The Behavior of DC Microgrid Connected Solid State Transformer During Internal Short Circuits

Solid State Transformer (SST) enabled DC micro-grids are a modern solution for replacing the conventional Low-Frequency Transformer (LFT) by enhancing the system power density. Further, using SSTs in power systems has several additional advantages which are impossible with LFTs. As the SST is made out of sensitive power electronic components, safety must be guaranteed successfully to maintain a reliable operation. Also, the existing system will operate differently fundamentally with the integration of SST and the Low Voltage (LV) DC network will experience new LV fault profiles. SST-enabled power systems can be vulnerable to several kinds of faults such as overcurrent, overvoltage, and switching failures which will be discussed in this research. Therefore, it is more important to conduct a fault analysis based on different types of faults in the SST-enabled DC microgrid. The manuscript is mainly focused on three areas faults in the Medium Voltage (MV) side of the SST, faults within the SST, and faults in the Low Voltage (LV) side of the SST. The main objective of this research is to study the behavior of the SST in faulty conditions mentioned above. Different types of faults in a DC microgrid based on SST are simulated and the results are discussed and analyzed in this paper. Further, it has been found that the SST has a moderated capability for fault-tolerant operation during the faults.