Variable speed distributed drive train wind turbine system

• US 7,042,110 B2
• Filed: 02/04/2004
• Issued: 05/09/2006
• Est. Priority Date: 05/07/2003
• Status: Expired due to Fees

• Current Assignee: Clipper Windpower, LLC
• Original Assignee: Clipper Windpower Technology, Inc.
• Inventors: Erdman, William, Cousineau, Kevin L., Mikhail, Amir S., Howes, Lawrence H., Holley, William
• Primary Examiner(s): Schuberg, Darren
• Assistant Examiner(s): Cuevas, Pedro J.
• Application Number:
  US10/773,851
• Publication Number:
  US 20050012339A1
• Time in Patent Office: 825 Days
• Field of Search: 290/44, 290/55, 290/40.C
• US Class Current: 290/44
• CPC Class Codes: F03D 15/10 using gearing not limited to rotary motion, e.g. with oscillating or reciprocating members
• CPC Class Codes: F03D 7/0224 Adjusting blade pitch
• CPC Class Codes: F03D 7/0272 by measures acting on the electrical generator
• CPC Class Codes: F03D 7/0276 controlling rotor speed, e.g. variable speed
• CPC Class Codes: F03D 7/028 controlling wind motor output power
• CPC Class Codes: F03D 7/0284 in relation to the state of the electric grid
• CPC Class Codes: F03D 7/042 by means of an electrical or electronic controller
• CPC Class Codes: F03D 7/048 controlling wind farms
• CPC Class Codes: F03D 9/25 the apparatus being an electrical generator F03D9/22 takes precedence
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: F03D 9/257 the wind motor being part of a wind farm
• CPC Class Codes: F05B 2210/16 Air or water being indistinctly used as working fluid, i.e. the machine can work equally with air or water without any modification
• CPC Class Codes: F05B 2270/1016 in variable speed operation
• CPC Class Codes: F05B 2270/1032 Torque
• CPC Class Codes: F05B 2270/337 Electrical grid status parameters, e.g. voltage, frequency or power demand
• CPC Class Codes: H02J 2300/20 The dispersed energy generation being of renewable origin
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/0012 Contingency detection
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/40 : Synchronising a generator for connection to a network or to another generator
• CPC Class Codes: H02P 2101/10 : for water-driven turbines
• CPC Class Codes: H02P 2101/15 : for wind-driven turbines
• CPC Class Codes: H02P 5/747 : mechanically coupled by gearing
• CPC Class Codes: H02P 9/02 : Details
• CPC Class Codes: H02P 9/04 : Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• 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: H02P 9/102 : for limiting effects of transients
• CPC Class Codes: H02P 9/105 : for increasing the stability
• CPC Class Codes: H02P 9/107 : for limiting effects of overloads
• CPC Class Codes: Y02E 10/56 : Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 10/72 : Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y02E 10/76 : Power conversion electric or electronic aspects

Abstract

A variable speed wind turbine employing a rotor connected to a multiplicity of synchronous generators with wound field or permanent magnet rotors. A passive rectifier and an inverter are used for power transfer back to the grid. A Turbine Control Unit (TCU) commands a required generator torque based on rotor speed and power output of the turbine inverters. Torque is controlled by regulating the DC current by control of the inverter. A main-shaft-damping filter is provided by measurement of the DC bus voltage. In high winds the turbine remains at a constant average output power through a constant torque command and a varying pitch command to a rotor pitch servo system. A set point is fixed at the inverter output such that output VAR load is minimized running the turbine at very nearly unity power factor. Dynamic VAR and power factor control is provided by a separate VAR apparatus.

Claims

1. An electric power-generating device comprising:

a main input shaft rotated by a source of energy;

one or more sensors, an output thereof being sensor information;

a synchronous generator selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said synchronous generator being operatively connected to said main input shaft, an output of said synchronous generator being AC electrical power;

a rectifier connected to said output of said synchronous generator, an output of said rectifier being DC electrical power;

an active inverter capable of regulating DC current, said active inverter having a first input, a second input, and an output, said first input being connected to said output of said rectifier; and

,

a control unit connected to said one or more sensors and to said second input of said active inverter, said control unit capable of causing said active inverter to regulate said DC current of said active inverter in accordance with said sensor information.

2. The electric power-generating device of claim 1 wherein said device includes a plurality of synchronous generators operatively connected to said main input shaft.

3. The electric power-generating device of claim 2 wherein said control unit brings each generator of said plurality of synchronous generators online sequentially in the event of low energy conditions of said source of energy to improve system efficiency at low power.

4. The electric power-generating device of claim 3 wherein said control unit alternates the sequence in which said control unit shifts the order in which said generators are brought online such that each generator receives similar utilization.

5. The electric power-generating device of claim 1 wherein electric power-generating device is a wind turbine that includes said generator and said rectifier, said wind turbine being located at the top of a tower and wherein said inverter is located at the bottom of said tower.

6. The electric power-generating device of claim 5 wherein a set of power cables conduct electrical power from the top of said tower to the bottom of said tower and wherein said power cables conduct DC electrical power.

