<p>The present power system integrated with renewable energy sources is subject to several risky events, such as unplanned weather changes, intermittent energy sources, and natural hazards. The outage of the generating sources, along with intermittent renewable generation, also affects the reliability of the power system. Power system security is an aspect of the power system that considers both the risk and reliability of the power system together. The present work provides an overview of the power system security in terms of risk and reliability. Integrating renewable energy sources in the present power system is challenging and involves several uncertain factors, which have also been highlighted. The manuscript highlights the risks and uncertainties associated with the power system. The present work has also studied various risk and reliability evaluation methodologies.</p>