In this study we have addressed the problems that have to do with the running of the power system and the optimization of generation. We have treated the control of active and reactive power in order to keep the system stable condition. The objective of the control strategy is to generate and transmit power to a system composed of interconnection lines, in the most economical and safe methodology possible, keeping the voltage and frequency within norms. Also we gave the results of the simulation via Matlab of the dependency of the generator's electric parameters of an aggregate in the Vau-Dejes hydropower-plant versus the temperature of winding and oil of a power transformer of this aggregate.