Fuzzy logic integrated electrical control to improve variable speed wind turbine efficiency and performance

• US 5,652,485 A
• Filed: 02/06/1995
• Issued: 07/29/1997
• Est. Priority Date: 02/06/1995
• Status: Expired due to Fees

• Current Assignee: United States Environmental Protection Agency
• Original Assignee: United States Environmental Protection Agency
• Inventors: Bose, Bimal K., Spiegel, Ronald J.
• Primary Examiner(s): Masih, Karen
• Application Number:
  US08/384,055
• Time in Patent Office: 904 Days
• Field of Search: 318/147, 318/151, 318/153, 318/157, 318/398-815, 318/113, 395/21, 395/900, 395/20, 322/28, 322/17, 322/29, 322/35, 322/44, 322/14, 290/55, 290/44, 388/804
• US Class Current: 318/147
• CPC Class Codes: F03D 7/0272 by measures acting on the electrical generator
• CPC Class Codes: F03D 7/046 with learning or adaptive control, e.g. self-tuning, fuzzy logic or neural network
• CPC Class Codes: F05B 2270/20 to optimise the performance of a machine
• CPC Class Codes: F05B 2270/322 the detection or prediction of a wind gust
• CPC Class Codes: F05B 2270/707 fuzzy logic
• CPC Class Codes: H02P 2101/15 for wind-driven turbines
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence
• CPC Class Codes: Y02E 10/72 Wind turbines with rotation axis in wind direction
• CPC Class Codes: Y10S 706/90 Fuzzy logic

Abstract

A control system utilizing fuzzy logic adaptive control to control the operation of a wind turbine driven electric power generator to control power generator speed and hence power frequency while maximizing the power output of the power generator. Wind turbulence effects are eliminated and airgap magnetic flux of the power generator is controlled.

Claims

1. An efficient wind turbine driven electric power generator fuzzy logic based control system to improve power efficiency of the generator comprising:

an induction operated generator including an air gap with magnetic flux;

a pulse width modulated control to vary an operating speed of said generator to maintain a substantially constant power frequency output from said generator;

fuzzy logic based controls to modify the operation of said pulse width modulated control to maximize the power output of said generator under variations of a wind driving said power generator;

the modification of said operation of said pulse width modulated control to maximize said power output including means to vary said airgap magnetic flux of said generator;

said generator being a squirrel cage induction generator; and

said pulse width modulated control including solid state insulated gate bipolar transistor power electronic rectifier-inverter combination enabling power to flow in either direction to enable said generator to operate as a motor to provide start-up torque for said wind turbine generator.

2. The wind driven fuzzy logic based control system of claim 1 wherein said fuzzy logic control system further includes a fuzzy logic adaptive controller to adjust the speed of a variable speed generator for maximization of power output;

said adaptive controller operating on feedback signals derived from the electric power output of said electric power generator without the need for any wind velocity data.

3. The improved wind driven fuzzy logic based control system of claim 2 wherein said fuzzy logic control system includes at least one fuzzy logic controller which controls a flux component of current of said generator to control said air gap magnetic flux to reduce a power losses of said generator to further maximize the power output of said generator.

4. An efficient wind driven turbine driven electric power generator fuzzy logic based control system to improve power efficiency of the generator comprising:

an induction operated generator including an air gap with magnetic flux;

a pulse width modulated control operating to vary a speed of said generator to maintain a substantially constant power frequency output from said generator;

fuzzy logic based controls to modify the operation of said pulse width modulated control to maximize a power output of said generator under variations of a wind driving said power generator;

the modification of said operation of said pulse width modulated control to maximize said power output including means to vary said airgap magnetic flux of said generator;

wherein said control system further includes at least one solid state converter to control the speed of said generator to maintain said substantially constant power frequency;

said fuzzy logic control system further includes a fuzzy logic adaptive controller to adjust the speed of said variable speed generator for maximization of power output;

said fuzzy logic control system includes at least one fuzzy logic controller which controls a flux component of current of said generator to further maximize the power output of said generator;

said at least one solid converter includes a pulse width modulator and said fuzzy logic control system provides an input to said pulse width modulator; and

wherein said fuzzy logic controller utilizes a fuzzy logic role base which is substantially;

space="preserve" listing-type="tabular">______________________________________Δ

P.sub.o \LΔ

N P______________________________________PB NB PBPM NM PMPS NS PSZE ZE ZENS PS NSNM PM NMNB PB NB______________________________________

wherein;

P_o =power output of generator

L.sub.Δ

=last change

S=small

B=big

N=negative

P=positive

Z=zero.

5. The wind driven fuzzy logic control system of claim 4 wherein said generator is an induction generator which also operates as an induction motor when supplied with input power to provide starting torque to initiate rotation of said wind turbine.

6. An efficient integrated intelligent adaptive controller for a variable speed electric power generator including an air gap with magnetic flux driven by a variable power source comprising:

said generator being a squirrel cage induction motor;

power detection means to detect an electrical output power of said electrical power generator;

means including fuzzy logic control means to maintain a required speed of said electrical power generator for substantially constant power frequency output substantially independent of wind turbulence effects;

means to determine an optimum operation of said electrical power generator which will provide improved efficiency; and

said fuzzy logic control means to vary said airgap magnetic flux of said electrical power generator in increments to modify said speed of said generator to further improve said efficiency;

said fuzzy logic control including a plurality of intelligent fuzzy logic controllers operating in response to signals derived from the power output of said electric power generator;

said fuzzy logic controllers providing a plurality of control signals;

one of said control signals varying a rotor speed of said generator to optimize a turbine aerodynamic efficiency for maximum power output; and

another of said control signals reducing a magnetizing component of a stator current of said generator to optimize said generator air gap magnetic flux to minimize power losses of said generator.

