A Current Sensorless Portable Power Electronic Fault Localization Unit for LVdc Microgrids

Precise identification of fault location in dc microgrids is essential for prompt maintenance and quick power restoration. This article proposes a portable power electronic fault localization unit (PEFLU) which can identify the fault location within a low-voltage dc (LVDC) microgrid by estimating the inductance of the distribution line. The proposed scheme is based upon a current sensorless approach, and hence, compared to existing methods, it eliminates the need for current sensors and high-frequency sampling stages for fault localization. The proposed unit operates post de-energization of faulty line using internal measurements (i.e., terminal voltage measurements of PEFLU) to locate the fault, without involving any measurements from other points of the distribution line. The sensors for PEFLU act upon low bandwidth average voltage measurements rather than instantaneous voltages in order to estimate fault location. This paper discusses the theory behind estimation of fault location, which is verified using simulation analysis on a low voltage dc microgrid system. The proposed concept has also been validated using a laboratory scale testbed using converter prototype of PEFLU acting on a distribution system.