Apparatus for removing harmonic components of an electric power frequency generated in electric power generation equipment

• US 5,559,421 A
• Filed: 03/04/1994
• Issued: 09/24/1996
• Est. Priority Date: 03/09/1993
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Miyakawa, Kado
• Primary Examiner(s): Dougherty, Thomas M.
• Assistant Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US08/205,808
• Time in Patent Office: 935 Days
• Field of Search: 322/7, 322/10, 322/13, 363/39, 363/34, 290/46
• US Class Current: 322/58
• CPC Class Codes: H02M 1/12 Arrangements for reducing harmonics from ac input or output
• CPC Class Codes: H02P 9/02 Details
• CPC Class Codes: H02P 9/08 Control of generator circuit during starting or stopping of driving means, e.g. for initiating excitation

Abstract

In a generator starting apparatus, in which commercial frequency electric power supplied from an electric power system is converted into variable-voltage variable-frequency electric power to thereby start a gas turbine generator, a harmonic-component removing apparatus is provided which removes harmonic components contained in the converted variable-voltage variable-frequency electric power on the basis of the detected harmonic components. In addition, an apparatus for removing harmonic components generated in an electric power equipment is provided, wherein harmonic components contained in an electric power system are detected so that they may be removed.

Claims

1. An apparatus for removing harmonic components of electric power frequency generated in electric power equipment, said apparatus comprising:

a first electric generator;

a second electric generator;

a first frequency converter connected to said first and second generators;

a second frequency converter connected to said first and second generators;

means for supplying electricity from an electric power system to said first and second frequency converters, to supply variable-voltage, variable-frequency electric power to a selected one of said first and second generators to make said selected one of said generators operate as a motor, to thereby start said selected one of said generators;

a first transformer connected to said first generator;

a second transformer connected to said second generator;

switching means for alternatively connecting a selected one of said first transformer and said second transformer to the electric power system, to supply electric power from the selected one of said first and second generators to the electric power system;

a detector for detecting harmonic components of an electric power frequency contained in the electric power supplied from said first frequency converter to the selected one of said first and second generators; and

an active filter for removing the harmonic components of the electric power frequency contained in the electric power supplied from said first frequency converter, said active filter including said second frequency converter.

2. An apparatus according to claim 1, wherein said first and second generators are gas turbine generators, and starting of said one of said generators starts the gas turbine of said one of said generators.

3. An apparatus according to claim 1, wherein each of said frequency converters includes:

an electric power rectifier for converting commercial AC power supplied from the electric power system into DC power; and

an electric power inverter for converting DC power supplied from said electric power rectifier into variable-voltage variable-frequency AC power.

4. An apparatus according to claim 1, wherein said detector includes:

means for detecting a current which flows on a line connecting said first frequency converter and said one of said first and second generators; and

an FFT for extracting harmonic components of required electric power flowing on said line from the current detected by said detecting means.

5. An apparatus according to claim 1, wherein said active filter includes:

an active filter controller for generating a control signal on the basis of the harmonic components detected by said detector;

means for applying the control signal to said second frequency converter to remove the harmonic components of the electric power frequency.

6. An apparatus according to claim 5, wherein said electric power rectifier includes a self arc-extinguishing semiconductor switching device.

7. An apparatus for removing harmonic components of electric power generated in electric power equipment, said apparatus comprising:

a first electric generator;

a second electric generator;

a first frequency converter connected to an electric power system to provide variable-voltage, variable-frequency electric power;

first switching means for connecting said first frequency converter to a selected one of said first and second generators to make said selected one of said generators operate as a motor, to thereby start said selected one of said generators;

a first transformer connected to said first generator;

a second transformer connected to said second generator;

second switching means for connecting a selected one of said first transformer and said second transformer to the electric power system, to supply electric power as generated by the selected one of said first and second generators to the electric power system;

a detector for detecting harmonic components contained in the electric power supplied from said first frequency converter to the selected one of said first and second generators; and

an active filter for removing the detected harmonic components, said active filter including a second frequency converter connected to said first and second generators and means for supplying electricity from the electric power system to said second frequency converter.