The EPS reacts to external factors by changing the parameters of the mode – modules and voltage phases, power flows and currents of its element, speeds of rotations of synchronous and asynchronous machines. The composition and magnitude of these changes depend on both the set and the strength of the external disturbances and the properties of the EPS itself - circuit topology and its parameters (resistances, conductivities, a combination of capacitive, inductive and active resistances), control actions, characteristics of regulators, dynamic characteristics of the elements and other automation. First of all, it is very important to know the sensitivity of the parameters of its mode towards external disturbances, to be able to determine the significance of those or other reactions from the point of view of the mentioned management criteria in order to ensure stability. Second, it is important to highlight the parameter groups, whose reactions are similar, coordinated, coherent to disturbances, and third, to be aware of the factors, which affect the sensitivity of the EPS in order to determine the desired change of these factors both during operation and designing (development) of the EPS. Experience of the EPS calculations shows, that the EPS is dissimilar and not full-strength like any complex system. In particular, it is shown by the fact that the mode parameters of some elements of the EPS (nodes, communications) are relatively more responsive to disturbances on average. Moreover, the disturbances put to different places of the EPS cause significant reaction of the same mode parameters: voltage modules are mostly changed at the different localization of disturbances of the same nodes; one and the same elements are overloaded by current. This article consists of the following parts: • A Brief Description Of Used approaches - The chapter describes the current methods and approaches to the analysis of EPS; • Theoretical background - The chapter describes the theoretical basis, the proposed method; • Case Study on the Latvian energy system - The chapter analyzes the EPS using the approach described in the theoretical part; • Summary - Chapter devoted to conclusions about the proposed method.