Fault-tolerant wind energy conversion system

A method, comprising:

• monitoring for a fault in an electrical grid coupled to a doubly fed induction generator (DFIG) comprising a rotor and a stator;
• and
• after monitoring a fault in the electrical grid:
• controlling rotor-side converter (RSC) circuitry coupled to at least the rotor to maintain reactive power in the DFIG;
• and
• controlling nine-switch converter circuitry coupled to the stator and the electrical grid to maintain a pre-fault voltage across windings in the stator;
• wherein controlling the RSC circuitry further comprises allocating responsibility to the RSC circuitry for supplying a first portion of an active current requirement and responsibility to grid-side converter (GSC) circuitry in the nine-switch converter circuitry for supplying a second portion of the active current requirement, the nine-switch converter circuitry comprising a first independent three-phase output corresponding to the GSC circuitry coupled to the grid through an interfacing inductor to control normal operation in the DFIG and a second independent three-phase output corresponding to neutral-side converter (NSC) circuitry coupled to a neutral side of windings in the stator to provide series voltage compensation to the DFIG when a fault occurs in the grid;
• and
• wherein controlling the nine-switch converter circuitry further comprises causing the NSC circuitry to generate compensating voltages on the neutral side of the of the stator winding.

At least one non-transitory machine-readable storage medium having stored thereon, individually or in combination, instructions that when executed by one or more processors result in the following operations comprising:

• monitoring for a fault in an electrical grid coupled to a doubly fed induction generator (DFIG) comprising a rotor and a stator;
• and
• after monitoring a fault in the electrical grid:
• controlling rotor-side converter (RSC) circuitry coupled to at least the rotor to maintain reactive power in the DFIG;
• and
• controlling nine-switch converter circuitry coupled to the stator and the electrical grid to maintain a pre-fault voltage across windings in the stator;
• wherein controlling the RSC circuitry further comprises allocating responsibility to the RSC circuitry for supplying a first portion of an active current requirement and responsibility to grid-side converter (GSC) circuitry in the nine-switch converter circuitry for supplying a second portion of the active current requirement, wherein the nine-switch converter circuitry comprises a first independent three-phase output corresponding to the GSC circuitry coupled to the grid through an interfacing inductor to control normal operation in the DFIG and a second independent three-phase output corresponding to neutral-side converter (NSC) circuitry coupled to a neutral side of windings in the stator to provide series voltage compensation to the DFIG when a fault occurs in the grid;
• and
• wherein controlling the nine-switch converter circuitry further comprises causing the NSC circuitry to generate compensating voltages on the neutral side of the of the stator winding.