Adaptive current damping module for improved power converter control in wind turbine systems

A control system for a wind turbine system, the wind turbine system comprising a generator and a power converter, the power converter comprising a plurality of switching devices and a current damping module, the control system comprising:

• one or more processors and one or more memory devices configured to store instructions that when executed by the one or more processors cause the one or more processors to perform operations, the operations comprising:
• determining a flux magnitude of an air-gap between a rotor and a stator in the generator, wherein determining the flux magnitude of the air-gap comprises estimating the flux magnitude with a flux magnitude estimator;
• determining an orientation adjustment reference signal for the current damping module based at least in part on the determined flux magnitude;
• and
• controlling a duty cycle of the plurality of switching devices so as to control the power converter based at least in part on the orientation adjustment reference signal;
• wherein the power converter is controlled such that the wind turbine system exhibits a positive damping characteristic for a subsynchronous frequency range.

A doubly fed induction generator (DFIG) wind turbine system, the DFIG wind turbine system being coupled to an electric power transmission and distribution grid comprising:

• a DFIG generator, the DFIG generator comprising a rotor and a stator;
• a power converter, the power converter comprising a plurality of switching devices and a current damping module;
• and
• a control system, the control system comprising one or more processors and one or more memory devices configured to store instructions that when executed by the one or more processors cause the one or more processors to perform operations, the operations comprising:
• determining a flux magnitude of an air-gap between the rotor and the stator in the DFIG generator, wherein determining the flux magnitude of the air-gap comprises estimating the flux magnitude with a flux magnitude estimator;
• determining an orientation adjustment reference signal for the current damping module based at least in part on the determined flux magnitude;
• and
• controlling the power converter based at least in part on the orientation adjustment reference signal;
• wherein the power converter is controlled such that the DFIG wind turbine system exhibits a positive damping characteristic for a subsynchronous frequency range comprising a frequency range that is less than a frequency of the electric power transmission and distribution grid.