Abstract

This paper presents an assortment study between the virtual inertia control (VIC)-based a new optimal PID controller, load frequency control (LFC), and the digital protection for an islanded microgrid (MG) taking into consideration the emerging level of renewable energy resources (RERs), which is a promising solution. However, the reduction in system inertia due to increasing the amount of RERs causes undesirable impact to MG dynamic stability, threatens the system security, and could lead to complete blackouts as well as damages to the system equipment. Therefore, maintaining the dynamic security in MGs is one of the important challenges, which considered in this paper using a specific design of a digital over/under frequency relay (OUFR) with coordination of the VIC to protect the MG against high-frequency variations. To prove the effectiveness of the proposed coordination strategy, it has been tested considering sudden load change, high integration of RERs. Moreover, the sensitivity analysis of the presented technique was examined by varying the inertia level of MG system. The results stated that the proposed coordination can effectively regulate the MG frequency and maintain the dynamic stability and security.