Wind turbine and a method of operating thereof

• US 9,347,434 B2
• Filed: 12/21/2012
• Issued: 05/24/2016
• Est. Priority Date: 12/29/2011
• Status: Active Grant

• Current Assignee: Vestas Wind Systems A/S
• Original Assignee: Vestas Wind Systems A/S
• Inventors: Gupta, Amit Kumar, Thia, Hock Heng, Doan, Duy Duc, Andersen, Gert Karmisholt
• Primary Examiner(s): Patel, Tulsidas C
• Assistant Examiner(s): NGUYEN, VIET P
• Application Number:
  US14/362,052
• Publication Number:
  US 20140312622A1
• Time in Patent Office: 1,250 Days
• US Class Current: 1/1
• CPC Class Codes: F03D 7/0264 for stopping; controlling in emergency situations orientating out of wind F03D7/0208
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: H02P 9/08 Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation
• 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

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.

Claims

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.