Method and systems for operating a wind turbine using dynamic braking in response to a grid event

• US 8,664,788 B1
• Filed: 09/07/2012
• Issued: 03/04/2014
• Est. Priority Date: 09/07/2012
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Wagoner, Robert Gregory, Ritter, Allen Michael, Larsen, Einar Vaughn, Klodowski, Anthony Michael, Barker, Sidney Allen
• Primary Examiner(s): Cuevas, Pedro J
• Application Number:
  US13/606,530
• Publication Number:
  US 20140070535A1
• Time in Patent Office: 543 Days
• Field of Search: 290/44, 290/55
• US Class Current: 290/44
• CPC Class Codes: F03D 7/0244 for braking
• CPC Class Codes: F05B 2260/90 Braking
• CPC Class Codes: F05B 2270/107 to cope with emergencies
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/381 Dispersed generators
• 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 method and system for dissipating energy in a direct current (dc) bus of a doubly-fed induction generator (DFIG) converter during a grid event is described. In one aspect, the method comprises monitoring operating conditions of an electrical system, the electrical system comprising at least a DFIG generator and a line side converter and a rotor side converter connected by a dc bus having a dynamic brake connected thereto; detecting an overvoltage on the dc bus or a condition indicative of an overvoltage on the dc link is detected, the overvoltage on the dc bus or condition indicative of the overvoltage caused by a grid event; and causing energy in the dc link to be dissipated using the dynamic brake.

Claims

1. A method of dissipating energy in a direct current (dc) bus of a doubly-fed induction generator (DFIG) converter during a grid event, said method comprising:

monitoring, by a controller, operating conditions of an electrical system, said electrical system comprising at least a DFIG generator and a line side converter and a rotor side converter connected by a dc bus having a dynamic brake connected thereto;

detecting, by the controller, an overvoltage on the dc bus or a condition indicative of an overvoltage on the dc link is detected, said overvoltage on the dc bus or condition indicative of the overvoltage caused by a grid event; and

causing, by the controller, energy in the dc link to be dissipated using the dynamic brake.

2. The method of claim 1, wherein monitoring, by the controller, operating conditions of the electrical system comprises monitoring voltage on the dc link.

3. The method of claim 1, wherein monitoring, by the controller, operating conditions of the electrical system comprises monitoring alternating current (AC) voltage or current on at least a portion of an electrical grid connected to the DFIG generator the line side converter.

4. The method of claim 1, wherein detecting, by the controller, a condition indicative of an overvoltage on the dc link comprises detecting a high alternating current (AC) voltage or current on at least a portion of an electrical grid connected to the DFIG generator the line side converter.

5. The method of claim 1, wherein causing, by the controller, energy in the dc link to be dissipated using the dynamic brake comprises determining that the monitored voltage on the dc link reaches or exceeds a threshold and causing a switch of the dynamic brake to allow current to pass through the switch and energy be at least partially dissipated by a resistor of the dynamic brake.

6. The method of claim 1, wherein causing, by the controller, energy in the dc link to be dissipated using the dynamic brake comprises monitoring alternating current (AC) voltage or current on at least a portion of an electrical grid connected to the DFIG generator and the line side converter and timing operation of a switch in the dynamic brake such that oscillations between the portion of the electrical grid and the dc link are reduced.

7. The method of claim 1, wherein detecting, by the controller, the overvoltage on the dc bus or condition indicative of the overvoltage caused by a grid event comprises detecting the overvoltage on the dc bus or condition indicative of the overvoltage caused by islanding.

8. A method of dissipating energy in a direct current (dc) bus of a doubly-fed induction generator (DFIG) converter during an islanding event, said method comprising:

detecting, by a controller, an indicator of islanding of a DFIG generator and a DFIG converter, said DFIG converter comprising a line side converter and a rotor side converter connected by a dc bus having a dynamic brake connected thereto, said DFIG generator and line side converter connected to at least a portion of an electrical grid subsequent to the islanding; and

causing, by the controller, energy in the dc bus of the DFIG converter to be dissipated based on the detected indicator of islanding condition, said energy dissipated using the dynamic brake.

