Automatic voltage regulation of the transformer units implemented in digital multifunction protection systems

The paper below present the main features of a digital multifunction protection system and of a voltage control function implemented in this kind of protection system, which control the voltage on the secondary side of a transformer. The paper also analyzes the functionality of a voltage control function included into a multifunction protection system of a 400/220 kV and 400 MVA power transformer unit from a transmission network. The simulation results relieve a prompt and secure action of the voltage control function, maintaining in tolerable ranges the voltage in the specified bus of the study network.