Doctoral thesis presents the main problems of existing control of normal and emergency operational conditions of interconnected power systems. The operation of existing automation is analysed from the point of view of elimination of active power deficiency or surplus. Drawbacks of existing automation as well as necessary improvements are revieled. New method for application of estimated active power deficiency or surplus value for control of normal and emergency conditions is proposed. Method is based on the usage of extended dynamics equation of considered power system to provide more accurate operation of automation during maintenance of normal operational conditions, as well as during control of emergency conditions. Research methodology and mathematical models are developed for various calculations of operational conditions and for analysis of proposed method. Application possibility of the proposed method is presented in various examples of power system structure and operational conditions, analysis and evaluation is given. Doctoral thesis is written in Latvian language, it contains 7 chapters, conclusions and recommendations for further work, list of references, and 2 appendices. Total amount is 163 pages, which include 74 figures and 8 tables. List of references includes 105 literature sources.