Solid-State Inrush Current Limiter Controller Based on Inrush Prediction for Large Transformers

Inrush current problems of the industrial transformers are occasionally more serious than the utility transformers. A new Solid-State Inrush Current Limiter (SSICL) is proposed for medium voltage power transformers. The SSICL consists of three similar sets. Each set includes a bidirectional semiconductor switch and an inrush current limiter resistor. Using a control strategy based on Kalman filtering, 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. A single-phase prototype SSICL is developed and tested. The proposed control scheme is simulated in MATLAB-SIMULINK. By using Real Time (RT) toolbox of the MATLAB software and a PCI_1711U, interrelationship between the SSICL and its controlling system is realized. Some experiments are carried out to evaluate the performance of the SSICL. The results show that the proposed SSICL can considerably suppress inrush current of the transformer