This paper presents the modeling, simulation and analysis of the dynamic behavior of a hydroelectric power plant of 2x343 MVA including hydraulic system, electrical installations, rotating inertias and control systems. First, the modeling of the electrical and hydraulic systems is described. The electrical system is constituted by a salient-pole synchronous generator with its ST1A excitation system model and PSS2B power system stabilizer model. Then, the set of parameters of the turbine speed governor of the hydroelectric power plant is determined with a specific identification procedure to achieve stable operation for different cases as interconnected or isolated operation. The analysis of the stability of the power plant is investigated through time domain simulations for different sets of controllers’ parameters and for different cases (simulation of the only electric part and of the whole hydroelectric system).