The fundamentals of the calculations of the optimum regimes of electrical systems and thermal power plants are considered. The basics of the mathematical apparatus needed to make the calculations is included. Practically all the modern optimization methods of electrical systems with and without hydropower plants are described. The possibilities are shown how to observe the impact of limitations on the regime parametres in case of similarities or dissimilarities. The book also considers the impact of the accidental factors on the regime optimization and decision making. The probable models of economically independently functioning electricaal systems are included. A separate chapter is devoted to the dynamic programming method which is widely used in power engineering in the calculations of regime optimisation and solving the tasks of the development of electrical systems. The included material on the fundamentals of the artificial neuron networks will allow the reader to get acquainted with a new, nontraditional approach to solving tasks in electrical power engineering, especially, in the optimization of the power system regimes when choosing the operating equipment / strādājošo iekārtu sastāvu. The theoretical conclusions are illustrated with examples.