The current trend in power system evolution involves the extensive integration of Renewable Energy Sources (RESs) to address the environmental concerns associated with traditional power plants. Consequently, the capacity of RESs and Distributed Generators (DGs) is rapidly expanding worldwide, with even higher levels of penetration planned for the next two decades. While this increased incorporation of RESs and DGs is beneficial for renewable energy utilization, it poses challenges to power system stability, especially regarding frequency stability. The lack of inertia in power electronics interfaces (such as converters/inverters) means that the rising penetration of RESs and DGs will further diminish system inertia and impact the system's damping characteristics. Therefore, the growing presence of RESs not only negatively affects power system stability but also creates new challenges in maintaining power system frequency stability. The Sultanate of Oman's government is focused on harnessing renewable energy for electricity generation to lower carbon emissions and decrease reliance on fossil fuels. The goal is to achieve 20% of electricity production from renewable energy sources by 2030 [1]. The employment of inverter-based renewable energy generators impacts the inertia and the rate of change of frequency (ROCOF) in the main interconnected system (MIS). To support the Sultanate's vision of increasing reliance on renewable energy sources as per the plans in this regard, this Thesis focuses on studying the application of the virtual inertia concept to the MIS to maintain system frequency stability and facilitate the future implementation of renewable energy projects while ensuring network stability. The impact of the increased penetration of renewable energy sources on the inertia level of the MIS was studied using the DIgSILENT software. Additionally, a virtual inertia control system based on advanced algorithms (Type 2 fuzzy-PID controller) was developed and tested on MIS model using MATLAB/Simulink software. The efficiency of the developed controller was verified through several tests that included scenarios with high penetration of renewable energy sources.