Synchronous frame regulation to extract a positive sequence component of a line voltage

• US 6,201,715 B1
• Filed: 03/28/2000
• Issued: 03/13/2001
• Est. Priority Date: 03/28/2000
• Status: Expired due to Term

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Huggett, Colin, Kalman, Gabor
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/536,373
• Time in Patent Office: 350 Days
• Field of Search: 363/48, 363/44, 363/39, 363/89, 363/84, 307/105
• US Class Current: 363/48
• CPC Class Codes: H02J 3/1842 wherein at least one reactive element is actively controlled by a bridge converter, e.g. active filters
• CPC Class Codes: H02M 7/219 in a bridge configuration
• CPC Class Codes: H02M 7/53876 based on synthesising a desired voltage vector via the selection of appropriate fundamental voltage vectors, and corresponding dwelling times
• CPC Class Codes: Y02E 40/20 Active power filtering [APF]

Abstract

A power distribution system includes an active rectifier and a controller for the active rectifier. The controller extracts a positive sequence component of a Park vector representing line voltage; and uses the positive sequence component to perform synchronous frame regulation to control the active rectifier.

Claims

1. Apparatus for a power distribution system, the system including a distribution feeder line, the apparatus comprising:

an active rectifier; and

a controller for the active rectifier, the controller determining a positive sequence component of a Park vector representing line voltage, and using the positive sequence component to perform synchronous frame regulation.

2. The apparatus of claim 1, wherein the controller samples the line voltage, samples lying on a locus of the Park vector;

predicts major and minor axes of the locus of the Park vector; and

extracts a positive sequence from the major and minor axes.

3. The apparatus of claim 2, wherein the controller initially determines angle of the positive sequence from the major and minor axes;

and wherein the angle is updated at discrete intervals.

4. The apparatus of claim 3, wherein the controller updates the angle (α

_i+1) by α

_i+1=α

_m+90°

(Δ

T)F, where F is the fundamental frequency of the positive sequence, Δ

T is the time between samples, and α

_m is the angle of one of the major and minor axes.

5. The apparatus of claim 2, wherein the controller updates the fundamental frequency at regular intervals.

6. The apparatus of claim 2, wherein the controller predicts the major and minor axes from at least four samples of the line voltage.

7. The apparatus of claim 1, wherein the controller measures a locus of the Park vector and varies the locus until the locus becomes circular, the positive sequence being a vector defined by the circular locus.

8. The apparatus of claim 7, wherein the controller extracts a unit amplitude Park vector from a voltage Park vector, computes a vector cross product of the voltage Park vector v and a negative sequence unit vector, determines a negative sequence in a negative sequence reference frame from the vector cross product, performs a synchronous-to-stationary reference frame transformation, the result of the transformation being a negative sequence component of the voltage Park vector, and removes the negative sequence component from the voltage Park vector;

whereby the positive sequence component of the voltage Park vector remains.

9. A controller for an active rectifier of a power distribution system, the power distribution system having a distribution feeder line, the controller comprising:

first means for taking samples of line voltage, the samples lying on a locus of a Park vector representing the line voltage;

second means for predicting major and minor axes of the locus of the Park vector; and

third means for extracting a positive sequence component from the major and minor axes.

10. The controller of claim 9, wherein angle of the positive sequence is initially determined from the major and minor axes;

and wherein the angle is updated at discrete intervals.

11. The controller of claim 10, wherein the angle (α

_i+1) is updated by α

_i+1=α

_m+90°

(Δ

T)F, where F is the fundamental frequency of the positive sequence, Δ

T is the time between samples, and α

_m is the angle of one of the major and minor axes.

12. The controller of claim 11, wherein the fundamental frequency is updated at regular intervals.

13. The controller of claim 9, wherein the major and minor axes are predicted from at least four samples of the line voltage.

14. A controller for an active rectifier of a power distribution system, the power distribution system having a distribution feeder line, the controller comprising:

first means for extracting a unit amplitude Park vector from a voltage Park vector representing the line voltage;

second means for computing a vector cross product of the voltage Park vector and a negative sequence unit vector;

third means for determining a negative sequence in a negative sequence reference frame from the vector cross product;

fourth means for performing a synchronous-to-stationary reference frame transformation on the negative sequence reference frame, the result of the transformation being a negative sequence component of the voltage Park vector; and

fifth means for removing the negative sequence component from the voltage Park vector.

15. A method of controlling an active rectifier for a power distribution system, the distribution system including a distribution feeder line, the method comprising the steps of:

determining a positive sequence component of a Park vector representing line voltage; and

using the positive sequence component to perform synchronous frame regulation to control the active rectifier.

16. The method of claim 15, wherein the positive sequence is determined by taking samples of the line voltage, the samples lying on a locus of the Park vector;

predicting major and minor axes of the locus of the Park vector; and

extracting a positive sequence from the major and minor axes.

17. The method of claim 16, wherein an angle of the positive sequence is initially determined from the major and minor axes;

and wherein the angle is updated at discrete intervals.

18. The method of claim 17, wherein the angle (α

_i+1) is updated by (α

_i+1=α

_m+90°

(Δ

T)F, where F is the fundamental frequency of the positive sequence, Δ

T is the time between samples, and α

_m is the angle of one of the major and minor axes.

19. The method of claim 18, wherein the fundamental frequency is updated at regular intervals.

20. The method of claim 15, wherein the positive sequence is determined by extracting a unit amplitude Park vector from a voltage Park vector representing line voltage;

computing a vector cross product of the voltage Park vector and a negative sequence in a negative sequence reference frame unit vector;

determining a negative sequence reference frame from the vector cross product, using the negative sequence to determine a negative sequence component of the voltage Park vector; and

removing the negative sequence component from the voltage Park vector.