Models of hydraulic components based on impedance method have been implemented in a software called “SIMSEN”. This tool allows the simultaneous solution of the electrical, hydraulic, mechanic and control equations ensuring a proper interaction between the four parts of a system. In this paper the interaction between hydraulic and electric part of 2 Francis turbines power plant is investigated by comparing the simulation results obtained with and without coupling hydraulic and electric phenomena. Using hydraulic, electric and hydroelectric simulation models, total load rejection, earth fault, out of phase synchronization and load variation have been investigated. Hydroelectric simulations offer the advantage to enable to study the coupling of hydraulic and electric parts and to optimize regulators parameters in interconnected mode.