Analysis of Short Circuit Impact on Solid State Transformers

The Solid State Transformer as a main component in DC grids plays a major role in detecting and protection against grid faults. Therefore, this paper aims to identify and analyze some main characteristics and vulnerabilities of the fault behavior of a Solid State Transformer. A short circuit in a DC grid, fed by a dual active bridge (DAB), is simulated and analyzed. The fault current is split into three parts and examined individually. The impact of the current in the converter, especially on the freewheeling diodes is evaluated. Parameter variations in grid impedance and output filter show the impact on the converter short circuit capability.