In this paper a new structure for fault current limiter is proposed. In proposed structure the superconductor coil is replaced by a copper coil and the losses of copper coil and power electronic devices are compensated by an auxiliary circuit. The results show that the proposed structure has less undesired effect on normal operation of system compared with ordinary superconductor type.  The main advantageous of proposed structure are no need to superconductor technology and its control-less operation. The analytical analysis and designing characteristics for DC reactor are presented. Also, the simulation and experimental results are presented to show the effectiveness of proposed structure in fault current limitation.

This study presents a modified transient current limiter (MTCL) for mitigation the inrush current of transformers. The MTCL is based on conventional transient current limiter (TCL), which, its configuration is modified to overcome the TCL drawbacks of operation. The proposed MTCL offers lower power losses and voltage/current THD during normal operation mode. It needs only one limiting reactor instead of two limiting reactors, which results in cost saving. The theoretical analysis of the MTCL for suppressing the inrush current has been presented and the performance was tested by PSCAD/EMTDC simulation anda experimental prototype. Both simulation and experimental results showed that the MTCL is effective for suppressing the transformer inrush current. Also, the capability of the MTCL for suppressing the transformer inrush current was compared with the conventional TCL.

In this paper, design and application requirements for a fault current limiter (FCL) which can be made by a LC parallel resonant circuit are described. The electrical performance of this kind of fault current limiter and sensitivity analysis of its components is simulated by EMTP software. The obtained results for application of this kind of FCL in a distribution system show several interesting characteristics which can be regarded as an effective means for utility power quality improvement purposes.

Excessive transient inrush current of the power transformers has some negative impacts such as: transformer lifetime reduction، mal-operation of the relevant protections، and power quality degradation. In some cases، the energization impact on power quality may lead to catastrophic damages to the system such as offshore stations. Therefore، suppression of inrush current is vital in such applications. In this paper، a new Solid-State Inrush Current Limiter (SSICL) is proposed for medium voltage power transformers with the capability of integration with already existing circuit-breakers. The proposed SSICL consists of three similar sets of bidirectional semiconductor switch and an inrush current limiter resistor. Using a Kalman Filter based strategy، transformer inrush current is suppressed during magnetization process. In fact، built up profile of the inrush current is dictated in accordance with the estimated current by a slow dynamic Kalman filter. The proposed SSICL is simulated in MATLAB-SIMULINK and a single-phase experimental prototype of the limiter is implemented. The proposed control scheme was implemented using dsPIC30F4011. In order to evaluate the performance of the SSICL، some experiments were carried out. Simulation and Experimental results show that the proposed SSICL can considerably suppress inrush current of the transformer.

The presence of distributed generations (DGs) in the power systems is causing problems such as increasing the short circuit current levels which may exceed the rating of existing circuit breakers and can damage system equipment. The utilization of fault current limiters (FCLs) in the network can be an effective method to overcome the above problems. Furthermore، FCL has the benefits such as improving the system security and reliability. FCL benefits depend on the number، installation location، and impedance of FCL. For this end، we require a method to determine the optimum number، impedance and locations for FCL placement. In the considered method، we have modeled the FCL placement as an optimization problem while the objectives are; bus fault current difference، reliability، the number and impedance of FCLs. Moreover، to solve the proposed problem، a new multi-objective optimization algorithm based on particle swarm optimization has been implemented. In the algorithm، several iterations have been considered، and the non-dominated solutions are extracted and stored in an external repository in the iterations. Finally، a fuzzy clustering technique is used to control the size of the repository during the algorithm evolution. The proposed approach is tested on a test system، namely، RBTS 2. The obtained results demonstrate the effectiveness and feasibility of the new method.

Fault current limiters (FCLs) are proposed widely in literature for improving different characteristics of electric power system. Solving protection problems in smart distribution networks in presence of distributed generation (DG) is an example for the applications of FCLs discussed in recent papers. Voltage sag during faults is a power quality (PQ) concern in the power system. In this paper, it is shown that in smart distribution networks including microgrids, FCL can effectively alleviate this problem, according to the fault location. Therefore, a bidirectional non-superconducting fault current limiter (BNSFCL) is presented in this research, so that the bidirectional fault suppression has become available. Analytical analysis and simulations are provided to validate the effectiveness of the BNSFCL topology. Results show that by using proposed structure in distribution networks with microgrids, both protection and PQ status are enhanced, i. e. the BNSFCL prevents deep voltage sag and protection mis-coordination. The proposed topology can be applied in smart grid architecture _where the bidirectional current flow has made conventional protection schemes useless_ effectively and can have acceptance for implementation as one of the future power system components.

This paper deals with presenting a method for improving diode-based frequency selective limiter’s performance. High limiting level, low spike leakage, low recovery time, and simple design procedure made the diode-based frequency selective limiter a good option for protection of smart antenna system from high power microwave threat. Unfortunately, due to the method of nonlinear resonator realization in these limiters, in the presence of high power out of limiting band signals of each channel limiting band attenuation in passing state of these limiters increases. In this paper, band-pass filter is employed to decreasing the effect of high power out of limiting band signals on the attenuation in the passing state of limiter. By using this technique a 2-channel FSL in center frequencies of 4.2GHz and 4.6GHz, with 0dBm limiting threshold, 30dB limiting level, and 200MHz limiting bandwidth is designed. Simulation results show that using this technique can decrease the effect of out of limiting band signals on attenuation of passing state by 9dB, and increase the linearity of frequency selective limiter in the passing state of limiter.

HV substations equipment protection as a strategic point on the power network always has attracted attention of power planners. An increase in the generation capacity and interconnected operation of neighboring grids can result in an increase in the fault currents during a contingency in a power system. The increased fault currents may exceed the maximum fault current rating of existing protective apparatus. Therefore FCLs are used which perform switching operations quickly and safely in the event of a power system fault. This study proposes a methodology for determining the location of FCL by considering the reduction of fault current and the reliability indices according to the location of FCL in a conventional arrangement such as one breaker and half. Finally, the fuzzy decision method which is suitable for solving problems with no advantages respect to each other to determine the optimal location of FCLs is used.