Using distributed power electronics-based devices to improve the voltage and frequency stability of distribution systems

1. A method, comprising:

in response to a line frequency variation of a power grid, adjusting a voltage setpoint of a voltage regulator coupled to the power grid at a grid edge to maintain a voltage at the grid edge, wherein the adjusting the regulated voltage setpoint is configured to reduce the line frequency variation to stabilize the line frequency of the power grid.

2. The method of claim 1 , further comprising adjusting a voltage setpoint of one or more other voltage regulators in response to the same line frequency variation to reduce the line frequency variation to stabilize the line frequency of the power grid through the aggregate effect of adjusting the voltage setpoints of the voltage regulators.

3. The method of claim 1 , further comprising identifying the frequency variation from a line frequency signal.

4. The method of claim 3 , further comprising detecting the line frequency to produce the line frequency signal.

5. The method of claim 1 , wherein the adjusting the voltage setpoint in response to the line frequency variation comprises adjusting the voltage setpoint in response to the line frequency variation passing one or more predetermined line frequency thresholds.

6. The method of claim 1 , wherein the adjusting the voltage setpoint in response to the line frequency variation comprises adjusting the voltage setpoint according to a predetermined variation in the voltage setpoint over time.

7. The method of claim 1 , wherein the adjusting the voltage setpoint in response to the line frequency variation comprises controlling to a line frequency setpoint through adjusting of the voltage setpoint as a process variable.

8. The method of claim 1 , further comprising estimating a grid inertia based on characteristics of the frequency variation and updating based on the estimate a voltage setpoint adjustment to be used in response to a future frequency variation.

9. The method of claim 1 , further comprising comparing characteristics of the frequency variation to a desired reduction in frequency variation and updating based on the comparison a voltage setpoint adjustment to be used in response to a future frequency variation.

10. The method of claim 1 , wherein the voltage regulator comprises a series compensator configured to maintain voltage at a secondary side of the voltage regulator.

11. The method of claim 10 , wherein the series compensator comprises a dynamic voltage restorer.

12. The method of claim 1 , wherein the voltage regulator comprises a shunt compensator configured to maintain a grid voltage at a primary side of the voltage regulator.

13. The method of claim 1 , wherein the adjusting the voltage setpoint in response to the line frequency variation is performed independent of an external command communication.

14. An apparatus, comprising:

a voltage regulator configured to couple to a power grid at a grid edge and to maintain a voltage at the grid edge, wherein the voltage regulator is further configured to adjust a voltage setpoint of a voltage regulator in response to a line frequency variation of the power grid to reduce the line frequency variation and stabilize the line frequency of the power grid.

15. The apparatus of claim 14 , further comprising one or more other voltage regulators configured to adjust respective voltage setpoints in response to the same line frequency variation to reduce the line frequency variation and stabilize the line frequency of the power grid through the aggregate effect of adjusting the voltage setpoints of the voltage regulators.

16. The apparatus of claim 14 , wherein the voltage regulator is configured to identify the frequency variation from a line frequency signal.

17. The apparatus of claim 16 , wherein the voltage regulator comprises a line frequency detector configured to detect a frequency of a power grid voltage coupled to the voltage regulator and to produce the line frequency signal corresponding to the detected frequency.

18. The apparatus of claim 14 , wherein the voltage regulator is configured to adjust the voltage setpoint in response to the line frequency variation passing one or more predetermined line frequency thresholds.

19. The apparatus of claim 14 , wherein the voltage regulator is configured to adjust the voltage setpoint in response to the line frequency variation by adjusting the voltage setpoint according to a predetermined variation in the voltage setpoint over time.

20. The apparatus of claim 14 , wherein the voltage regulator is configured to adjust the voltage setpoint in response to the line frequency variation by controlling to a line frequency setpoint through adjustment of the voltage setpoint as a process variable.

21. The apparatus of claim 14 , wherein the voltage regulator is configured to estimate a grid inertia based on characteristics of the frequency variation and updating based on the estimate a voltage setpoint adjustment to be used in response to a future frequency variation.

22. The apparatus of claim 14 , wherein the voltage regulator is configured to compare characteristics of the frequency variation to a desired reduction in frequency variation and updating based on the comparison a voltage setpoint adjustment to be used in response to a future frequency variation.

23. The apparatus of claim 14 , wherein the voltage regulator comprises a series compensator configured to maintain voltage at a secondary side of the voltage regulator.

24. The apparatus of claim 23 , wherein the series compensator comprises a dynamic voltage restorer.

25. The apparatus of claim 14 , wherein the voltage regulator comprises a shunt compensator configured to maintain a grid voltage at a primary side of the voltage regulator.

26. The apparatus of claim 14 , wherein the voltage regulator is configured to adjust the voltage setpoint in response to the line frequency variation independent of an external command communication.

27. The apparatus of claim 14 , wherein the voltage regulator comprises:

a controller configured to generate a voltage control signal responsive to a variation in grid voltage and to generate a voltage setpoint adjustment signal in response to the frequency variation.

28. A power electronics device, comprising the voltage regulator of claim 14 .

29. A method of manufacturing an apparatus, the method comprising:

providing a controller for a voltage regulator at a power grid edge, the controller comprising a computer-readable storage device or memory storing computer executable instructions that when executed by a processor, cause the controller to perform a method of voltage and frequency regulation at the power grid edge, the method comprising:

receiving an indication of a line frequency variation in the power grid, and

adjusting a voltage setpoint of the voltage regulator to reduce the line frequency variation and stabilize the line frequency of the power grid.

30. The method of claim 29 , further comprising programming the controller by selecting one or more frequency variation thresholds for triggering the adjusting of the voltage setpoint.

31. The method of claim 29 , further comprising programming the controller to communicate with voltage regulators to coordinate simultaneous frequency regulation with shunt-based compensators.

32. The method of claim 29 , further comprising programming the controller to autonomously estimate a grid inertia based on characteristics of the frequency variation and autonomously update based on the estimate a voltage setpoint adjustment to be used in response to a future frequency variation.

33. The method of claim 29 , further comprising programming the controller to autonomously compare characteristics of the frequency variation to a desired reduction in frequency variation and autonomously update based on the comparison a voltage setpoint adjustment to be used in response to a future frequency variation.