Novel Fault tolerance in Three Stage Solid State Transformer

Abstract

Solid State Transformer (SST) have gained a considerable attention of designer and engineers. They offer many advantages over conventional transformer like voltage regulation, compact design, flexibility, high efficiency and power quality. In addition, the SST provides an intermediate DC bus connection between renewable energy sources and storage battery. This enables SST to de deployed in distribution and renewable energy system. In such systems a continuous operation is desired. The power electronics semiconducting switching devices raises a concern about the reliability of SST. A slight over current to the rated capacity of semiconducting devices can damage the SST permanently where a normal transformer's copper winding has capacity to withstand the short circuit current. In this paper, a fault tolerant three stage SST with redundancy is discussed. For fault identification voltage sensing method is deployed for the stages of dual active bridge converter (DC-DC converter) and inverter (DC-AC converter) stages and current sensing method for PWM rectifier (AC-DC converter) stage. Current measurements are done for semiconducting module and voltage measurements are done across the output of each stage. Thresholding is applied to every measured parameter for fault identification. MATLAB simulation is carried out and results are presented. The proposed system for fault detection and redundancy corrective action is capable of taking corrective action within single cycle.

URN:NBN:sciencein.jist.2024.v12.806