DYNAMIC BRAKING SYSTEM FOR AN ELECTRIC POWER SYSTEM AND METHOD OF OPERATING THE SAME

• US 20150188468A1
• Filed: 07/12/2012
• Published: 07/02/2015
• Est. Priority Date: 07/12/2012
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (General Electric Company)
• Original Assignee: General Electric Company
• Inventors: Xu, Yong, Wagoner, Robert Gregory, Zhu, Jun, Li, Weng, Huang, Jincheng
• Granted Patent: US 9,369,076 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F03D 7/0244 for braking
• 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 9/007 Control circuits for doubly fed generators
• CPC Class Codes: H02P 9/02 Details
• CPC Class Codes: H02P 9/102 for limiting effects of transients
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

A dynamic braking system for an electric power system includes a switching device coupled to an electrical conductor. The switching device is configured to open and close with a plurality of predetermined frequencies. The dynamic braking system also includes an inductive device coupled to the switching device. The power losses of the inductive device are at least partially a function of the plurality of predetermined frequencies. The dynamic braking system further includes a dynamic braking controller coupled to the switching device. The dynamic braking controller is configured to open and close the switching device with at least one of the predetermined frequencies to dissipate electric power from the electrical conductor at a predetermined rate by regulating the power losses of the inductive device as a function of the predetermined frequencies.

Claims

1. A dynamic braking system for an electric power system including at least one electrical conductor, said dynamic braking system comprising:

a switching device coupled to the electrical conductor, said switching device configured to open and close with a plurality of predetermined frequencies;

an inductive device coupled to said switching device, wherein power losses of said inductive device are at least partially a function of the plurality of predetermined frequencies; and

,

a dynamic braking controller coupled to said switching device, said dynamic braking controller configured to open and close said switching device with at least one of the predetermined frequencies to dissipate electric power from the electrical conductor at a predetermined rate by regulating the power losses of said inductive device as a function of the predetermined frequencies.

2. The dynamic braking system in accordance with claim 1, wherein said switching device comprises an insulated gate bipolar transistor (IGBT).

3. The dynamic braking system in accordance with claim 1, wherein said switching device comprises a line side portion of an electric power converter.

4. The dynamic braking system in accordance with claim 1, wherein said dynamic braking controller comprises:

at least one processor; and

,

at least one non-transitory computer-readable storage media coupled to said processor, said non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by said processor, the computer-executable instructions cause said processor to operate said switching device at the predetermined frequencies, thereby regulating the power losses of said inductive device and dissipating electric power from the electrical conductor at the predetermined rate.

5. The dynamic braking system in accordance with claim 1, wherein said dynamic braking controller comprises:

at least one processor; and

,

at least one non-transitory computer-readable storage media coupled to said processor, said non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by said processor, the computer-executable instructions cause said processor to operate said switching device to transmit electric power through said inductive device;

at a first predetermined frequency to convert direct current (DC) power to alternating current (AC) power for transmission to an electric power grid; and

,

a second predetermined frequency, thereby regulating the power losses of said inductive device and dissipating electric power from the electrical conductor at the predetermined rate, wherein the second frequency is greater than the first frequency.

6. The dynamic braking system in accordance with claim 1, further comprising a plurality of monitoring sensors comprising:

at least one monitoring sensor coupled to said inductive device and said dynamic braking controller, said monitoring sensor configured to measure at least one of a voltage and a current on said inductive device; and

,

at least one monitoring sensor coupled to the electrical conductor and said dynamic braking controller, said monitoring sensor configured to measure at least one of a voltage and a current on the electrical conductor, wherein said dynamic braking controller comprises;

at least one processor; and

,

at least one non-transitory computer-readable storage media coupled to said processor, said non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by said processor, the computer-executable instructions cause said processor to operate said switching device at the predetermined frequencies, thereby regulating the power losses of said inductive device and transmitting a predetermined value of current from the electrical conductor as a function of a measured voltage on the electrical conductor.

7. An electric power system comprising:

a direct current (DC) bus; and

,

a dynamic braking system coupled to said DC bus, said dynamic braking system comprising;

an alternating current (AC) bus having power losses that are at least partially a function of a frequency of electric power transmitted therethrough;

a switching device coupled to each of said DC bus and said AC bus, said switching device configured to open and close with a plurality of predetermined frequencies; and

,

a dynamic braking controller coupled to said switching device, said dynamic braking controller configured to open and close the switching device with at least one of the predetermined frequencies to dissipate electric power from said DC bus at a predetermined rate by regulating the power losses of said AC bus as a function of the predetermined frequencies.

