Control system for doubly fed induction generator
AssigneeXantrex Technology Inc.
InventorRaymond M. Hudson
Life of this patent
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Abstract
A controller (28) for a doubly fed induction generator (12,20) adjusts control signals to a rotor side converter (24) and line side converter (22) to adjust rotor current when a voltage transient on a utility grid (10) occurs, so that the doubly fed induction generator can ride through the transient. The controller can also turn off the transistors of the rotor side converter (24) to reduce rotor current and/or activate a crowbar (42) to reduce the voltage of the DC link (26) connecting the converters (22, 24) when significant voltage transients occur on the grid (10). This permits continued operation of the DFIG system without disconnecting from the grid.
Claims25
A method of controlling a doubly fed induction generator (DFIG) system, such DFIG system having a generator with a stator energized by a grid having a voltage with a nominal value, a driven rotor coupled with the stator, a grid side converter electrically connected to the grid, a rotor side converter electrically connected to the rotor, a DC link connecting the converters, a controller supplying control signals to the converters for control of the torque and reactive power from the DFIG system, which method comprises:
- providing rotor current command signals from the controller;
- monitoring the voltage of the grid for transients from nominal;
- and
- if a transient greater than a first predetermined transient occurs, adjusting the rotor current command signals to permit continued operation of the DFIG system without disconnecting the DFIG from the grid.
A method of controlling a doubly fed induction generator (DFIG) system, such DFIG system having a generator with a stator energized by a grid having a voltage with a nominal value, a driven rotor coupled with the stator, a grid side converter electrically connected to the grid, a rotor side converter electrically connected to the rotor, a DC link connecting the converters, a controller supplying control signals to the converters for control of the torque and reactive power from the DFIG system, which method comprises:
- monitoring the voltage of the grid for transients from nominal;
- and
- if a grid transient greater than a predetermined transient occurs, activating a crowbar to reduce the voltage of the DC link connecting the converters, without disconnecting the DFIG system from the grid.
A method of controlling a DFIG system, such DFIG system having a generator with a stator energized by an AC utility grid having a voltage with a nominal value, a variable speed wind driven rotor coupled with the stator, a grid side AC-DC converter electrically connected to the grid at the AC side, a rotor side AC-DC converter electrically connected to the rotor at the AC side, a DC link connecting the DC sides of the converters, a controller supplying control signals to the converters for controlling operation of switching transistors thereof, which method comprises:
- calculating rotor current command signals to control the converter switching transistors to maintain a desired rotor current;
- monitoring the voltage of the utility grid for transients from nominal;
- and
- if a grid transient greater than a first predetermined transient occurs, adjusting the rotor current command signals to reduce rotor current and thereby reduce rotor torque and reactive power to permit continued rotation of the rotor without disconnecting the DFIG system from the grid, whereby the DFIG system rides through the transient;
- and
- following the transient, returning the rotor current command signals to operate as before occurrence of the grid transient.
A controller for a doubly fed induction generator (DFIG) system, such DFIG system having a generator with a stator energized by a grid having a voltage with a nominal value, a driven rotor coupled with the stator, a grid side converter electrically connected to the grid, a rotor side converter electrically connected to the rotor, a DC link connecting the converters, said controller comprising means for supplying control signals to the converters for control of the torque and reactive power from the DFIG system, said controller further comprising:
- means for providing rotor current command signals from the controller;
- means for monitoring the voltage of the grid for transients from nominal;
- and
- means for adjusting the rotor current command signals to permit continued operation of the DFIG system without disconnecting the DFIG system from the grid if a transient greater than a first predetermined transient occurs.
A controller for a doubly fed induction generator (DFIG) system, such DFIG system having a generator with stator energized by a grid having a voltage with a nominal value, a driven rotor coupled with the stator, a grid side converter electrically connected to the grid, a rotor side converter electrically connected to the rotor, a DC link connecting the converters, said controller comprising means for supplying control signals to the converters for control of the torque and reactive power from the DFIG system, said controller further comprising:
- means for monitoring the voltage of the grid for transients from nominal;
- and
- means for activating a crowbar to reduce the voltage of the DC link connecting the converters if a grid transient greater than a predetermined transient occurs, without disconnecting the DFIG system from the grid.
A controller for a DFIG system, such DFIG system having a generator with a stator energized by an AC utility grid having a voltage with a nominal value, a variable speed wind driven rotor coupled with the stator, a grid side AC-DC converter electrically connected to the grid at the AC side, a rotor side AC-DC converter electrically connected to the rotor at the AC side, a DC link connecting the DC sides of the converters, said controller comprising means for supplying control signals to the converters for controlling operation of switching transistors thereof, said controller further comprising:
- means for calculating rotor current command signals to control the converter switching transistors to maintain a desired rotor current;
- means for monitoring the voltage of the utility grid for transients from nominal;
- and
- means for adjusting the rotor current command signals to reduce rotor current and thereby reduce rotor torque and reactive power to permit continued rotation of the rotor without disconnecting the DFIG system from the grid if a grid transient greater than a first predetermined transient occurs, whereby the DFIG system rides through the transient;
- and
- means for returning the rotor current command signals to operate as before occurrence of the grid transient following the transient.
A doubly fed induction generator (DFIG) system comprising:
- a generator with a stator energized by a grid having a voltage with a nominal value;
- a driven rotor coupled with the stator;
- a grid side converter electrically connected to the grid;
- a rotor side converter electrically connected to the rotor;
- a DC link connecting the converters;
- and
- a controller supplying control signals to the converters for control of the torque and reactive power from the DFIG system;
- means for providing rotor current command signals from the controller;
- means for monitoring the voltage of the grid for transients from nominal;
- and
- means for adjusting the rotor current command signals to permit continued operation of the DFIG system without disconnecting the DFIG system from the grid if a transient greater than a first predetermined transient occurs.
A doubly fed induction generator (DFIG) system comprising:
- a generator with a stator energized by a grid having a voltage with a nominal value;
- a driven rotor coupled with the stator,
- a grid side converter electrically connected to the grid;
- a rotor side converter electrically connected to the rotor;
- a DC link connecting the converters;
- a controller supplying control signals to the converters for control of the torque and reactive power from the DFIG system;
- means for monitoring the voltage of the grid for transients from nominal;
- a crowbar constructed and arranged to reduce the voltage of the DC link;
- and
- means for activating a crowbar to reduce the voltage of the DC link connecting the converters if a grid transient greater than a predetermined transient occurs.
A DFIG system comprising:
- a generator with a stator energized by an AC utility grid having a voltage with a nominal value;
- a variable speed wind driven rotor coupled with the stator;
- a grid side AC-DC converter electrically connected to the grid at the AC side;
- a rotor side AC-DC converter electrically connected to the rotor at the AC side;
- a DC link connecting the DC sides of the converters;
- a controller supplying control signals to the converters for controlling operation of switching transistors thereof;
- means for calculating rotor current command signals to control the converter switching transistors to maintain a desired rotor current;
- means for monitoring the voltage of the utility grid for transients from nominal;
- and
- means for adjusting the rotor current command signals to reduce rotor current and thereby reduce rotor torque and reactive power to permit continued rotation of the rotor without disconnecting the DFIG system from the grid if a grid transient greater than a first predetermined transient occurs, whereby the DFIG system rides through the transient;
- and
- means for returning the rotor current command signals to operate as before occurrence of the grid transient following the transient.
Dependencies are inferred from the claim text.