Protection Scheme for Low Voltage DC Microgrid Based on Voltage Rise Across Terminal Inductor

This paper presents a novel protection scheme based on voltage rise measured across terminal inductor. The terminal inductor at both ends of the cable is introduced for fault detection which further help in increasing the rise time of the fault current and provide a sufficient time for fault detection. Further, the voltage rise across the terminal inductor is measured for fast fault detection. This rise in inductor voltage is measured with the help of time parameter which is added to increase the robustness of the proposed scheme in case of severe close-in fault conditions. Thus, Δt is calculated as time required for the inductor voltage to increase from
$V_{min}$
to
$V_{\max}$
. Comparing the Δt with predefined threshold value gives the discriminating criteria for internal and external fault detection. The proposed scheme is validated on 380V bipolar DC microgrid test system designed in PSCAD/EMTDC environment. The obtained results shows the selectivity and efficacy of the proposed scheme. The proposed scheme can detect the internal fault within 1ms which shows the fast response of the given scheme.