POWER CONVERTER FOR DOUBLY-FED POWER GENERATOR SYSTEM

• US 20070210651A1
• Filed: 01/18/2007
• Published: 09/13/2007
• Est. Priority Date: 03/10/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ichinose, Masaya, Futami, Motoo, Oohara, Shinya, Imazu, Yasuhiro
• Granted Patent: US 7,485,980 B2
• Time in Patent Office: Days
• US Class Current: 307/64
• CPC Class Codes: H02P 21/00 Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
• CPC Class Codes: H02P 9/007 Control circuits for doubly fed generators
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

An excitation power converter of a doubly-fed generator is protected from excess current to be caused by ground fault or system disturbance and operation continuity of the power converter is ensured. In a power converter system, in order not to flow excess current generated in secondary windings of the doubly-fed generator into the power converter, a rectifier is connected in parallel to the power converter via a reactor, a DC link of the rectifier is connected to a DC link of the power converter, excess current flowing from the secondary windings is separately flowed at a reactor impedance ratio to reduce an amount of current flowing into the power converter, and a semiconductor switching element of an excess current generation arm of the power converter is set to an on-state.

Claims

1. A generator in which a stator side of a doubly-fed generator is connected to a power system and an excitation power converter is connected to secondary windings of said doubly-fed generator to adjust generation of a power to be output from said doubly-fed generator to said power system, wherein:

said excitation power converter is connected to the secondary windings of said doubly-fed generator via a first impedance;

a diode rectifier is connected in parallel to the second windings of said doubly-fed generator via a second impedance; and

a DC link of said diode rectifier is connected in parallel to a DC link of said excitation power converter,

wherein the generator comprises a controller for outputting an on-command to a power semiconductor switching element of said excitation power converter if a value of current flowing in the power semiconductor switching element is a predetermined value or larger.

2. The generator according to claim 1, wherein said first and second impedances are reactors.

3. The generator according to claim 1, wherein a value of said first impedance is larger than a value of said second impedance.

4. The generator according to claim 1, wherein an energy consuming load is connected to the DC link of said diode rectifier.

5. The generator according to claim 1, wherein said controller is provided with an excess current suppressing controller receives said predetermined value and a value of current flowing into said power semiconductor switching elements and output the on-command.

6. A generator in which a stator side of a doubly-fed generator is connected to a power system and an excitation power converter is connected to secondary windings of said doubly-fed generator to adjust generation of a power to be output from said doubly-fed generator to said power system, wherein:

said excitation power converter comprises a first power converter whose AC terminal side is connected to said second windings via a first impedance and whose DC terminal side is connected to a smoothing capacitor, and a second power converter whose DV terminal side is connected to said smoothing capacitor and whose AC terminal side is connected to the power system;

a diode rectifier is connected in parallel to the second windings of said doubly-fed generator via a second impedance; and

a DC link of said diode rectifier is connected in parallel to a DC link of said excitation power converter,

wherein the generator comprises a controller for outputting an on-command to a power semiconductor switching element of said excitation power converter if a value of current flowing in the power semiconductor switching element is a predetermined value or larger.

7. The generator according to claim 6, wherein said first and second impedances are reactors.

8. The generator according to claim 6, wherein a value of said first impedance is larger than a value of said second impedance.

9. The generator according to claim 6, wherein an energy consuming load is connected to the DC ling of said diode rectifier.

10. The generator according to claim 6, wherein said controller is provided with an excess current suppressing controller receives said predetermined value and a value of current flowing into said power semiconductor switching elements and output the on-command.

11. A generator in which a stator side of a doubly-fed generator is connected to a power system and an excitation power converter is connected to secondary windings of said doubly-fed generator to adjust generation of a power to be output from said doubly-fed generator to said power system, wherein:

said excitation power converter is rotated by a wind mill;

said excitation power converter comprises a first power converter whose AC terminal side is connected to said second windings via a first impedance and whose DC terminal side is connected to a smoothing capacitor, and a second power converter whose DC terminal side is connected to said smoothing capacitor and whose AC terminal side is connected to the power system;

a diode rectifier is connected in parallel to the second windings of said doubly-fed generator via a second impedance; and

a DC link of said diode rectifier is connected in parallel to a DC link of said excitation power converter,

wherein the generator comprises a controller for outputting an on-command to an IGBT of said excitation power converter if a value of current flowing in the IGBT is a predetermined value or larger.