Design Consideration of a Dual-Functional Bridge-Type Fault Current Limiter

To sufficiently utilize a bridge-type fault current limiter (BTFCL) in the distribution grids, this article proposes a dual-functional BTFCL (DF-BTFCL), which can work either at the BTFCL mode to limit faulty currents or at the dynamic voltage restorer (DVR) mode to compensate grid-voltage fluctuations. The proposed DF-BTFCL can flexibly switch between the two modes by either activating a dc capacitive circuit or a dc inductive circuit. The inductive circuit can adjust the equivalent series impedance to limit the faulty current in an acceptable range, and the dc capacitance circuit can provide dc support to enable the DVR operation. The proposed DF-BTFCL can immediately limit the increasing rate of the faulty current without any fault detection delay, and it is similar to the conventional BTFCL. Transient processes between the switch of the two operation modes are analyzed, and the key parameters of the DF-BTFCL system are designed in detail. Simulations and experimental results both clearly prove the feasibility and effectiveness of the proposed DF-BTFCL.