Thesis describes the rated voltage, its meaning and the problems that can happen with a voltage (voltage drop). Describes the regulation in certain elements of the network with a special focus on the phase shifting transformers (PST). Voltage regulation can be made to various elements in the network: - on-generator excitation changes: - on transformer (change the number of turns); - on water (change the water parameters); - on consumer (change of reactive power). The describes the relationship between voltage and reactive power. Use the program to simulate power flow angle change in voltage transformer observed what was going on with the network, and came to the conclusion that the step angle regulating the transformer should be as small as possible.