## 1 Introduction  
A stand-alone DC microgrid is an independent, controllable, small-scale electrical system in the presence of Distributed Generators (DGs), controllable and non-controllable loads, power electronic components, and protective devices [1]. With the rapid development and integration of renewable energy resources, a novel alternative is required to ensure stable operation under different operation conditions. Based on the literatures, high- and low-voltage DC systems are recognized as an efficient method for power transmission and distribution. Since [PERSON]'s time, the DC system has been implemented for energy supply purposes, but due to the lack of standards and technologies, AC system have been leading the DC network. Whereas the emerging of new power electronics and distributed energy resource technologies have made it easier to interconnect power components and build a multi-terminal DC system. However, DC short-circuit protection is still considered to be one of the major challenges for DC network applications in terms of small- and large-scale power transmission and distribution [2]. A large and growing body of literature has relied on low-voltage DC breakers in terms of a DC network or microgrid protection. More recently, in [3], a protection scheme for the hybrid AC/DC low-voltage distribution system based on transient stability analysis, backed by radial distribution system simulation and verification, has been proposed. In [4], a mechanical DC breaker for real-time application is discussed. This study aims to propose a simulation mechanism for a DC breaker mechanical design at the simulation phase. This study formulates the components of a DC breaker (such as a high-speed vacuum interrupter, injection circuit, surge arrester, and residual switch) to evaluate the interruption of the DC fault in real-time. In [5], an optimized method was hired to calibrate the DC circuit breaker with the help of an active injection circuit. This study took an optimized approach to enhance the DC circuit breaker's performance according to its local fault current in a critical situation. The PSCAD(r) platform was used to evaluate the effectiveness of the proposed algorithm which could guarantee that the di/dt was within a safe limit during an interruption. In [6], a framework was exposed based on a mathematical morphology approach to detect and protect a DC distribution network. This study characterized fault at a low-voltage distribution network, which focused on the DC short-circuit fault with low impedance, and a high impedance fault with arc concepts. The proposed filter-based approach is known as a cost-effective solution, in which there is no need for a communication link between relays or between a relay and its components. In [7], a protection and control scheme for DC multi-microgrid configuration was proposed. This study tried to come up with an integrated solution in terms of simultaneous protection and control. The effectiveness of the study was evaluated through an experimental microcontroller circuit. In a small-scale DC system, the distributed renewable generators, storage system, and loads can interface with the common bus through DC-converters, and prevent multiple energy conversion steps to deliver the most efficient and sustainable energy supply for power demands. Compared to AC, the DC power system does not have synchronization, reactive power, harmonics, skin effect, high heat-loss, and low-efficiency problems [8; 9]. Also, there is no need for inverters to integrate DC power generators, storage devices, and DC loads with the direct current system. They can be integrated by highly efficient DC-DC converters to prevent large amounts of energy loss and system complexity. In addition, in any small-scale isolated microgrid, the total power generation capacity should be more than the maximum existing load to completely supply the load in any condition.