Detection of DC System Faults Based on the Principle of Threshold Violation in i-r Plane

Abstract

Widespread adoption and practical implementation of dc microgrids in intelligent and evolved power grids demand standardized protection philosophy, which can govern their dedicated protection schemes. In dc microgrids, fault identification and isolation without de-energizing the system is a major concern, which is addressed in this article. This article proposes a dedicated protection solution for low-voltage dc (LVdc) networks, which works on the principle of threshold violations by utilizing local $r_{ij}$ measurements. The estimated thresholds of $r_{ij}$ , $\hat{r}_{ij}$ for each of the installed intelligent electronic devices are also mathematically derived. The developed scheme avoids two terminal information utilized in the principle of directionality violations. The overall scheme is validated on a LVdc test-bed for different fault locations and high fault resistance. The scheme is also validated in the presence of white Gaussian noise in input measurements to the algorithm and is observed to be highly responsive with fault detection accomplished within a few microseconds.