DOUBLE FED INDUCTION GENERATOR (DFIG) CONVERTER AND METHOD FOR IMPROVED GRID FAULT RIDETHROUGH

• US 20130249501A1
• Filed: 03/26/2012
• Published: 09/26/2013
• Est. Priority Date: 03/26/2012
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Lu, Haihui, Yuan, Zhenhuan, Wei, Lixiang, Kerkman, Russel, Lukaszewski, Richard, Mohamed Sayed Ahmed, Ahmed
• Granted Patent: US 9,041,234 B2
• Time in Patent Office: Days
• US Class Current: 322/21
• CPC Class Codes: F03D 7/0224 Adjusting blade pitch
• CPC Class Codes: F03D 7/0284 in relation to the state of the electric grid
• CPC Class Codes: F03D 7/0288 in relation to clearance between the blade and the tower, i.e. preventing tower strike
• CPC Class Codes: F03D 7/04 Automatic control; Regulation
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: H02H 7/06 for dynamo-electric generators; for synchronous capacitors
• CPC Class Codes: H02H 7/12 for static converters or rectifiers for discharge lamp power supplies using static converters H05B41/2851, H05B41/2921, H05B41/2981
• CPC Class Codes: H02H 9/002 limiting inrush current on switching on of inductive loads subjected to remanence, e.g. transformers
• 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: H02P 2101/15 for wind-driven turbines
• 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 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• 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 double fed induction generator (DFIG) converter method are presented in which rotor side current spikes are attenuated using series-connected damping resistance in response to grid fault occurrences or grid fault clearances.

Claims

1. A power conversion system for a double fed induction generator (DFIG), comprising:

a rotor side converter comprising a plurality of AC connections coupleable to rotor leads of the DFIG and a plurality of DC connections coupled with a DC circuit;

a grid side converter comprising a plurality of DC connections coupled with the DC circuit and a plurality of AC connections coupleable to stator leads of the DFIG;

a series damping apparatus coupled in series between the rotor leads of the DFIG and the grid side converter, the series damping apparatus comprising at least one series damping circuit including a series damping circuit resistance coupled in series between one of the rotor leads of the DFIG and the grid side converter, and a series damping switching circuit coupled in parallel with the series damping circuit resistance, the series damping switching circuit operative in a first mode to bypass the series damping circuit resistance to prevent current flow in the series damping circuit resistance and in a second mode to allow current to flow in the series damping circuit resistance; and

a damping controller operative to control the mode of the series damping switching circuit based at least partially on a grid fault occurrence or a grid fault clearance.

2. The power conversion system of claim 1, wherein the series damping apparatus comprises at least two series damping circuits individually coupled between a corresponding one of the rotor leads of the DFIG and a corresponding one of the AC connections of the rotor side converter.

3. The power conversion system of claim 2, wherein the series damping apparatus comprises a plurality of series damping circuits individually coupled between a corresponding one of the rotor leads of the DFIG and a corresponding one of the AC connections of the rotor side converter, with a series damping circuit connected in series with each one of the rotor leads of the DFIG.

4. The power conversion system of claim 2, wherein the series damping switching circuits are bidirectional.

5. The power conversion system of claim 2, wherein the damping controller is operative to provide a damping control signal to the series damping apparatus to set the mode of the damping switching circuits, and wherein the damping controller provides the damping control signal to set the damping switching circuits to the second mode for a fixed time in response to a detected grid fault occurrence or in response to a detected grid fault clearance.

6. The power conversion system of claim 2, wherein the damping controller is operative to provide a damping control signal to the series damping apparatus to set the mode of the damping switching circuits, and wherein the damping controller provides the damping control signal to set the damping switching circuits to the second mode for an adjustable time period in response to a detected grid fault occurrence or in response to a detected grid fault clearance and thereafter provides damping control signal to set the damping switching circuits to the first mode based on a monitored stator or rotor current value.

7. The power conversion system of claim 1, wherein the series damping apparatus comprises at least at least one series damping circuit coupled between the DC connections of the rotor side converter and the DC connections of the grid side converter.

8. The power conversion system of claim 7, wherein the series damping apparatus comprises a plurality of series damping circuits coupled between the DC connections of the rotor side converter and the DC connections of the grid side converter.

