Overcurrent Protection of a Stand-alone Microgrid with Static and Rotational Generators: Case Study of Tsumkwe Microgrid

Tsumkwe standalone microgrid in Namibia is protected using fuse-based protection system that lacks proper coordination. This paper proposes a coordinated overcurrent protection scheme to overcome the protection challenges of the current protection method. The effectiveness of the proposed protection scheme is analysed and compared to the current protection system under fault occurrences in the microgrid simulated using DIgSILENT Powerfactory. The parameters used to compare these methods of protection are the fault clearing time for the primary and secondary protection devices as well as the coordination time intervals for the respective protection methods by weighing it against the acceptable margin stipulated in the IEEE standard 242. The results obtained from these simulations have shown that the proposed overcurrent protection schemes serve more advantages in terms of speed of operation and coordination between the protection devices as compared to the current protection system.