A new high-performance bridge-type fault current limiter (BFCL) is proposed in this study. The proposed BFCL can moderate transient overcurrent in abrupt load change condition and dramatically limit the fault current in fault condition. The key feature of this new BFCL is based on using a switched transformer-type DC reactor. In fact, the secondary side of the transformer is short-circuited during normal condition. Therefore, the transformer has negligible effect on the circuit in this condition. When the load current exceeds a predefined threshold (permissible maximum load current), secondary side of the transformer is opened by an insulated gate bipolar transistor. Consequently, inrush current of the load suppresses in abrupt load change condition or the current increases at a constant rate in fault condition. When current exceeds a higher predefined threshold (in the order of fault current), it is limited via the switched DC reactor and a discharging resistor. Analytical analysis of the proposed BFCL is presented in detail. Simulation and experimental results validate the effectiveness of this structure in abrupt load change and fault conditions.

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Abstract─In this paper, a capacitor switching transient limiter based on a three phase variable resistance is proposed. The proposed structure eliminates the capacitor switching transient current and over-voltage by introducing a variable resistance to the current path with its special switching pattern. This topology has high damping capability due to its resistance nature and low voltage drop and low power losses due to complete bypass of its resistor. Therefore, it does not need auxiliary circuit to compensate voltage drop in normal condition. Also, because of smooth bypass of resistance, it does not make transients on capacitor after bypassing. Analytic Analyses for this structure in transient cases are presented in details and simulations are performed by MATLAB software to prove its effectiveness.

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