Modeling and Analysis of DC Pole-to-Pole Fault in High-Frequency-Bus Based Power Electronic Transformer

Multi-port power electronic transformer (PET) is a key component for future power grid. A kind of PET topology based on high-frequency-bus (HFB) has attracted attention because of its lower cost and higher efficiency. But conventional HFB-PET has not been able to deal with DC short-circuit fault yet. With the presence of the unique HFB structure, traditional DC short-circuit model will result in error. So, a modified DC short-circuit model is needed for fault analysis and protection. The paper proposes a modified short-circuit model for HFB-PET, which explains the mechanism of fault transient process and provides a way to calculate the fault current mathematically. The numerical solution of the model is proved to be faster than circuit simulation one and the result is more accurate than conventional analytical method. The validity and accuracy of the model is verified by comparison with simulation in DSIM 2021a and hardware-in-loop real-time simulation.