Wind turbine generator system

• US 7,355,296 B2
• Filed: 02/27/2007
• Issued: 04/08/2008
• Est. Priority Date: 01/08/2004
• Status: Active Grant

• Current Assignee: Hitachi Industrial Products, Ltd. (Hitachi, Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Ichinose, Masaya, Futami, Motoo, Sakai, Hiromitsu
• Primary Examiner(s): Ponomarenko; Nicholas
• Application Number:
  US11/679,759
• Publication Number:
  US 20070200348A1
• Time in Patent Office: 406 Days
• Field of Search: 290/43, 290/44, 290/54, 290/55, 322/23, 322/24, 322/25, 322/37
• US Class Current: 290/44
• CPC Class Codes: F03D 7/026 for starting-up
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: F05B 2270/337 Electrical grid status parameters, e.g. voltage, frequency or power demand
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/007 Control circuits for doubly fed generators
• CPC Class Codes: H02P 9/10 Control effected upon generator excitation circuit to reduce harmful effects of overloads or transients, e.g. sudden application of load, sudden removal of load, sudden change of load
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

To shorten a startup interval to reach a synchronizing condition, a phase difference and an amplitude difference between the grid voltage and the stator voltage of one phase of a winding are obtained. The difference in amplitude is decreased prior to or in parallel to synchronizing the stator voltage with the grid voltage. The calculated compensation phase compensation value is used as an initial value for synchronizing at the next synchronizing operation.

Claims

1. A wind turbine generator system including a doubly fed generator having a stator and a rotor, a switch arranged on a side of the stator for linkage with a grid, and a converter for exciting a secondary winding of the doubly fed generator, the rotor being coupled to a wind turbine for generating electric power, comprising:

detecting means for detecting a stator voltage at the switch on the side of the stator and a grid voltage at the switch on a side of the grid; and

controlling means for controlling the converter to excite the secondary winding while the switch is open and closing the switch when the phase of the stator voltage is identical with the phase of the grid voltage.

2. The wind turbine generator system as claimed in claim 1, wherein the controlling means further controls the converter to excite the secondary winding so as to decrease a difference in amplitude between the stator voltage and the grid voltage.

3. The wind turbine generator system as claimed in claim 1, wherein the controlling means closes the switch when the stator voltage is identical with the grid voltage in amplitude.

4. The wind turbine generator system as claimed in claim 2, wherein the controlling means closes the switch when the stator voltage is identical with the grid voltage in amplitude.

8. The method as claimed in claim 1, wherein the converter is further controlled to excite the secondary winding so as to decrease a difference in amplitude between the stator voltage and the grid voltage.

10. The method as claimed in claim 8, further comprising the step of:

closing the switch when the stator voltage is identical with the grid voltage in amplitude.

5. A wind turbine generator system including a doubly fed generator having a stator and a rotor, a switch arranged on a side of the stator for linkage with a grid, and a converter for exciting a secondary winding of the doubly fed generator, the rotor being coupled to a wind turbine for generating electric power, comprising:

first detecting means for detecting a stator voltage at the switch on a side of the stator;

second detecting means for detecting a grid voltage at the switch on a side of the grid;

third detecting means for detecting a rotation phase of the doubly fed generator;

calculating means for calculating a slip frequency from a phase of the grid voltage and the rotation phase;

phase controlling means for controlling the converter to excite the secondary winding on the basis of the slip frequency so as to decrease a difference between a phase of the stator voltage and a phase of the grid voltage, when the switch is open; and

controlling means for closing the switch when the phase of the stator voltage is identical with the phase of the grid voltage.

6. The wind turbine generator system as claimed in claim 5, wherein the controlling means closes the switch when the stator voltage is identical with the grid voltage in amplitude.

7. A method of controlling a wind turbine generator system including a doubly fed generator having a stator and a rotor, a switch arranged on a side of the stator for linkage with a grid, and a converter for exciting a secondary winding of the doubly fed generator, the rotor being coupled to a wind turbine for generating electric power, comprising the steps of:

detecting a stator voltage at the switch on a side of the stator and a grid voltage at the switch on a side of the grid; and

controlling the converter to excite the secondary winding while the switch is open and closing the switch when a phase of the stator voltage is identical with a phase of the grid voltage.

9. The method as claimed in claim 7, further comprising the step of:

closing the switch when the stator voltage is identical with the grid voltage in amplitude.