Voltage control for wind generators

• US 20050046196A1
• Filed: 09/03/2003
• Published: 03/03/2005
• Est. Priority Date: 09/03/2003
• Status: Active Grant

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Larsen, Einar V.
• Granted Patent: US 7,119,452 B2
• Time in Patent Office: Days
• US Class Current: 290/44
• CPC Class Codes: F03D 9/257 the wind motor being part of a wind farm
• CPC Class Codes: F05B 2260/96 Preventing, counteracting or reducing vibration or noise
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 2310/18 The network being internal to a power source or plant
• CPC Class Codes: H02J 3/16 by adjustment of reactive power
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02J 3/48 Controlling the sharing of the in-phase component
• CPC Class Codes: H02J 3/50 Controlling the sharing of the out-of-phase component
• 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
• CPC Class Codes: Y02E 40/30 Reactive power compensation

Abstract

A wind turbine generator control system includes relatively fast regulation of voltage near the individual generators with relatively slower overall reactive power regulation at a substation or wind farm level. The setpoint of the relatively fast voltage regulator is adjusted by the relatively slow reactive power regulator. The fast voltage regulation can be at the generator terminals or at a synthesized remote point.

Claims

1. A wind turbine generator control system comprising:

a reactive power regulator to control reactive power production by the wind turbine generator by adjusting voltage setpoint to a voltage regulator, the reactive power regulator having a first time constant; and

a voltage regulator coupled with the reactive power controller to control real power production by one or more wind turbine generators, the voltage regulator having a second time constant, wherein the first time constant is numerically greater than the second time constant.

2. The wind turbine generator control system of claim 1 wherein the first time constant is greater than one second.

3. The wind turbine generator control system of claim 1 wherein an input signal to the reactive power regulator comprises an error signal indicating a difference between a command limited to a predetermined range and a signal indicating measured reactive power.

4. The wind turbine generator control system of claim 3 wherein the predetermined range is defined by upper and lower limits based on generator reactive power capacity.

5. The wind turbine generator control system of claim 1 wherein an output signal from the reactive power regulator is limited to a predetermined range.

6. The wind turbine generator control system of claim 5 wherein the predetermined range is defined by upper and lower limits based on generator terminal voltage.

7. The wind turbine generator control system of claim 6 wherein the lower limit comprises approximately 95% of steady-state rated generator voltage and the upper limit comprises approximately 105% of steady-state rated generator voltage.

8. The wind turbine generator control system of claim 1 wherein an input signal to the voltage regulator comprises an error signal indicating a difference between an output signal from the reactive power regulator limited to a predetermined range and a signal indicating measured terminal voltage.

9. The wind turbine generator system of claim 8 wherein the predetermined range is defined by an upper and a lower limit based on converter ratings and/or operating set points.

10. The wind turbine generator system of claim 8 wherein an output signal from the voltage regulator comprises a current command to a generator exciter.

11. The wind turbine generator system of claim 8 wherein an output signal from the voltage regulator determines a current to be supplied to the generator.

12. A method comprising:

receiving a reactive power command;

determining a voltage set point based on the reactive power command, wherein the voltage set point is limited to a range of upper and lower limits based on generator terminal voltage;

determining a rotor current command for the wind turbine generator in response to the voltage setpoint, wherein the rotor current command is limited to a range based on a current rating of the wind turbine generator and a contemporaneous real power output;

transmitting the rotor current command to a rotor controller of the wind turbine generator; and

generating a real and reactive power based on the rotor current command.

13. The method of claim 12 wherein the voltage set point based on the reactive power command is determined by a reactive power regulator.

14. The method of claim 12 wherein a voltage set point based on the reactive power command comprises generating, with a reactive power regulator, a voltage set point to be transmitted to a voltage regulator.

15. The method of claim 14 wherein the time constant of the voltage regulator is numerically less than the time constant of the reactive power regulator.

16. The method of claim 12 wherein receiving the reactive power command comprises receiving a farm level reactive power command from a farm level controller that transmits reactive power commands to multiple wind turbine generators.

17. The method of claim 12 wherein receiving the reactive power command comprises receiving a reactive power command locally from a source providing a reactive power command for a single wind turbine generator.

18. The method of claim 12 wherein the lower limit comprises approximately 95% of steady-state rated generator voltage and the upper limit comprises approximately 105% of steady-state rated generator voltage.

19. A method comprising:

receiving a reactive power command for a wind turbine generator;

limiting the reactive power command to a predetermined reactive power range to generate a limited reactive power signal;

generating a reactive power error signal based on a measured reactive power and the limited reactive power signal;

generating a voltage command based on the reactive power error signal, wherein the voltage command is limited to a predetermined voltage range;

generating a voltage error signal based on a measured voltage and the voltage command; and

generating a current command based on the current error signal, wherein the current command is limited to a predetermined current range, and a contemporaneous power output.

20. The method of claim 19 wherein the voltage error signal corresponds to a difference between the measured reactive power and the limited reactive power signal.

21. The method of claim 19 wherein the current error signal corresponds to a difference between a measured terminal voltage and the voltage command.

22. The method of claim 19 wherein the voltage command is generated by a reactive power regulator in a wind turbine generator and further wherein the reactive power regulator comprises a proportional integral (PI) controller having a time constant in the range of 1 to 10 seconds.

23. The method of claim 19 wherein the current command is generated by a voltage regulator in a wind turbine generator and further wherein the voltage regulator comprises a proportional integral (PI) controller having a time constant in the range of less than 2 seconds.