8. The electric power system in accordance with claim 7, wherein said switching device comprises an insulated gate bipolar transistor (IGBT).

9. The electric power system in accordance with claim 7, wherein said switching device comprises a plurality of said switching devices defining a line side portion of an electric power converter.

10. The electric power system in accordance with claim 9, further comprising a generator side portion of said electric power converter coupled to one of a rotor of a wind turbine generator and a stator of a wind turbine generator.

11. The electric power system in accordance with claim 7, wherein said dynamic braking controller comprises:

at least one processor; and

,

at least one non-transitory computer-readable storage media coupled to said processor, said non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by said processor, the computer-executable instructions cause said processor to operate said switching device at the predetermined frequencies, thereby regulating the power losses of said AC bus and dissipating electric power from said DC bus at the predetermined rate.

12. The electric power system in accordance with claim 7, wherein said dynamic braking controller comprises:

at least one processor; and

,

at least one non-transitory computer-readable storage media coupled to said processor, said non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by said processor, the computer-executable instructions cause said processor to operate said switching device to transmit electric power through said AC bus;

at a first predetermined frequency to convert DC power to AC power for transmission to an electric power grid; and

,

a second predetermined frequency, thereby regulating the power losses of said AC bus and dissipating electric power from said DC bus at the predetermined rate, wherein the second frequency is greater than the first frequency.

13. The electric power system in accordance with claim 7, further comprising a plurality of monitoring sensors comprising:

at least one monitoring sensor coupled to said AC bus and said dynamic braking controller, said monitoring sensor configured to measure at least one of a voltage and a current on said AC bus; and

,

at least one monitoring sensor coupled to said DC bus and said dynamic braking controller, said monitoring sensor configured to measure at least one of a voltage and a current on said DC bus, wherein said dynamic braking controller comprises;

at least one processor; and

,

at least one non-transitory computer-readable storage media coupled to said processor, said non-transitory computer-readable storage media having computer-executable instructions embodied thereon, wherein when executed by said processor, the computer-executable instructions cause said processor to operate said switching device at the predetermined frequencies, thereby regulating the power losses of said AC bus and transmitting a predetermined value of current from said DC bus as a function of a measured voltage on said DC bus.

14. A method for controlling an electric power system during electrical fault conditions, the electric power system including an electric power generating device, an electric power converter coupled to the electric power generating device, the electric power converter including a switching device, the electric power converter coupled to an electric power grid through an inductive device, and a virtual dynamic braking system including a virtual dynamic braking controller, said method comprising:

operating the switching device at a first frequency;

monitoring at least one electrical condition of the electric power system; and

,

operating the switching device at a second frequency that is different from the first frequency as a function of a value of the monitored electrical condition, thereby regulating power losses of the inductive device and dissipating electric power through the switching device and the inductive device at a predetermined rate.

15. The method in accordance with claim 14, wherein operating the switching device at a second frequency that is different from the first frequency comprises maintaining the electric power generating device in service.

16. The method in accordance with claim 15, wherein maintaining the electric power generating device in service comprises operating the virtual dynamic braking system in conjunction with at least one of:

operation of at least one low voltage ride through (LVRT) feature;

operation of at least one zero voltage ride through (ZVRT) feature;

operation of at least one crowbar system; and

,

operation of a direct current (DC) dynamic brake.

17. The method in accordance with claim 14, wherein monitoring an electrical condition of the electric power system comprises at least one of:

measuring voltage values of a DC bus of the electric power converter;

measuring voltage values of the inductive device;

measuring voltage values of the electric power grid; and

,

measuring values of current transmitted through the inductive device.

18. The method in accordance with claim 17, further comprising operating the switching device at the second frequency, thereby transmitting a predetermined value of current through the inductive device as a function of the measured voltage on the DC bus.

19. The method in accordance with claim 14, wherein operating the switching device at a first frequency comprises transmitting electric power through the inductive device at a first predetermined frequency to convert DC power to alternating current (AC) power for transmission to the electric power grid.

20. The method in accordance with claim 19, wherein operating the switching device at a second frequency that is different from the first frequency comprises increasing the frequency of electric power transmitted through the inductive device.