System and method for reducing voltage distortion from an inverter-based resource

1. A method for operating an inverter-based resource connected to a power grid, the method comprising:

receiving one or more voltage feedback signals created by at least one component of the inverter-based resource;

extracting a distortion component of the one or more feedback signals having a certain phase sequence and frequency by:

determining an angle representing a time-varying angular position of the certain phase sequence and frequency associated with the distortion component; and

rotating the one or more voltage feedback signals from a first reference frame by the angle to obtain a signal, wherein a steady component of the signal represents one or more vector components of the distortion component;

wherein the distortion component comprises any component of the one or more voltage feedback signals that is different from a positive-sequence, fundamental-frequency component of the one or more voltage feedback signals;

determining a voltage command for the power converter as a function of, at least, the distortion component; and,

controlling the power converter based on the voltage command such that voltage distortion created by the at least one component of the inverter-based resource is reduced in a manner that is relatively insensitive to voltage distortion created by sources external to the inverter-based resource.

2. The method of claim 1 , wherein the inverter-based resource comprises a dual-fed asynchronous generator (DFAG).

3. The method of claim 2 , wherein the at least one component of the inverter-based resource comprises at least one of a rotor-side converter or a line-side converter of the DFAG.

4. The method of claim 1 , wherein the inverter-based resource comprises at least one of a full-conversion wind generating system, a solar generation system, or an energy storage power system.

5. The method of claim 1 , wherein extracting the distortion component of the one or more voltage feedback signals further comprises:

filtering the rotated signal to attenuate components unrelated to the distortion component to isolate the distortion component.

6. The method of claim 5 , wherein extracting the distortion component of the one or more voltage feedback signals further comprises:

regulating, via a regulator, the rotated signal with a gain that sets a bandwidth thereof; and

rotating an output from the regulator back to the first reference frame to obtain the voltage command.

7. The method of claim 6 , wherein the regulator further comprises non-windup control comprising phase-preserving limit logic that maintains proportionality of the output signals.

8. The method of claim 7 , wherein the at least one component of the inverter-based resource comprises a rotor-side converter, the phase-preserving limit logic of the rotor-side converter is based on rotor speed.

9. The method of claim 6 , further comprising determining the voltage command for the power converter as a function of, at least, the distortion component for multiple control paths.

10. The method of claim 9 , wherein determining the voltage command for the power converter as a function of, at least, the distortion reduction signal further comprises:

adding the voltage commands from the multiple control paths together to obtain a trim signal.

11. The method of claim 10 , wherein determining the voltage command for the power converter as a function of, at least, the distortion reduction signal further comprises:

rotating the trim signal to a reference frame to combine with other control signals to obtain the voltage command.

12. A power system connected to a power grid, the power system comprising:

a dual-fed asynchronous generator (DFAG) comprising a rotor and a stator;

a power converter; and,

a controller for controlling the power system, the controller configured to perform a plurality of operations, the plurality of operations comprising:

receiving one or more voltage feedback signals created by at least one component of the power system;

extracting a distortion component of the one or more voltage feedback signals having a certain phase sequence and frequency by:

determining an angle representing a time-varying angular position of the certain phase sequence and frequency associated with the distortion component; and

rotating the one or more voltage feedback signals from a first reference frame by the angle to obtain a signal wherein a steady component of the signal represents vector components of the distortion component;

wherein the distortion component comprises any component of the one or more voltage feedback signals that is different from a positive-sequence, fundamental-frequency component of the one or more voltage feedback signals;

determining a voltage command for the power converter as a function of, at least, the distortion component; and,

controlling the power converter based on the voltage command such that voltage distortion created by the at least one component of the DFAG is reduced in a manner that is relatively insensitive to voltage distortion created by sources external to the DFAG.

13. The power system of claim 12 , wherein the at least one component of the DFAG power system comprises at least one or the rotor-side converter or the line-side converter.

14. The power system of claim 12 , wherein extracting the distortion component of the one or more voltage feedback signals further comprises

filtering the rotated signal to attenuate components unrelated to the distortion component to isolate the distortion component.

15. The power system of claim 14 , wherein extracting the distortion component of the one or more feedback signals further comprises:

regulating, via a regulator, the rotated signal with a gain that sets a bandwidth thereof; and

rotating an output from the regulator back to the first reference frame to obtain the voltage command.

16. The power system of claim 15 , further comprising determining the voltage command for the power converter as a function of, at least, the distortion component for multiple control paths.

17. The power system of claim 15 , wherein the regulator further comprises non-windup control comprising phase-preserving limit logic that maintains proportionality of the output signals.

18. The power system of claim 17 , wherein determining the voltage command for the power converter as a function of, at least, the distortion reduction signal further comprises:

adding the voltage commands from the multiple control paths together to obtain a trim signal.

19. The power system of claim 18 , wherein determining the voltage command for the power converter as a function of, at least, the distortion reduction signal further comprises:

rotating the trim signal to a reference frame to combine with other control signals to obtain the voltage command.