7. The improved integrated fuzzy logic control of claim 6 wherein said variable power Source is wind and a wind turbine is provided to rotate said generator in response to said wind.

8. The integrated fuzzy logic control of claim 7 wherein said at least one fuzzy logic controller utilizes a rule base which is substantially:

space="preserve" listing-type="tabular">______________________________________Δ

P.sub.o \LΔ

N P______________________________________PB NB PBPM NM PMPS NS PSZE ZE ZENS PS NSNM PM NMNB PB NB______________________________________

Wherein;

P₀ =power output of generator

LΔ

=last change

S=small

M=medium

B=big

N=negative

P=positive

Z=zero.

9. The integrated fuzzy logic control of claim 8 wherein said generator is an induction generator which can also operate as an induction motor when supplied with input power to provide starting torque to initiate rotation of said round turbine.

10. The integrated fuzzy logic control of claim 9 wherein the output of said generator is connected to a power grid, and said input power is provided by said power grid when said induction generator operates as an induction motor.

11. An efficient integrated intelligent controller for a variable speed generator including an air gap with magnetic flux driven by a variable power source comprising;

power detection means to detect a electrical output of said electrical power generator;

means to maintain a required speed of said electrical power generator substantially independent of wind turbulence effects;

means including fuzzy logic control means to determine the optimum operation of said electrical power generator which will provide improved efficiency; and

said fuzzy logic control means responsive to said power detection means to vary said airgap magnetic flux of said electrical power generator in increments to modify said speed of said generator to further improve said efficiency;

wherein said variable power source is wind and wind turbine is provided to rotate said generator in response to said wind;

said fuzzy logic control includes means to vary said airgap magnetic flux of said generator and at least one fuzzy logic controller to generate a flux control signal to vary said airgap flux;

said means to maintain the speed of said electrical power generator include solid state electronic converters; and

said fuzzy logic control further includes a second fuzzy logic controller to provide a signal for adjusting said variable speed generator for maximum power.

12. The improved integrated fuzzy logic control of claim 11 wherein said fuzzy logic control further includes a third fuzzy logic controller to provide a fuzzy logic based adaptive speed loop controller to substantially eliminate wind turbulence effects and maintain substantially constant frequency of the output electric power provided by said generator.

13. The integrated fuzzy logic control of claim 12 wherein said solid state converters include at least one pulse width modulated inverter and at least one pulse width modulated rectifier.

14. The integrated fuzzy logic control of claim 13 wherein said solid state converters include at least one insulated gate bipolar transistor connected in parallel with a rectifier and forming a converter element.

15. The integrated fuzzy logic control of claim 14 wherein a plurality of said converter elements are connected in parallel to handle increased electric power.

16. The integrated fuzzy logic control of claim 15 wherein said inverter and said rectifier are connected by a DC link including at least on filter capacitor.

17. The integrated fuzzy logic control of claim 13 wherein a first pulse width modulated controller is provided to control the operation of said pulse width modulated inverter, and a second pulse width modulated controller is provided to control the operation of said pulse width modulated rectifier.

18. The integrated fuzzy logic control of claim 17 wherein each of the pulse width modulated controllers receives control signals provided by the fuzzy logic flux controller and from said fuzzy logic adaptive speed loop controller.

19. The integrated fuzzy logic control of claim 18 wherein said first pulse width modulated controller receives a control signed provided by the fuzzy logic power output controller.

20. The integrated fuzzy logic control of claim 11 wherein said at least one fuzzy logic controller utilizes a rule base which is substantially:

space="preserve" listing-type="tabular">______________________________________Δ

Po\LΔ

W.sub.r P ZE N______________________________________PVB PVB PVB NVBPB PB PVB NBPM PM PB NMPS PS PM NSZE ZE ZE ZENS NS NM PSNM NM NB PMNB NB NVB PBNVB NVB NVB PVB______________________________________

wherein;

N is negative

P is positive

PVB is positive very big

PB is positive big

PM is positive medium

PS is positive small

ZE is zero

NS is negative small

NM is negative medium

NB is negative big

NVB is negative very big.

21. The improved integrated fuzzy logic control of claim 12 wherein said at least one fuzzy logic controller utilizes a rule base which is substantially:

space="preserve" listing-type="tabular">______________________________________E\CE NVL NL NM NS ZE PS PM PL PVL______________________________________NVL NVB NB NM NS ZENL NB NM NS ZE PSNM NB NM NS ZE PS PMNS NB NM NS ZE PS PM PBZE NB NM NS ZE PS PM PBPS NB NM NS ZE PS PM PBPM NM NB ZE PS PM PBPL NS ZE PM PM PBPVL ZE PS PM PB PVB______________________________________

wherein;

N is negative

P is positive

PVB is positive very big

PB is positive big

PM is positive medium

PS is positive small

ZE is zero

NS is negative small

NM is negative medium

NB is negative big

NVB is negative very big.