The final paper describes the operation of re - establishment of the power system after the breakdown, and the procedure of optimal restoration of consumer power supply. Accordingly, the properties of the power system, its stability, and algorithms for its re-establishment are described. The re-establishment of the system according to the principle of "bottom-up" is described on the example of the transmission area of Rijeka. For the proper establishment of PrP Rijeka, data on individual parts of the network were collected, the establishment of the system was simulated in the NEPLAN software package using the power flow function, and the division of the system into islands (island mode HPP Vinodol and HPP Senj). The theoretical basis for re-establishing the system in different ways is also described: - Bottom-up - Top-down - Build-Inward The problem that can occur when re-establishing the system is that the generator can be overloaded. This happens if the substations that are connected to the system are under heavy load. This problem is solved by unloading the system to a level appropriate to the conditions for reconnection.