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The fault ride-through (FRT) capability and fault current issues are the main challenges in doubly fed induction generator- (DFIG-) based wind turbines (WTs). Application of the bridge-type fault current limiter (BFCL) was recognized as a promising solution to cope with these challenges. This paper proposes a nonlinear sliding mode controller (SMC) for the BFCL to enhance the FRT performance of the DFIG-based WT. This controller has robust performance in unpredicted voltage sag level and nonlinear features. Theoretical discussions, power circuit, and nonlinear control consideration of the SMC-based BFCL are conducted, and then, its performance is verified through time-domain simulations in the PSCAD/EMTDC environment. To reduce the chattering phenomenon and decrease the reaching time, it used the exponential reaching law (ERL) for designed SMC. Also, the SMC-based BFCL performance is compared with the conventional and PI controller-based BFCL for both symmetrical and asymmetrical short-circuit faults. Simulation results reveal that the SMC-based BFCL provides better performance compared with the conventional and PI controller-based BFCL to enhance the FRT.

There are various types of fault current limiters (FCLs), which are made of different superconducting materials and have different designs. The bridge-type FCL is mainly composed of a diode bridge rectifier and a DC reactor. This FCL can control the fault current by controlling the DC reactor current. To enhance this capability, a resistor parallel with a semiconductor switch has been used in series with DC reactor. In this article, hysteresis technique has been proposed and integrated in this structure, which not only limit the fault current but also reduce total harmonic distortion (THD) at the point of common coupling (PCC). Therefore, the performance of all loads connected to PCC will not be affected during fault. The theory and properties of the proposed bridge-type FCL for limiting the fault current and producing sinusoidal voltage at PCC during fault has been presented, and its model has been simulated by power systems CAD/electromagnetic transients including DC. It is shown that the proposed FCL can effectively reduce the THD at PCC and limit the fault current.

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