7. The electric power-generating device of claim 6 wherein said set of power cables consist of two cables per generator.

8. The electric power-generating device of claim 1 wherein said rectifier comprises a plurality of diodes that convert AC electrical power into DC electrical power.

9. The electric power-generating device of claim 8 wherein said generator is a three-phase synchronous generator and wherein said rectifier comprises six diodes.

10. The electric power-generating device of claim 1 wherein said control unit controls generator torque by regulating the current in said DC electrical power.

11. The electric power-generating device of claim 10 wherein the voltage of said DC electrical power is measured and used as an input to said control unit.

12. The electric power-generating device of claim 11 further comprising a band pass filter for said measured voltage of said DC electrical power that is tuned to measure vibrations in mechanical portions of said electric power-generating device at a predetermined resonant frequency and wherein said control unit provides a generator torque signal to said inverter that cancels and dampens said vibrations.

13. The electric power-generating device of claim 1 wherein said control unit measures vibrations in mechanical portions of said electric power-generating device and controls generator torque to actively dampen said vibrations.

14. The electric power-generating device of claim 13 wherein said control unit measures said vibrations by measuring the voltage of said DC electrical power.

15. The electric power-generating device of claim 14 further comprising a band pass filter in said control unit to filter said measured voltage of said DC electrical power to a predetermined frequency that corresponds to a mechanical resonance in said mechanical portions of said electric power-generating device.

16. A fluid-flow turbine comprising:

a blade for converting fluid-flow power into mechanical power;

one or more sensors, an output thereof being sensor information;

a plurality of synchronous generators selected from the group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said synchronous generators being operatively connected to said blade for converting said mechanical power into fixed-frequency utility-connected AC electrical power;

a plurality of rectifiers electrically connected to each of said synchronous generators for converting said AC electrical power of each synchronous aenerator into DC electrical power;

a plurality of active inverters electrically connected to each of said plurality of rectifiers to convert said DC electrical power of each of said plurality of rectifiers into AC electrical power, each active inverter capable of regulating DC electrical current; and

,

a control unit connected to said one or more sensors and to said active inverters, said control unit capable of causing each of said active inverters to regulate said DC current of said active inverters in accordance with said sensor information.

17. The electric power-generating device of claim 16 wherein said control unit brings each generator online sequentially in low fluid-flow conditions to improve system efficiency at low power.

18. The electric power-generating device of claim 17 wherein said control unit alternates the sequence in which said control unit shifts the order in which said generators are brought online such that each generator receives similar utilization.

19. A fluid-flow farm comprising:

a plurality of fluid-flow turbines each of which includes a synchronous generator coupled to a rectifier and an inverter, an output of said inverter being connected to a transformer, wherein reactive power control is fixed at said output of said inverter so that power factor is unity or set to provide a leading power factor that compensates for VAR of said transformer;

an electrical collection system electrically connected to each of said fluid-flow turbines, said electrical collection system having an output, which is an aggregate output of said fluid-flow farm, said output being connected to a substations wherein said electrical collection system is sized for operation of said fluid-flow turbines at unity power factor; and

,

a dynamically adjustable power factor controller at said substation for adjusting the power factor of said aggregate output of said fluid-flow farm.

20. A fluid-flow farm comprising:

a plurality of fluid-flow turbines each of which includes one or more synchronous generators, each coupled to a rectifier and an inverter, an output of said inverter being connected to a transformer, wherein VAR control is fixed at said output of said inverter such that a VAR load is set between and a leading power factor to compensate for the VAR of said external transformer and unity power factor, inclusive;

each one of said fluid-flow turbines comprising a blade which converts fluid-flow power into mechanical power, said one or more synchronous generators being selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said synchronous generators being operatively connected to said blade;

an electrical collection system electrically connected to each of said fluid-flow turbines and to a substation, wherein said electrical collection system is sized for operation of said fluid-flow turbines at unity power factor; and

,

a dynamically adjustable power factor controller at said substation for adjusting the power factor of the aggregate output of said fluid-flow farm.

21. An apparatus for generating electric power comprising:

first means for converting fluid-flow power into rotational mechanical power;

sensor means for providing sensor information;

a plurality of synchronous generators selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said synchronous generator being connected to said first means for converting said mechanical power into AC electrical power;

rectifying means connected to said plurality of generators for rectifying outputs of said generators to thereby convert said AC electrical power of said generators into DC electrical power;

inverting means connected to said rectifying means for inverting said DC electrical power to thereby convert said DC electrical power to AC electrical power said inverting means being capable of regulating DC electrical current; and

,

control means connected to said sensing means and to said inverting means, for causing said inverting means to regulate said DC electrical current in accordance with variations in said sensor information.

22. The apparatus of claim 21 further comprising:

further means in said control means for bringing each of said generators online sequentially in low fluid-flow conditions to improve system efficiency at low power.

23. The apparatus of claim 22 wherein the order in which said generators are brought online is such that each generator receives similar utilization.

