System and method for improved reactive power speed-of-response for a wind farm

Patent metadata

Field	Value
Publication number	US-9831810-B2
Application number	US-201514642869-A
Country	US
Kind code	B2
Filing date	Mar 10, 2015
Priority date	Mar 10, 2015
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

The present subject matter is directed to a system and method for regulating reactive power in a wind farm connected to a power grid so as to improve reactive speed-of-response of the wind farm. The method includes receiving a voltage feedback from the power grid and a voltage reference and calculating a linear voltage error as a function of the voltage feedback and the voltage reference. A further step includes generating a first output based on the linear voltage error via a first control path having a first voltage regulator. A further step includes determining a non-linear voltage error based on the linear voltage error via a second control path having a second voltage regulator. A second output is generated via the second control path based on the non-linear voltage error. As such, a reactive power command is generated as a function of the first and second outputs.

First claim

What is claimed is:

1. A method for improving reactive power speed-of-response in a wind farm connected to a power grid, the method comprising:
receiving, by a wind farm controller, a voltage feedback from the power grid;
receiving, by the wind farm controller, a voltage reference;
calculating a linear voltage error as a function of the voltage feedback and the voltage reference;
generating a first output based on the linear voltage error via a first control path having a first voltage regulator;
determining a first non-linear voltage error based on the linear voltage error via a deadband of a second voltage regulator of a second control path;
generating, via the second control path, a second output based on the first non-linear voltage error; and,
generating a reactive power command as a function of the first and second outputs.

2. The method of claim 1 , further comprising determining a second non-linear voltage error based on the linear voltage error via a transient amplifier.

3. The method of claim 1 , wherein the first voltage regulator comprises a proportional integral controller and the second voltage regulator comprises a proportional controller.

4. The method of claim 1 , further comprising adjusting a time constant of the second voltage regulator so as to stabilize the second output of the second control path.

5. The method of claim 1 , further comprising limiting the first voltage regulator based on predetermined integral limits and limiting the reactive power command based on predetermined command limits, wherein the predetermined command limits are greater than the predetermined integral limits.

6. The method of claim 1 , wherein the first voltage regulator is associated with a first state variable and the second voltage regulator is associated with one or more second state variables, and the method further comprises determining a derivative of one or more of the one or more second state variables.

7. The method of claim 6 , further comprising maintaining the first state variable and the one or more second state variables at their present values for as long as the derivative of one or more of the second state variables is negative, one or more of the second state variables is negative, and the first or second non-linear voltage errors is negative.

8. The method of claim 7 , further comprising maintaining the first and second state variables at their present values for as long as the derivative of the second state variable is negative, the second state variable is positive, and the first or second non-linear voltage errors is positive.

9. The method of claim 6 , further comprising maintaining the first state variable and the one or more second state variables at their present values for as long as the voltage feedback is outside of a predetermined voltage range.

10. The method of claim 1 , further comprising determining one or more voltage regulator parameters for the first and second voltage regulators, wherein the voltage regulator parameters comprise at least one of proportional gains, integral gains, or time constants.

11. The method of claim 10 , further comprising varying the voltage regulator parameters based on at least one of a number of online wind turbines in the wind farm or a status of one or more external devices to the wind farm.

12. A method for regulating reactive power in a power system connected to a power grid, the method comprising:
determining, via a non-linear voltage regulator, a non-linear voltage error as a function of a linear voltage error;
calculating a non-linear time constant as a function of at least one of the non-linear voltage error or history of the non-linear voltage regulator;
adjusting the non-linear time constant; and,
determining an output of the non-linear voltage regulator based on the non-linear voltage error, a non-linear gain parameter, and the non-linear time constant.

13. A voltage control system, comprising:
a first control path comprising a first voltage regulator, the first control path configured to calculate a linear voltage error as a function of at least one of a voltage feedback or a voltage reference and generate a first output based on the linear voltage error; and,
a second control path comprising a second voltage regulator, the second voltage regulator comprising a deadband configured to determine a first non-linear voltage error based on the linear voltage error, the second voltage regulator configured to generate a second output based on the non-linear voltage error,
wherein the voltage control system is further configured to generate a reactive power command as a function of the first and second outputs.

14. The voltage control system of claim 13 , wherein the second voltage regulator further comprises a transient amplifier configured to generate a second non-linear voltage error so as to amplify voltage changes in a power grid.

15. The voltage control system of claim 13 , wherein the second voltage regulator is associated with at least one non-linear time constant, and wherein the second voltage regulator is configured to adjust the at least one non-linear time constant so as to stabilize the second output of the second control path.

16. The voltage control system of claim 13 , wherein the first voltage regulator is associated with a first state variable and the second voltage regulator is associated with one or more second state variables, wherein the second voltage regulator is configured to determine a derivative of one or more of the second state variables and maintain the first state variable and the one or more second state variables at their present values for as long as the derivative of the one or more of the second state variables is negative, one or more of the second state variables is negative, and the first or second non-linear voltage errors is negative.

17. The voltage control system of claim 16 , wherein the second voltage regulator is configured to maintain the first state variable and the one or more second state variables at their present values if the derivative of one or more of the second state variables is negative, one or more of the second state variables is positive, and the first and second non-linear voltage error is positive.

18. The voltage control system of claim 13 , wherein the second voltage regulator is configured to maintain the first state variable and the one or more second state variables at their present values for as long as the voltage feedback is outside of a predetermined voltage range.

19. The voltage control system of claim 13 , wherein the voltage control system is configured to determine one or more voltage regulator parameters for the first and second voltage regulators and vary the voltage regulator parameters based on at least one of a number of online wind turbines in the wind farm or a status of one or more external devices to the wind farm, wherein the voltage regulator parameters comprise at least one of proportional gains, integral gains, or time constants.

Assignees

• Gen Electric

Inventors

• Achilles Alfredo Sebastian
• Larsen Einar Vaughn

Classifications

• F03D9/257

  the wind motor being part of a wind farm · CPC title

• H02J3/1842

  having reactive elements actively controlled by bridge converters, e.g. active filters or static compensators [STATCOM] · CPC title

• H02P2103/20

  of the synchronous type · CPC title

• H02P2101/15

  for wind-driven turbines · CPC title

• H02J2101/28

  Wind energy · CPC title