9. The method of claim 8, wherein detecting, by the controller, the indicator of islanding of a DFIG generator and a DFIG converter comprises detecting the indicator of islanding by one or more of grid frequency deviation, grid voltage deviation, measured torque not following commanded torque for a predetermined time, turbine overspeed, tower vibration, or receiving a signal from an external device indicating status of grid connections.

10. The method of claim 8, wherein causing, by the controller, energy in the dc link to be dissipated using the dynamic brake comprises determining that a monitored voltage on the dc link reaches or exceeds a threshold and causing a switch of the dynamic brake to allow current to pass through the switch and energy be at least partially dissipated by a resistor of the dynamic brake.

11. The method of claim 8, wherein causing, by the controller, energy in the dc link to be dissipated using the dynamic brake comprises monitoring alternating current (AC) voltage or current on the portion of the electrical grid connected to the DFIG generator and the line side converter and timing operation of a switch in the dynamic brake such that oscillations between the portion of the electrical grid and the dc link are reduced.

12. A system for dissipating energy in a direct current (dc) bus of a doubly-fed induction generator (DFIG) converter connected to a wind turbine during a grid event, the system comprising:

a DFIG generator coupled to a utility grid via a dual path, said dual path defined by a stator bus and a rotor bus;

a DFIG converter coupled to said generator via a rotor bus and coupled to the utility grid via a line bus, said DFIG converter comprising a line side converter and a rotor side converter connected by a dc bus having a dynamic brake connected thereto; and

a controller, wherein the controller is configured to receive and transmit signals to and from an electrical system comprising at least the utility grid, DFIG generator and the DFIG converter, said controller further configured to;

monitor operating conditions of the utility grid, DFIG generator, line side converter, rotor side converter, dc bus and dynamic brake;

detect an overvoltage on the dc bus or a condition indicative of an overvoltage on the dc link, said overvoltage on the dc bus or condition indicative of the overvoltage caused by a grid event; and

cause energy in the dc link to be dissipated using the dynamic brake.

13. The system of claim 12, wherein monitoring, by the controller, operating conditions of the electrical system comprises monitoring voltage on the dc link.

14. The system of claim 12, wherein monitoring, by the controller, operating conditions of the electrical system comprises monitoring alternating current (AC) voltage or current on at least a portion of the utility grid connected to the DFIG generator and the line side converter.

15. The system of claim 12, wherein detecting, by the controller, a condition indicative of an overvoltage on the dc link comprises detecting a high alternating current (AC) voltage or current on at least a portion of the utility grid connected to the DFIG generator and the line side converter.

16. The system of claim 12, wherein causing, by the controller, energy in the dc link to be dissipated using the dynamic brake comprises determining that the monitored voltage on the dc link reaches or exceeds a threshold and causing a switch of the dynamic brake to allow current to pass through the switch and energy be at least partially dissipated by a resistor of the dynamic brake.

17. The system of claim 12, wherein causing, by the controller, energy in the dc link to be dissipated using the dynamic brake comprises monitoring alternating current (AC) voltage or current on at least a portion of the utility grid connected to the DFIG generator and the line side converter and timing operation of a switch in the dynamic brake such that oscillations between the portion of the utility grid and the dc link are reduced.

18. The system of claim 12, wherein detecting, by the controller, the overvoltage on the dc bus or condition indicative of the overvoltage caused by a grid event comprises detecting the overvoltage on the dc bus or condition indicative of the overvoltage caused by islanding.

19. The system of claim 12, wherein the controller is further configured to detect islanding of the DFIG generator and the DFIG converter and cause energy in the dc bus of the DFIG converter to be dissipated based on the detected islanding condition, said energy dissipated using the dynamic brake, wherein detecting, by the controller, islanding of a DFIG generator and a DFIG converter comprises detecting islanding by one or more of grid frequency deviation, grid voltage deviation, measured torque not following commanded torque for a predetermined time, turbine overspeed, tower vibration, or receiving a signal from an external device indicating status of grid connections.

20. The system of claim 12, wherein dissipating energy using the dynamic brake allows the usable speed range of the wind turbine to be expanded and dissipating energy using the dynamic brake aids in the response time of the wind turbine'"'"'s pitch control system.