Line impedance compensation system

• US 9,859,710 B2
• Filed: 10/03/2013
• Issued: 01/02/2018
• Est. Priority Date: 10/08/2012
• Status: Active Grant

• Current Assignee: Vestas Wind Systems A/S
• Original Assignee: Vestas Wind Systems A/S
• Inventors: Garcia, Jorge Martinez
• Primary Examiner(s): Houston, Adam
• Application Number:
  US14/434,290
• Publication Number:
  US 20150263521A1
• Time in Patent Office: 1,552 Days
• Field of Search: 307 52, 290 44
• CPC Class Codes: F03D 7/048 controlling wind farms
• CPC Class Codes: F03D 9/255 connected to electrical distribution networks; Arrangements therefor
• CPC Class Codes: H02J 2300/28 The renewable source being wind energy wind motors F03D
• CPC Class Codes: H02J 3/16 by adjustment of reactive power
• CPC Class Codes: H02J 3/18 Arrangements for adjusting, eliminating or compensating reactive power in networks for adjustment of voltage H02J3/16
• 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: 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

The present invention relates to a power plant controller (23), controlling at least one electrical parameter of a wind power plant at a first point (201), the power plant controller receiving at least one measured electrical parameter at a point of measurement (204a, b), the point of measurement being different from the first point, and estimating a delta value of a difference of the at least one electrical parameter between the first point and the point of measurement, wherein estimating of the delta value is calculated based on an impedance between the point of measurement and the first point, and at least one reference value of the power plant controller, and the power plant controller controls the at least one electrical parameter on the basis of the at least one measured electrical parameter and the delta value.

Claims

1. A power plant controller of a wind power plant comprising a plurality of wind turbine generators, the power plant controller configured to:

receive at least one measured electrical parameter at a point of measurement located at a first location on a grid coupled with the wind power plant, wherein the point of measurement is different from a first point located at a second location on the grid,

estimate a delta value of a difference of at least one electrical parameter between the first point and the point of measurement, wherein the delta value is based on an impedance between the point of measurement and the first point, and a reference value of the power plant controller, and

control the at least one electrical parameter based on the at least one measured electrical parameter and the delta value.

2. The power plant controller according to claim 1, wherein a value of the at least one electrical parameter at the first point is a summation of the at least one measured electrical parameter at the point of measurement and the delta value.

3. The power plant controller according to claim 1, wherein the grid comprises an internal grid and an external grid, wherein the plurality of wind turbine generators is connected to the internal grid, and wherein the wind power plant is connected to the external grid through a point of common coupling, and the first point is the point of common coupling, and the point of measurement is at the internal grid or at the external grid.

4. The power plant controller according to claim 1, wherein the electrical parameter is a voltage level, and wherein the at least one electrical input parameter is at least a voltage reference value and a current reference value.

5. The power plant controller according to claim 4, wherein the delta value of the voltage level is estimated according to the following equation:

6. The power plant controller according to claim 1, wherein the electrical parameter is reactive power, and wherein the reference value is at least a voltage reference value and a current reference value.

7. The power plant controller according to claim 6, wherein the delta value of the reactive power is estimated according to the following equation:

Δ

Q_s=(−

V_ref²Y+XI_ref²)·

l.

8. The power plant controller according to claim 1, wherein the at least one electrical parameter is a voltage, and wherein the delta value is derived as a subtraction between the voltage at the first point and the voltage at the point of measurement, multiplied with a predetermined slope function, wherein the predetermined slope function is a function of the impedance between the point of measurement and the first point, and a further multiplication with the voltage at the point of measurement, for hereby estimating a reactive power reference.

9. The power plant controller according to claim 8, wherein the reactive power reference is compensated according to the impedance between the point of measurement and the first point, by adding a compensation value.

10. The power plant controller according to claim 1, wherein the power plant controller calculates a reference set point for the plurality of wind turbine generators, and the power plant controller further comprises a dispatcher to dispatch electrical reference set points to each of the plurality of wind turbine generators.

11. The power plant controller according to claim 1, wherein the power plant controller further comprises at least one measuring device to measure the at least one measured electrical parameter at the point of measurement.

12. The power plant controller according to claim 1, wherein the power plant controller acts as a master controller for at least one local power plant controller, and the at least one local power plant controller controls a subset of the plurality of wind turbine generators.

13. A wind power plant arranged to be controlled by a power plant controller according to claim 1.

14. A method for controlling at least one electrical parameter of a wind power plant at a first point located at a first location on an electrical grid coupled with the wind power plant, wherein the wind power plant comprises a plurality of wind turbine generators, the method comprising:

receiving at least one measured electrical parameter at a point of measurement located at a second location on the electrical grid, wherein the point of measurement is different from the first point,

estimating a delta value of a difference of the at least one electrical parameter between the first point and the point of measurement, wherein the delta value is based on an impedance between the point of measurement and the first point, and a reference value of a power plant controller, and

controlling the at least one electrical parameter on based on the at least one measured electrical parameter and the delta value.

15. The method according to claim 14, wherein a value of the at least one electrical parameter at the first point is a summation of the at least one measured electrical parameter at the point of measurement and the delta value.

16. The method according to claim 14, wherein the electrical grid comprises an internal grid and an external grid, wherein the plurality of wind turbine generators is connected to the internal grid, and wherein the wind power plant is connected to the external grid through a point of common coupling, and the first point is the point of common coupling, and the point of measurement is at the internal grid or at the external grid.

17. The method according to claim 14, wherein the electrical parameter is a voltage level, and wherein the reference value is at least a voltage reference value and a current reference value.

18. The method according to claim 17, wherein the delta value of the voltage level is estimated according to the following equation:

19. The method according to claim 14, wherein the electrical parameter is reactive power, and wherein the reference value is at least a voltage reference value and a current reference value.

20. The method according to claim 19, wherein the delta value of the reactive power is estimated according to the following equation:

Δ

Q_s=(−

V_ref²Y+XI_ref²)·

l.