During operation, any electric power system (EPS) is subject to minor and major impacts, such as load changes, commutation of the scheme’s elements, changes in active and reactive power generation, automatics (these are examples of normal, relatively small perturbations) as well as short circuits, wide-range regulation of load and sharp load increase, non-sanctioned equipment shutdown and the working of protection and emergency power management systems (examples of major perturbations). The thesis is dedicated to estimating the stability of power systems by means of identifying the most sensitive elements (nodes and lines) of the EPS. This task is relevant because, given the wide variety of schemes and operation modes, the need for using the information about the most loaded weak links becomes substantially bigger with every year. Thus, any EPS has weak links whose conductivity limit can be reached earlier than elsewhere due to scheme and mode changes in the system. Based on this information, for instance, it is possible to identify generators that should be loaded first as power flows in the section increase, forecast the EPS’s reaction to removal of certain parts of the EPS from operation for repairs, identify the EPS’s vulnerable parts as well as to identify the most suitable places for the system’s development and reinforcement. During the design phase, the obtained information allows to plan the building of an equally strong network and prevent dangerous and undesired situations. During the operation phase, it allows developing protection measures for minimizing damage to the power systems and economy caused by potential emergency situations. Sensitive places and their location will be identified with the help of numerical and analytical methods of studying the EPS’ scheme and parameters. For the steady-state modes, the generalized values are expressed via parameters of the nodal conductance matrix and Jacobi matrix of equations of the steady-state mode, which are the main sources of information about the sensitivity and heterogeneity of EPS in steady-state modes. The thesis is written in English language and includes an introduction, 3 parts, conclusions and a list of literature. The work consists of 140 pages and has 68 pictures and 16 tables. The list of literature includes 180 sources.