Behavior Modeling of Lightning Overvoltage and MOA-based Protection for Floating Ground SST

Abstract

Solid-state transformer (SST) based super charge station (SPS) have become an attractive substitute for state-of-the-art charge stations because of their high efficiency, high power density, and convenient maintenance and power expansion However, compared to traditional SPS system which is connected to MV grid with a bulky line frequency transformer, SST is more fragile to failure because that it directly connects to the MV grid. Different kinds of surge events would be seen in the MV grid, among which lightning is one of the most serious scenarios. Therefore, the lightning influence on the Metal Oxide Arrester (MOA) clamped floating SST is modeled and analyzed. The modeling process of such an SST system, including the lightning wave and MOA, is shown. Evaluation results show that voltage stress between phases would hugely increase during the lighting, and this effect can be eliminated by MOA connected between phases.