24. An apparatus for generating electric power comprising:

a transformer;

a plurality of fluid-flow turbines, each of which includes a synchronous generator coupled to a rectifier and an inverter, an output of said inverter being connected to said transformer, wherein reactive power control is fixed at said output of said inverter so that power factor is unity or set to provide a leading power factor that compensates for VAR of said transformer;

a substation;

an electrical collection system electrically connecting each of said fluid-flow turbines to said substation;

said electrical collection system being sized for operation of said fluid-flow turbines at unity power factor; and

means at said substation for dynamically adjusting the power factor of the aggregate output of said plurality of fluid-flow turbines.

25. A apparatus for generating electric power comprising:

a plurality of fluid-flow turbines, each of which utilizing a blade to drive synchronous generators selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said synchronous generators converting fluid-flow power into AC electrical power at unity power factor;

converting means associated with each turbine for converting said AC electrical power of said synchronous generators into DC electrical power;

means for inverting said DC electrical power of each said synchronous generators of a turbine to thereby convert said DC electrical power to AC electrical power;

an electrical collection system for electrically connecting each of said fluid-flow turbines to a substation wherein said electrical collection system is sized for operation of said fluid-flow turbines at unity power factor; and

,

means for dynamically adjusting the power factor of the aggregate output of said plurality of fluid-flow turbines at said substation.

26. The apparatus of claim 25 further comprising:

a number of towers, one for each of said plurality of turbines;

each turbine and an associated converting means being located on top of one of said towers; and

,

said means for inverting being located at a bottom of said tower.

27. The apparatus of claim 26 further comprising:

means for conducting DC electrical power from said converting means at said top of said tower to said inverting means at said bottom of said tower.

28. A method of generating electric power comprising steps of:

A. converting fluid-flow power into mechanical power;

B. providing sensor information;

C. utilizing a plurality of generators selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators to convert said mechanical power into AC electrical power;

D. rectifying outputs of said generators to thereby convert said AC electrical power of said generators into DC electrical power;

E. inverting said DC electrical power at an inverter to thereby convert said DC electrical power to AC electrical power; and

,

F. regulating DC electrical current at said inverter in accordance with variations in said sensor information.

29. The method of claim 28 further comprising a step of:

E. bringing each of said generators online sequentially in low fluid-flow conditions to improve system efficiency at low power.

30. The method of claim 29 wherein in said step E the order in which said generators are brought online is such that each generator receives similar utilization.

31. A method of generating electric power comprising steps of:

A. providing a plurality of fluid-flow turbines that include synchronous generators selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said generators converting fluid-flow power into AC electrical power at a power factor fixed between a leading power factor to compensate for the VAR of an external transformer and a unity power factor, inclusive;

B. electrically connecting each of said fluid-flow turbines via an electrical collection system to a substation wherein said electrical collection system is sized for operation of said fluid-flow turbines at unity power factor; and

C. dynamically adjusting the power factor of the aggregate output of said plurality of fluid-flow turbines at said substation.

32. A method of generating electric power comprising steps of:

A. providing a plurality of fluid-flow turbines, each of which utilizing a blade to drive synchronous generators selected from a group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators, said generators converting fluid-flow power into AC electrical power at unity power factor;

B. rectifying outputs of each said synchronous generators of a turbine to thereby convert said AC electrical power of said synchronous generators into DC electrical power;

C. inverting said DC electrical power of each said synchronous generators of a turbine to thereby convert said DC electrical power to AC electrical power;

D. electrically connecting each of said fluid-flow turbines via an electrical collection system to a substation wherein said electrical collection system is sized for operation of said fluid-flow turbines at unity power factor; and

,

E. dynamically adjusting the power factor of the aggregate output of said plurality of fluid-flow turbines at said substation.

33. The method of claim 32 wherein:

said step A of providing a plurality of fluid-flow turbines includes the step of providing a plurality of towers with each one of said turbines on top of one of said towers;

said step B of rectifying outputs of each said generators is performed at said top of said one tower; and

,

said step C of inverting said DC electrical power of each said synchronous generators of a turbine to thereby convert said DC electrical power to AC electrical power is performed at a bottom of said one tower.

34. The method of claim 33 further comprising a step of:

F. conducting DC electrical power from said top of one tower to said bottom of said one tower prior to said step C of inverting said DC electrical power of each said synchronous generators of a turbine.

35. A variable speed wind turbine comprising:

a turbine rotor including at least one blade mounted on a rotatable shaft;

a synchronous generator selected from the group consisting of wound field synchronous generators wherein an exciter field is excited with a constant current and permanent magnet synchronous generators,

said synchronous generator being coupled to said turbine shaft for rotation therewith;

a sensor, an output of which is sensor information;

a power converter including an active inverter having switches that can be activated in response to inverter current commands in such a way as to vary DC current for phases of said generator; and

,

a controller coupled to said sensor and to said inverter, an output of said controller being an inverter current command related to required generator torque.

36. The apparatus of claim 35 wherein:

said inverter current command commands required generator torque based on rotor speed and power output of said inverter.