Novel Grounding and Protection Strategy for DC Microgrid Restraining Fault Current

The dc microgrid affirms its prominent presence by optimally exploring distributed generations' benefits and reducing greenhouse emissions. The absence of effective protection and grounding solutions limits the broad adoption of dc microgrids. The proposed work presents a grounding system design that meets the grounding and relaying requirements, like reducing common mode voltage, minimizing the fault current magnitude, and facilitating high-impedance fault detection by injecting high-frequency oscillations at fault inception. It presents a minimal fault current footprint at the converter side, reducing the stress on converters. The current scheme's adjoint index-based rate of change of current is used to detect and classify various types of faults. The proposed relaying scheme offers high-speed fault identification, averting possible catastrophic damage to the system. Moreover, the proposed relaying strategy involves only a single parameter with no external circuit element required for fault identification, making this invention economically viable. The scheme's performance is analyzed using PSCAD/EMTDC software data under various operating conditions, including instantaneous load and source switching operations. High efficacy, reliability, sensitivity, fast operation, and restraining fault intensity are strategic features of the scheme. The comparative performance with other schemes at various performance indices is also discussed.