This thesis gives a short and complete overview on the influences of distributed sources on electrical power system based on generation of electrical power. First, the basics of electrical power system and generation network are presented and after that a description of electrical power system management is given. In the third chapter are described distributed sources, distributed generation of electrical power, allocation and technical conditions for connection of distributed sources on the distribution network, and the influences of distributed sources on the generation and transportation systems. In the fourth chapter a simulation of influences of distributed sources on a radial network is given. The positive and negative influences of distributed sources on a radial network are considered, and the influences on losses and voltage opportunities when the network is not under heavy load.