Wind Power Generation System

• US 20080143111A1
• Filed: 12/12/2007
• Published: 06/19/2008
• Est. Priority Date: 12/14/2006
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ichinose, Masaya, Futami, Motoo, Matsutake, Mitsugu, Oohara, Shinya
• Granted Patent: US 7,728,451 B2
• Time in Patent Office: Days
• US Class Current: 290/44
• CPC Class Codes: F03D 7/028 controlling wind motor output power
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: F05B 2220/70642 of the synchronous type
• CPC Class Codes: H02P 21/22 Current control, e.g. using a current control loop
• 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: Y02E 10/72 Wind turbines with rotation axis in wind direction

Abstract

A wind power generation system includes: a wind turbine in which at least one blade is mounted on an axis; a generator for generating multiphase alternating current power by rotation of the axis; and a multiphase power conversion device for performing PWM-control for adjustment and output of generated power of the generator. With the configuration, the PWM-control provides for each phase a control paused period in which no overlap occurs. Thus, the pulse density between the control period and the control paused period of other phases is low, thereby generating high and low density in an inter-phase pulse.

Claims

1. A wind power generation system comprising:

a wind turbine in which at least one blade 120a is mounted on an axis;

a generator for generating multiphase alternating current power by rotation of the axis; and

a power conversion device for performing PWM-control for adjustment and output of generated power of the generator wherein

the power conversion device performs the PWM-control by providing for each phase a control paused period in which no overlap occurs.

2. The wind power generation system according to claim 1, wherein:

the power conversion device performs the PWM-control by comparing the command value based on a frequency of a connected terminal voltage with a triangular wave; and

the frequency of the triangular wave is 6n (n is a positive integer) times as high as a frequency of the terminal voltage.

3. The wind power generation system according to claim 1, wherein

the power conversion device provides the control paused period when a rotation speed of the generator is equal to or less than, or more than a predetermined value.

4. The wind power generation system according to claim 3, wherein

the predetermined value is obtained by an amount of heat of a switching element.

11. The wind power generation system according to claim 1, wherein:

the generator is a permanent magnetic generator;

the power conversion device comprises a first power converter capable of bidirectionally converting AC power and DC power;

a capacitor for storing the DC power; and

a second power converter capable of bidirectionally converting DC power and AC power; and

a coil side of the permanent magnetic generator is connected to an alternating current side of the first power converter, and an alternating current side of the second power converter is connected to a power system.

12. The wind power generation system according to claim 1, wherein:

the generator is a synchronous generator;

the power conversion device comprises a first power converter capable of bidirectionally converting AC power and DC power;

a capacitor for storing the DC power; and

a second power converter capable of bidirectionally converting DC power and AC power; and

a stator side of the synchronous generator is connected to an alternating current side of the, an alternating current side of the second power converter is connected to a power system, and the period is determined by a system frequency of the power system.

5. A wind power generation system comprising:

a wind turbine in which at least one blade is mounted on an axis;

a generator for generating multiphase alternating current power by rotation of the axis; and

a power conversion device for performing PWM-control for adjustment and output of generated power of the generator wherein

the power conversion device performs the PWM-control by changing inter-phase pulse density.

6. The wind power generation system according to claim 5, wherein

the power conversion device changes four times the pulse density in a period.

7. The wind power generation system according to claim 5, wherein

the power conversion device performs the PWM-control with a short-circuit prevention period for preventing a short circuit of a serially connected switching element;

and

a value corresponding to an amount of deficiency by the short-circuit prevention period is added to a command value of each phase.

8. The wind power generation system according to claim 5, further comprising

blade angle change means for changing an angle of the blade based on wind velocity.

9. The wind power generation system according to claim 5, wherein:

the generator is a wound-rotor induction generator in which a coil is wound on a stator side and a rotor side;

the power conversion device comprises a first power converter capable of bidirectionally converting AC power and DC power;

a capacitor for storing the DC power; and

a second power converter capable of bidirectionally converting DC power and AC power;

one coil of the wound-rotor induction generator is connected to a power system, and another coil is connected to the first power converter; and

an alternating current side of the second power converter is connected to the power system.

10. The wind power generation system according to claim 9, wherein:

a low pass filter is inserted between an alternating current side of the second power converter and the power system; and

pulse density of an inter-phase voltage on an input side of the low pass filter changes.