A Novel Saturated Amorphous Alloy Core Based Fault Current Limiter for Improving the Low Voltage Ride Through Capability of Doubly-Fed Induction Generator Based Wind Turbines

This article proposes the use of a novel saturated amorphous alloy core-based fault current limiter (SAACFCL) to improve the low voltage ride through (LVRT) capability of doubly-fed induction generator (DFIG) based wind energy systems, especially during voltage sag events. Compared to the traditional cores, which are widely used in fault current limiter (FCL), amorphous alloy core possesses a very narrow B-H loop, which indicates that the SAACFCL requires a smaller dc excitation current, and it will incur low core losses. Under normal conditions, this developed SAACFCL accomplishes low impedance and has a negligible impact on the network operation. During grid faults, a deep voltage sag causes large fault currents that desaturate the SAACFCL core, increasing its impedance, which limits the fault currents and improves the LVRT capability of DFIG systems. The SAACFCL is designed and characterized by ANSYS software. To validate the performance of the SAACFCL, a DFIG-based system equipped with the SAACFCL has been modeled in MATLAB/Simulink. The simulation results with and without the SAACFCL show that the SAACFCL is capable to achieve the LVRT successfully and can meet the grid code requirement. The performance of the SAACFCL has also been compared with that of the saturated iron core FCL (SICFCL) and superconducting FCL (SFCL). The SAACFCL promises better performances than SICFCL and SFCL. A small scale SAACFCL has been designed, developed, and tested in the laboratory to check its performance. The experimental results show that the proposed SAACFCL can effectively reduce the level of fault current and mitigate voltage sag experienced by the DFIG.