Time and frequency domain methods to evaluate grounding strategies for medium voltage DC shipboard power systems

Abstract

Several key performance parameters of shipboard power systems are affected by the grounding scheme applied. The grounding scheme impacts the nature of voltage transients during switching events and faults, identifiability and locatability of ground faults, fault current levels, and power quality. Power system simulations play an important role in choosing an appropriate grounding scheme and optimizing its components. The tools typically used for power system analysis need to be carefully tested to determine if they are appropriate for modeling effects of different grounding schemes and in particular the high frequency transients. This paper sheds light on modeling and validation techniques specific to grounding models. Furthermore, insight is provided to present research into new types of power system modeling techniques based on scattering parameters for improved accuracy at higher frequencies of interest. A testbed designed to study the impact of different types of grounding schemes is also introduced and first characterization measurements in the frequency domain provided. The paper concludes with an outlook to future work, which will focus on rigorous validation of the models developed.

A Hardware-in-the-Loop Platform for DC Protection

“…The voltage recovery is governed by the RC time constant of R og and C og . To get the exact value of the parasitics to ground, one would have to use a Network Vector Analyser (NVA) to extract S-parameters or make an FEA model, for example, with COMSOL Multiphysics [60]. However, this changes with the geometry of the system.…”