Short-Circuit Fault Detection and Isolation Using Filter Capacitor Current Signature in Low-Voltage DC Microgrid Applications

This article describes a novel short-circuit (SC) fault detection approach to protect the low-voltage dc microgrid (LV-DCMG). The SC faults are the most common fault in the dc power system and can cause severe hazards if not isolated. Since a DCMG is a capacitor-dominated grid, the proposed scheme utilizes these filter capacitor current dynamics. An LV-DCMG system is considered for building the application to realize the proposed fault detection scheme. Active sources such as solar photovoltaic and battery are connected to the passive loads through a dc-dc converter, dc cable, and solid-state relays. The proposed method considers an average of the capacitor current as a detection parameter. An iteration-based isolation configuration is also suggested for a zonal type of distributed network. Furthermore, a selection procedure of the thresholds is also presented in detail. The validity of the proposed approach is verified through both digital simulation studies and DSP-based experimental studies. The proposed approach is capable of detecting both low and high impedance faults.