The progressive development in power systems and their operational complexity has aroused interest in the power system dynamic security. Network operators cannot determine the exact state of the system in high-risk situations causing the spread of failures in the system and breakdowns in the worst cases. According to this, the current paper presents the development of a user interface made for the dynamic security assessment of power systems using the theory of situational awareness (SA) to improve the visualization and analysis of the network operator’s information in control centers. Likewise, this paper proposes a methodology, based on measurable information in a WAMS environment, to identify and classify the disturbance or phenomenon affecting the safety of the power system by using online identification of coherent groups, SA indexes and fuzzy logic. Significantly, the purpose of this document does not include control actions when a contingency occurs. It is noteworthy that the validation of this methodology is performed by simulations in the power system New England Test System (39 nodes) by using PSAT toolbox of Matlab®.