9. The power conversion system of claim 7, wherein the at least one series damping switching circuit is bidirectional.

10. The power conversion system of claim 4, wherein the at least one series damping switching circuit is bidirectional.

11. The power conversion system of claim 2, wherein the damping controller is operative to provide a damping control signal to the series damping apparatus to set the mode of the at least one damping switching circuit, and wherein the damping controller provides the damping control signal to set the at least one damping switching circuit to the second mode for a fixed time in response to a detected grid fault occurrence or in response to a detected grid fault clearance.

12. The power conversion system of claim 1, wherein the damping controller is operative to provide a damping control signal to the series damping apparatus to set the mode of the at least one damping switching circuit, and wherein the damping controller provides the damping control signal to set the at least one damping switching circuit to the second mode for an adjustable time period in response to a detected grid fault occurrence or in response to a detected grid fault clearance and thereafter provides damping control signal to set the at least one damping switching circuit to the first mode based on a monitored stator or rotor current value.

13. The power conversion system of claim 1:

wherein the rotor side converter comprises a rotor side rectifier circuit and a rotor side switching circuit, wherein the rotor side converter is operative when a rotor speed of the DFIG is above a nominal value to provide power from the rotor leads to the DC circuit using the rotor side rectifier circuit, and wherein the rotor side converter is operative when the rotor speed is below the nominal value to provide power from the DC circuit to the rotor leads using the rotor side rectifier circuit; and

wherein the grid side converter comprises a grid side rectifier circuit and a grid side switching circuit, wherein the grid side converter is operative when the rotor speed is above the nominal value to provide power from the DC circuit to the stator leads using the grid side switching circuit, and wherein the grid side converter is operative when the rotor speed is below the nominal value to provide power from the stator leads to the DC circuit using the grid side rectifier circuit.

14. A method of operating a converter for a double fed induction generator (DFIG), the method comprising:

selectively activating at least one series damping circuit to conduct current through a series damping circuit resistance coupled in series between one of a plurality of rotor leads of a rotor of the DFIG and a grid side converter of the converter in response to a grid fault occurrence or a grid fault clearance; and

selectively bypassing the series damping circuit resistance to prevent current flow in the series damping circuit resistance a time period after activating the at least one series damping circuit.

15. The method of claim 14, further comprising monitoring at least one operating condition of the DFIG and adjusting the time period based at least partially on the at least one operating condition of the DFIG.

16. The method of claim 14, wherein selectively activating the at least one series damping circuit comprises conducting AC current through the series damping circuit resistance coupled in series between one of a plurality of rotor leads of the rotor and a rotor side converter of the converter in response to the grid fault occurrence or the grid fault clearance.

17. The method of claim 14, wherein selectively activating the at least one series damping circuit comprises conducting DC current through the series damping circuit resistance coupled in series between one a rotor side converter of the converter and the grid side converter in response to the grid fault occurrence or the grid fault clearance.

18. A computer readable medium comprising computer executable instructions for operating a converter for a double fed induction generator (DFIG), the computer readable medium comprising computer executable instructions for:

selectively activating at least one series damping circuit to conduct current through a series damping circuit resistance coupled in series between one of a plurality of rotor leads of a rotor of the DFIG and a grid side converter of the converter in response to a grid fault occurrence or a grid fault clearance; and

selectively bypassing the series damping circuit resistance to prevent current flow in the series damping circuit resistance a time period after activating the at least one series damping circuit.

19. The computer readable medium of claim 18, further comprising computer executable instructions for monitoring at least one operating condition of the DFIG and adjusting the time period based at least partially on the at least one operating condition of the DFIG.

20. The computer readable medium of claim 18, further comprising computer executable instructions for conducting AC current through the series damping circuit resistance coupled in series between one of a plurality of rotor leads of the rotor and a rotor side converter of the converter in response to the grid fault occurrence or the grid fault clearance.

21. The computer readable medium of claim 18, further comprising computer executable instructions for conducting DC current through the series damping circuit resistance coupled in series between one a rotor side converter of the converter and the grid side converter in response to the grid fault occurrence or the grid fault clearance.