Harmonic mitigating method and apparatus

• US 6,549,434 B2
• Filed: 09/20/2001
• Issued: 04/15/2003
• Est. Priority Date: 09/20/2001
• Status: Expired due to Term

• Current Assignee: Rockwell Technologies, LLC (Teledyne Technologies Incorporated)
• Original Assignee: Rockwell Automation Technologies Incorporated (Rockwell Automation, Inc.)
• Inventors: Zhou, Dongsheng, Skibinski, Gary L., Buchholz, Brian R., Maslowski, Walt A., Guskov, Nick N.
• Primary Examiner(s): Berhane, Adolf Denske
• Application Number:
  US09/956,780
• Publication Number:
  US 20030053320A1
• Time in Patent Office: 572 Days
• Field of Search: 363/39, 363/40, 363/41, 363/95, 363/97, 363/98, 323/207, 323/200, 323/211, 307/105
• US Class Current: 363/39
• CPC Class Codes: H02J 3/01 Arrangements for reducing harmonics or ripples
• CPC Class Codes: H02M 1/126 using passive filters
• CPC Class Codes: Y02E 40/40 Arrangements for reducing harmonics

Abstract

A harmonic mitigating apparatus connected between a three phase power source and a load provides a multiple-winding reactor for reducing harmonics directed from the load to the source, the apparatus including, for each system phase, first and second line windings in series between the source and load and oriented so as to have the same polarity such that the winding fluxes add thereby increasing total reactance to harmonics directed from the load to the supply, the apparatus also including at least one trap circuit including a series inductance and capacitor for each phase and linked between the first and second line windings and a neutral point (or another phase), the trap circuit characterized by a reactance that is lower than the reactance of the first line winding such that harmonics flow into the trap circuit, for each phase, at least two of the first and second line windings and the trap winding arranged on the same core.

Claims

1. The apparatus for mitigating harmonic currents generated by a load connected to a power distribution source via a supply line, the apparatus comprising:

first and second magnetic cores;

first and second series line windings linked between the supply line and the load; and

at least one trap circuit including a series linked capacitor and trap winding linked at an intermediate node between the first and second line windings and an output connected to a second line;

wherein the first and trap windings are disposed on the first magnetic core and the second winding is disposed on the second core.

2. The apparatus of claim 1 further including a capacitor in series with the trap winding between the first and second lines.

3. The apparatus of claim 1 wherein the source and load are three phase, the supply line is a first supply line, the first and second series windings are a first set of series windings and the load is also linked to the source via second and third supply lines and, wherein, the apparatus further includes:

a second set of series windings including first and second series line windings linked between the second supply line and the load;

a second trap circuit including a series linked capacitor and trap winding linked at a second intermediate node between the first and second line windings of the second set;

a third set of series windings including first and second series line windings linked between the third supply line and the load; and

a third trap circuit including a series linked capacitor and trap winding linked at a third intermediate node between the first and second line windings of the third set;

wherein, each of the first windings and each of the trap windings is disposed on the first core and each of the second windings is disposed on the second core.

4. An apparatus for mitigating harmonic currents generated by a load connected to a power distribution source via a supply line, the apparatus comprising:

at least one magnetic core including a first core;

first and second line windings in series between a supply line and the load such that the first and second line windings are disposed on the first core so as to have the same polarity; and

at least one trap circuit including a series linked capacitor and trap winding linked to an intermediate node between the first and second line windings with an output connected to a second line, the trap winding disposed on the at least one core;

wherein, a reactance to harmonic currents between the load and the source is increased by the summation of fluxes generated by the line windings and a selected portion of the harmonic currents is diverted through the trap circuit.

5. The apparatus of claim 4 wherein the at least one core includes a second core and the trap winding is disposed on the second core.

6. The apparatus of claim 4 wherein the source and load are three phase, the first line winding includes a separate first line winding for each phase the second line winding includes a separate second line winding for each phase and the trap winding includes a separate trap winding for each phase.

7. The apparatus of claim 4 wherein the second line is a neutral point.

10. The apparatus of claim 4 wherein the at least one core consists of the first core.

8. A method for mitigating harmonic currents generated by a load connected to a power distribution source via a supply line, the method comprising the steps of:

providing first and second magnetic cores;

providing first and second series line windings linked between the supply line and the load; and

providing at least one trap circuit including a series linked capacitor and trap winding linked at an intermediate node between the first and second line windings and an output connected to a second line;

disposing the first and trap windings on the first magnetic core and the second winding on the second core.

9. The method of claim 8 wherein the source and load are three phase, the supply line is a first supply line, the first and second series windings are a first set of series windings and the load is also linked to the source via second and third supply lines and, wherein, the apparatus further includes:

a second set of series windings including first and second series line windings linked between the second supply line and the load;

a second trap circuit including a series linked capacitor and trap winding linked at a second intermediate node between the first and second line windings of the second set;

a third set of series windings including first and second series line windings linked between the third supply line and the load; and

a third trap circuit including a series linked capacitor and trap winding linked at a third intermediate node between the first and second line windings of the third set;

wherein, each of the first windings and each of the trap windings is disposed on the first core and each of the second windings is disposed on the second core.

11. A method for mitigating harmonic currents generated by a load connected to a power distribution source, the method comprising the steps of:

providing at least one magnetic core including a first core;

providing first and second line windings and a trap winding;

disposing the first and second windings on the first core so as to have the same polarity;

linking the first and second line windings in series between a supply line and the load;

disposing the trap winding on the at least one core; and

linking the trap winding to an intermediate node between the first and second line windings with an output linked to a second line;

wherein, a reactance between the load and the source is increased by the summation of fluxes generated by the line windings and a selected portion of the harmonic currents is diverted through the trap circuit.

12. The method of claim 11 wherein the step of providing at least one core includes providing the first and a second cores and wherein the step of disposing the trap winding includes disposing the trap winding on the second core.

13. The method of claim 11 wherein the step of providing at least one core includes the step of providing the first core.

14. An apparatus for mitigating harmonic currents generated by a load connected to a power distribution source, the apparatus comprising:

a single magnetic core;

first and second series line windings disposed on the core, the first winding linked to the source and the second winding linked to the load, the first and second line windings disposed such that the first and second windings have the same polarity; and

at least one trap circuit including a series linked capacitor and trap winding linked at an intermediate node between the first and second line windings and an output connected to a second line;

wherein, a reactance between the load and the source is increased by the summation of fluxes generated by the line windings and a selected portion of the harmonic currents is diverted through the trap circuit.