12) in relation to at least one power converter limit value. The invention also relates to a control system for a wind turbine connected to a utility grid and a wind turbine.

Claims

1. Method of controlling a wind turbine, including an electric generator and a power converter, connected to an electric utility grid during a malfunction in said grid, said method comprising

detecting the malfunction in said electric utility grid, and

operating at least two control units of said power converter in relation to at least one power converter limit value and at least one further value.

2. Method of controlling a wind turbine according to claim 1 where said at least two control units are operated in relation to a minimum or a maximum limit voltage value of a DC link in said power converter in order to keep the voltage value of the DC link in between said minimum and maximum limit voltage values.

3. Method of controlling a wind turbine according to claim 2 where said control units include generator and grid side circuits of the power converter which are operated to disconnect said power converter from the electric generator and the electric utility grid at the reach of said minimum or maximum limit value of the DC link.

4. Method of controlling a wind turbine according to claim 2 where said control units further comprise one or more resistor blocks which connects at least one resistor between busbars of the DC link in said power converter.

5. Method of controlling a wind turbine according to claim 4 where said at least one resistor is switchable connected to the busbars.

6. Method of controlling a wind turbine according to claim 4 where each of said resistor blocks is switched with a frequency depending on the voltage value of the DC link.

7. Method of controlling a wind turbine according to claim 4 where said resistor blocks are successively becoming active as the voltage value of the DC link moves up.

8. Method of controlling a wind turbine according to claim 4 where each of said resistor blocks is active in limited time periods.

9. Method of controlling a wind turbine according to claim 4 where each of said resistor blocks is operated and becoming active in relation to a block temperature.

10. Control system for controlling a wind turbine connected to an electric utility grid during a malfunction in said grid, said system comprising

means for detecting the malfunction in said electric utility grid,

a power converter, and

at least two control units of said power converter controlled in relation to at least one power converter limit value during said malfunction and at least one further value.

11. Control system according to claim 10

wherein said at least two units comprise a plurality of resistor blocks wherein each block includes at least one resistor and switch.

12. Control system according to claim 11

wherein said resistor blocks further include temperature measuring means.

13. Control system according to claim 10

wherein said at least two units also include generator and grid side circuits of the power converter mutually connected by a DC link of the power converter.

14. Control system according to claim 13

wherein said system includes means for measuring the DC link voltage value and means for comparing said value with limit values.

15. Wind turbine connected to a utility grid comprising

an electric generators

a power converters connected to said electric generator and utility grid, and

a control system according to claims 10.

16. Wind turbine according to claim 15 wherein said at least two units of said power converter are positioned in a distance from each other.