Wind turbine and a method of operating thereof

Patent metadata

Field	Value
Publication number	US-9347434-B2
Application number	US-201214362052-A
Country	US
Kind code	B2
Filing date	Dec 21, 2012
Priority date	Dec 29, 2011
Publication date	May 24, 2016
Grant date	May 24, 2016

Abstract

A wind turbine is provided. The wind turbine comprises a generator, a power converter for converting at least a portion of electrical power generated by the generator, an energy dissipating unit and a controller. The power converter comprises a generator-side converter, a grid-side converter and a DC (direct current) link there between. The energy dissipating unit is operatively coupled to the DC-link. The controller is adapted to activate the energy dissipating unit to dissipate energy from the DC-link in response to a shutdown request.

First claim

The invention claimed is:

1. A wind turbine comprising:
a generator;
a first power converter for converting at least a portion of electrical power generated by the generator, the first power converter comprising a generator-side converter, a grid-side converter, and first direct current link (DC-link) disposed therebetween;
an energy dissipating unit operatively coupled to the DC-link; and
a controller configured to, upon determining to shut down the wind turbine:
(a) reduce, prior to activating the energy dissipating unit, a DC-link voltage to a first predetermined voltage value,
(b) stop operation of the grid-side converter when the DC-link voltage is reduced to the predetermined voltage value,
(c) open a circuit breaker to thereby disconnect the wind turbine from an operatively coupled power grid, and
(d) activate the energy dissipating unit to dissipate energy from the DC-link, wherein activating the energy dissipating unit to dissipate energy from the DC-link comprises reducing the DC-link voltage to a second predetermined voltage value for safely performing maintenance on the wind turbine.

2. The wind turbine according to claim 1 , wherein the energy dissipating unit comprises a switch and at least one resistor, wherein the energy dissipating unit is activated by closing the switch.

3. The wind turbine according to claim 2 , wherein the energy dissipating unit comprises a bank of resistors.

4. The wind turbine of claim 2 , wherein the controller is further configured to operate the switch using a signal having a predetermined duty cycle.

5. The wind turbine of claim 1 , wherein determining to shut down the wind turbine comprises one of receiving a request to shut down the wind turbine, detecting a fault of a component of the wind turbine, and detecting a fault of the power grid.

6. The wind turbine of claim 1 , further comprising at least a second power converter coupled with the generator in parallel with the first power converter and including a second DC-link connected with the first DC-link.

7. The wind turbine of claim 1 , wherein the controller is further configured to:
deactivate the energy dissipating unit after dissipating a predetermined amount of energy from the DC-link.

8. The wind turbine of claim 1 , wherein the controller is further configured to complete steps (a) through (d) in less than one second.

9. The wind turbine of claim 1 , wherein the first predetermined voltage value of the DC-link is based on a line voltage at the output of the grid-side converter.

10. The wind turbine of claim 9 , wherein the first predetermined voltage value of the DC-link is further based on a predetermined coefficient, wherein the first predetermined voltage value of the DC-link is controlled according to:
V pre =k× √{square root over (2)}× V Line ,

where V pre represents the first predetermined voltage value, k represents the predetermined coefficient, and V Line represents the line voltage.

11. The wind turbine of claim 10 , wherein a value of the predetermined coefficient is selected between 1.00 and 1.05.

12. A method of operating a wind turbine operatively coupled with a power grid through a circuit breaker, the wind turbine comprising a first power converter for converting at least a portion of electrical power generated by a generator, and further comprising an energy dissipating unit operatively coupled to direct current link (DC-link) of the first power converter, the method comprising:
(a) reducing upon determining to shut down the wind turbine and prior to activating the energy dissipating unit, a DC-link voltage to a first predetermined voltage value;
(b) stopping operation of a grid-side converter of the first power converter when the DC-link voltage is reduced to the first predetermined voltage value;
(c) opening the circuit breaker to thereby disconnect the wind turbine from the power grid; and
(d) activating the energy dissipating unit to dissipate energy from the DC-link, wherein activating the energy dissipating unit to dissipate energy from the DC-link comprises reducing the DC-link voltage to a second predetermined voltage value for safely performing maintenance on the wind turbine.

13. The method of claim 12 , wherein the energy dissipating unit comprises a switch and at least one resistor, wherein the energy dissipating unit is activated by closing the switch.

14. The method of claim 13 , wherein the energy dissipating unit comprises a bank of resistors.

15. The method of claim 12 , wherein determining to shut down the wind turbine comprises one of receiving a request to shut down the wind turbine, detecting a fault of a component of the wind turbine, and detecting a fault of the power grid.

16. The method of claim 12 , further comprising:
deactivating the energy dissipating unit after dissipating a predetermined amount of energy from the DC-link.

17. The method of claim 12 , wherein steps (a) through (d) are completed in less than one second.

18. The method of claim 12 , further comprising:
calculating the first predetermined voltage value of the DC-link based on a line voltage at the output of the grid-side converter, wherein the first predetermined voltage value of the DC-link is calculated according to:
V pre =k× √{square root over (2)}× V Line ,

where V pre represents the first predetermined voltage value, k represents a predetermined coefficient selected between 1.00 and 1.05, and V Line represents the line voltage.

Assignees

• Vestas Wind Sys As

Inventors

• Gupta Amit Kumar
• Thia Hock Heng
• Doan Duy Duc
• Andersen Gert Karmisholt

Classifications

• F03D7/0264 Primary

  for stopping; controlling in emergency situations (orientating out of wind F03D7/0208) · CPC title

• F03D9/255

  connected to electrical distribution networks; Arrangements therefor · CPC title

• H02P29/0241

  the fault being an overvoltage · CPC title

• H02P9/08

  Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation · CPC title

• H02J2101/28

  Wind energy · CPC title