The inertia provided by the synchronous generators limits the rate of change of frequency (RoCoF) and maintains system frequency within the limits of stable operation. To meet worldwide green energy obligations, the power system is swiftly integrating renewable energy sources. This transition from synchronous generation to inverter-based resources reduces system inertia, which in turn affects the stability of power system frequency. As a result, maintaining frequency stability has become a significant challenge in modern power systems. Moreover, accurate inertia estimation assists operators in understanding the system’s ability to tolerate severe disturbances such as generation loss, line outage, etc. This chapter explores the developments in the RoCoF based inertia estimation techniques. Furthermore, this chapter examines the performance of the RoCoF based distributed generation disconnection scheme. It also evaluates the RoCoF based load-shedding schemes in power systems integrated with inverter-based resources. The performance of the various suggested methods is validated through simulations conducted on a specific test system, namely the IEEE 39 bus system. A quantitative analysis of different RoCoF based inertia estimation methods is conducted and presented in the chapter. Further, the impact of inverter-based resources on RoCoF based load shedding schemes and generation disconnection schemes are also analyzed on the IEEE-39 bus system. This study also analyzes the correlation between the inertia distribution index and the RoCoF. These insights have significance for modern power systems, establishing a basis for future research and practical implementation.