Solid-state Transformer Inrush Current Limiter for Power Quality Improvement

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.