Transient Performance Augmentation of DFIG Based Wind Farms by Nonlinear Control of Flux-Coupling-Type Superconducting Fault Current Limiter

Any fault related to grid is a matter of great concern for doubly fed induction generator (DFIG) based power system as DFIG's stator windings are connected to the grid directly. To augment the transient performance of the DFIGs, superconducting fault current limiter (SFCL) is a certified device. To boost the performance of a flux-coupling-type SFCL (FC-SFCL) by ensuing the adaptive use of fault current limiting impedance based on fault severity, rather involving the full impedance unnecessarily, a nonlinear controller (NC) for FC-SFCL (NC-FC-SFCL) is presented in this paper. Reason behind choosing a straightforward NC for this work is to have simple implementation capability with the full flavor of a nonlinear controller. Effectiveness of the NC-FC-SFCL is compared with conventionally controlled FC-SFCL for various fault scenarios. Simulation results suggest that, NC-FC-SFCL can improve the overall fault ride through (FRT) capability which is verified both graphically and numerically. Additionally, this effective use of the fault current limiting impedance guarantees better transient sub-synchronous resonance (SSR) performance, and exhibits better total harmonic distortion responses.