Load alignment assistance during startup of synchronous grid

Patent metadata

Field	Value
Publication number	US-10622813-B2
Application number	US-201615366555-A
Country	US
Kind code	B2
Filing date	Dec 1, 2016
Priority date	Aug 4, 2016
Publication date	Apr 14, 2020
Grant date	Apr 14, 2020

Abstract

Methods and systems for load alignment assistance are provided. An alignment current may be provided with a partial power converter through an n-phase supply line to a synchronous alternating current (AC) motor during a startup of a synchronous AC grid. The synchronous AC motor may receive polyphase AC power through the n-phase supply line from the synchronous AC grid during the startup. The partial power converter may be powered by a power source isolated from the synchronous AC grid. The alignment current may be controlled such that the alignment current causes a rotor of the synchronous AC motor to align with a rotor of a generator that powers the synchronous AC grid.

First claim

What is claimed is:

1. An apparatus for load alignment assistance, the apparatus comprising:
a partial power converter configured to provide an alignment current through an n-phase supply line to a synchronous alternating current (AC) motor during a startup of the synchronous AC motor, wherein the synchronous AC motor receives polyphase AC power through the n-phase supply line from a synchronous AC grid during the startup, and wherein the partial power converter is powered by a power source isolated from the synchronous AC grid; and
a controller configured to direct the partial power converter to provide the alignment current through the n-phase supply line, wherein the alignment current is selected to cause a rotor of the synchronous AC motor to align with a rotor of a generator that powers the synchronous AC grid.

2. The apparatus of claim 1 wherein the controller is configured to select a current vector angle of the alignment current that matches a generator rotor position of the generator.

3. The apparatus of claim 1 wherein the controller is configured to set a magnitude of the alignment current to a predetermined value.

4. The apparatus of claim 1 wherein the controller is configured to set a magnitude of the alignment current to a value large enough to cause mechanical torque on the rotor of the generator that overcomes any mechanical forces acting against rotation of the rotor of the motor.

5. The apparatus of claim 1 wherein the controller is configured to determine a magnitude of the alignment current based on inertia of the rotor of the motor.

6. The apparatus of claim 1 , wherein the controller is configured to determine a magnitude of the alignment current based on a difference between a motor rotor position and a generator rotor position.

7. A method for load alignment assistance, the method comprising:
providing an alignment current with a partial power converter through an n-phase supply line to a synchronous alternating current (AC) motor during a startup of a synchronous AC grid, wherein the synchronous AC motor receives polyphase AC power through the n-phase supply line from the synchronous AC grid during the startup, and wherein the partial power converter is powered by a power source isolated from the synchronous AC grid; and
controlling the alignment current such that the alignment current causes a rotor of the synchronous AC motor to align with a rotor of a generator that powers the synchronous AC grid.

8. The method of claim 7 wherein controlling the alignment current comprises setting a current vector angle of the alignment current to match a generator rotor position of the generator.

9. The method of claim 7 wherein controlling the alignment current comprises setting a magnitude of the alignment current to a predetermined value.

10. The method of claim 7 wherein controlling the alignment current comprises setting a magnitude of the alignment current to a value large enough to cause mechanical torque on the rotor of the generator that overcomes any mechanical forces acting against rotation of the rotor of the motor.

11. The method of claim 7 wherein controlling the alignment current comprises setting a magnitude of the alignment current based on inertia of the rotor of the motor.

12. The method of claim 7 , wherein controlling the alignment current comprises setting a magnitude of the alignment current based on a difference between a motor rotor position and a generator rotor position.

13. The method of claim 7 wherein controlling the alignment current comprises determining an amount of torque needed to achieve a desired rate of acceleration, and determining a magnitude of the alignment current from the determined amount of torque.

14. The method of claim 7 wherein controlling the alignment current comprises selecting a current vector angle of the alignment current that matches a generator rotor position of the generator, and determining a magnitude of the alignment current, wherein the current vector angle dictates relative amplitudes of components of the alignment current provided to the phases of the n-phase supply line.

15. A system comprising:
a partial power converter configured to provide an alignment current through an n-phase supply line to a synchronous alternating current (AC) motor, wherein the synchronous AC motor is configured to receive polyphase AC power through the n-phase supply line from a synchronous AC grid, and wherein the partial power converter is powered by a power source isolated from the synchronous AC grid; and
a controller configured to direct the partial power converter to provide the alignment current through the n-phase supply line, wherein the alignment current is selectively applied to cause a rotor of the synchronous AC motor to align with a rotor of a generator that powers the synchronous AC grid, the current selectively applied as the rotor of the generator rotates.

16. The system of claim 15 wherein the controller is configured to select a current vector angle of the alignment current that matches a generator rotor position of the generator and set a magnitude of the alignment current, wherein the current vector angle dictates relative amplitudes of components of the alignment current provided to the phases of the n-phase supply line.

17. The system of claim 15 wherein the controller is configured to set a magnitude of the alignment current to a predetermined value until the rotor of the synchronous AC motor is aligned with the rotor of the generator.

18. The system of claim 15 wherein the controller is configured to set a magnitude of the alignment current to a value large enough to cause mechanical torque on the rotor of the generator that overcomes any mechanical forces acting against rotation of the rotor of the motor.

19. The system of claim 15 wherein the controller is configured to determine a magnitude of the alignment current based on inertia of the rotor of the motor.

20. The system of claim 15 , wherein the controller is configured to determine a magnitude of the alignment current based on a difference between a motor rotor position and a generator rotor position.

Assignees

• Rolls Royce Nam Tech Inc

Inventors

• Blackwelder Mark Jon
• Rancuret Paul M

Classifications

• H02P1/46 Primary

  for starting an individual synchronous motor {(H02P27/04 takes precedence)} · CPC title

• H02P9/00

  Arrangements for controlling electric generators for the purpose of obtaining a desired output · CPC title

• H02P11/06

  for controlling dynamo-electric converters having an AC output · CPC title

• H02J3/40 Primary

  Synchronisation of generators for connection to a network or to another generator · CPC title