Methods for operating electrical power systems

• US 10,186,996 B1
• Filed: 09/15/2017
• Issued: 01/22/2019
• Est. Priority Date: 09/15/2017
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Holliday, Cornelius Edward, Smith, David
• Primary Examiner(s): Cuevas, Pedro J
• Application Number:
  US15/705,685
• Time in Patent Office: 494 Days
• Field of Search: 322 87, 290 52
• CPC Class Codes: F03D 7/00 Controlling wind motors supplying or distributing electrical power H02J, e.g. arrangements for adjusting, eliminating or compensating reactive power in networks H02J3/18; controlling electric generators H02P, e.g. arrangements for controlling electric generators for the purpose of obtaining a desired output H02P9/00
• CPC Class Codes: F03D 7/0272 by measures acting on the electrical generator
• CPC Class Codes: F05B 2260/903 using electrical or magnetic forces
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 29/0241 the fault being an overvoltage
• CPC Class Codes: H02P 9/006 Means for protecting the generator by using control H02H7/06 takes precedence; control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10
• CPC Class Codes: H02P 9/007 Control circuits for doubly fed generators
• CPC Class Codes: H02P 9/102 for limiting effects of transients
• CPC Class Codes: H02P 9/107 for limiting effects of overloads
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

A method for operating an electrical power system includes disabling bridge switching of one of the rotor-side converter or line-side converter. The method further includes gating on the dynamic brake after the disabling occurs, comparing a power converter input variable to a primary predetermined variable threshold, and forcing the gated-on dynamic brake to a 100 percent duty cycle when the power converter input variable exceeds the primary predetermined variable threshold.

Claims

1. A method for operating an electrical power system, the method comprising:

disabling bridge switching of one of the rotor-side converter or line-side converter;

gating on the dynamic brake after the disabling occurs;

comparing a power converter input variable to a primary predetermined variable threshold; and

forcing the gated-on dynamic brake to a 100 percent duty cycle when the power converter input variable exceeds the primary predetermined variable threshold.

2. The method of claim 1, further comprising:

comparing, after forcing occurs, the power converter input variable to a secondary predetermined variable threshold; and

terminating the forced 100 percent duty cycle of the gated-on dynamic brake when the power converter input variable is less than the secondary predetermined variable threshold.

3. The method of claim 1, wherein the secondary predetermined variable threshold is different from the primary predetermined variable threshold.

4. The method of claim 1, wherein the power converter input variable comprises one or more of a DC link voltage, a DC link energy, a DC link current, a rotor-side converter bridge current magnitude, a rotor-side converter bridge voltage magnitude, a rotor-side converter bridge instantaneous current, a rotor-side converter bridge instantaneous voltage, a line-side converter bridge current magnitude, a line-side converter bridge voltage magnitude, a line-side converter bridge instantaneous current, a line-side converter bridge instantaneous voltage, or a power converter component temperature.

5. The method of claim 1, further comprising:

comparing one of a DC link voltage or a DC link energy to a primary predetermined crowbar threshold; and

activating a crowbar when the one of the DC link voltage or a DC link energy exceeds the primary predetermined crowbar threshold.

6. The method of claim 5, wherein the crowbar comprises switching elements of the rotor-side converter.

7. The method of claim 5, wherein the crowbar comprises switching elements disposed upstream of the rotor-side converter within the power converter.

8. The method of claim 1, wherein the one of the rotor-side converter or line-side converter is a plurality of rotor-side converters connected in parallel or a plurality of line-side converters connected in parallel.

9. The method of claim 1, further comprising:

detecting a bridge current magnitude in a rotor-side converter or line-side converter of a power converter, the power converter electrically coupled between a generator rotor and a transformer and comprising a DC link and a dynamic brake; and

comparing the bridge current magnitude in the one of the rotor-side converter or line-side converter to a primary predetermined magnitude threshold,

wherein disabling occurs when the bridge current magnitude exceeds the primary predetermined magnitude threshold.

10. The method of claim 9, further comprising:

comparing, after disabling occurs, the bridge current magnitude in the one of the rotor-side converter or line-side converter to a secondary predetermined threshold; and

enabling bridge switching of the one of the rotor-side converter or line-side converter when the bridge current magnitude is less than the secondary predetermined threshold.

11. An electrical power system, comprising:

a doubly fed induction generator having a rotor and a stator, the stator providing AC power to a stator bus;

a power converter coupled to the rotor of the doubly fed induction generator, the power converter providing an output to a line bus, the power converter comprising a rotor-side converter, a line-side converter, a DC link and a dynamic brake;

a transformer coupled to the stator bus and the line bus; and

a controller communicatively coupled to the power converter, the controller configured to perform one or more operations, the one or more operations comprising;

disabling bridge switching of one of the rotor-side converter or line-side converter;

gating on the dynamic brake after the disabling occurs;

comparing a power converter input variable to a primary predetermined variable threshold; and

forcing the gated-on dynamic brake to a 100 percent duty cycle when the power converter input variable exceeds the primary predetermined variable threshold.

12. The electrical power system of claim 11, wherein the one or more operations further comprises:

comparing, after forcing occurs, the power converter input variable to a secondary predetermined variable threshold; and

terminating the forced 100 percent duty cycle of the gated-on dynamic brake when the power converter input variable is less than the secondary predetermined variable threshold.

13. The electrical power system of claim 11, wherein the secondary predetermined variable threshold is different from the primary predetermined variable threshold.

14. The electrical power system of claim 11, wherein the power converter input variable comprises one or more of a DC link voltage, a DC link energy, a DC link current, a rotor-side converter bridge current magnitude, a rotor-side converter bridge voltage magnitude, a rotor-side converter bridge instantaneous current, a rotor-side converter bridge instantaneous voltage, a line-side converter bridge current magnitude, a line-side converter bridge voltage magnitude, a line-side converter bridge instantaneous current, a line-side converter bridge instantaneous voltage, or a power converter component temperature.

15. The electrical power system of claim 11, wherein the one or more operations further comprises:

comparing one of a DC link voltage or a DC link energy to a primary predetermined crowbar threshold; and

activating a crowbar when the one of the DC link voltage or a DC link energy exceeds the primary predetermined crowbar threshold.

16. The electrical power system of claim 15, wherein the crowbar comprises switching elements of the rotor-side converter.

17. The electrical power system of claim 15, wherein the crowbar comprises switching elements disposed upstream of the rotor-side converter within the power converter.

18. The electrical power system of claim 11, wherein the one of the rotor-side converter or line-side converter is a plurality of rotor-side converters connected in parallel or a plurality of line-side converters connected in parallel.

19. The electrical power system of claim 11, wherein the one or more operations further comprises:

detecting a bridge current magnitude in the rotor-side converter or line-side converter; and

comparing the bridge current magnitude in the one of the rotor-side converter or line-side converter to a primary predetermined magnitude threshold,

wherein disabling occurs when the bridge current magnitude exceeds the primary predetermined magnitude threshold.

20. The electrical power system of claim 19, wherein the one or more operations further comprises:

comparing, after disabling occurs, the bridge current magnitude in the one of the rotor-side converter or line-side converter to a secondary predetermined threshold; and

enabling bridge switching of the one of the rotor-side converter or line-side converter when the bridge current magnitude is less than the secondary predetermined threshold.