New Fault Detection Method for Low Voltage DC Microgrid with Renewable Energy Sources

With the development of renewable energy sources (RES), the use of microgrids is becoming more prevalent. The low voltage direct current (LVDC) microgrid provides numerous advantages, including increased convenience, improved efficiency, loss reduction, and simple integration with PV and BESS. There are currently no perfect fault detection methods for LVDC microgrids. Solutions, such as protection relays and coordinates, must be found as soon as possible to reduce costs and provide better quality DC power. This paper proposes a new fault detection method for LVDC microgrid with RES for the development of an effective method. A 1500 Vdc (+ 750 Vdc) LVDC distribution system in South Korea composed of PV, BESS, and load, which are major elements in the LVDC microgrid, was modeled using PSCAD s/w. Further, we developed a fault detection algorithm using various fault analyses. The proposed new fault detection method consists of instantaneous current change rate, the detail coefficient of the discrete wavelet transform, and absolute detail energy. As a result of the simulation and performance verification, the proposed fault detection method demonstrates reliable operation in several cases.