The thesis consists of seven chapters. In the introduction to the basic features are given the power system, the problems of interruptions in electricity users at the interface between the transmission and distribution networks. Are given the basics of reliability and availability of components, systems, overview of indicators of reliability, methods of determining the reliability of the models of renewable and non-renewable components, the possible applications of Markov state space model and the basic functions of distribution and fault recovery, the second chapter. He briefly described the problems of reliability of man. The third chapter describes the basic pole diagrams in the Croatian power system, the organization managing the electricity system, the competence network center. A detailed review of the procedures prescribed by operational staff in disorders with interruption of supply. The fifth chapter describes the so far observed and analyzed the forced delays observed units and prescribed procedures for operational staff in the event of interruption of electricity supply. According to collected data on the intermittent supply of energy consumers in the four-year period determined by the distribution function and parameters of the function. The sixth chapter describes the proposed model to establish the user to supply electricity to the Transmission System Operator with respect of certain drive operations staff. Identified factors that are essential for the duration of interruption and consequently made models of execution. Markov model are shown two common conceptions of substations on the interface transmission, distribution network, taking into consideration the model of execution. The study included data on interruptions in the transmission network users and are compared with results of analysis of the expanded model. Based on confirmation of the model simulations were made for different duration of interruptions and the results of the analysis are given guidelines for improvement of certain procedures in order to reduce the duration. The final chapter offers a critical review of the issue of modeling the factors that influence the process of power supply following a disturbance to the basic guidelines for further research.