This paper presents a three-phase grid-connected photovoltaic generation system with unity power factor for any situation of solar radiation. The model of the PWM inverter and a control strategy using dq0 transformation are proposed. The system operates as an active filter capable of compensate harmonic components and reactive power, generated by the other loads connected to the system. An input voltage clamping technique is proposed to control the power between the grid and photovoltaic system, where it is intended to achieve the maximum power point operation. Simulation results and analyses are presented to validate the proposed methodology for grid connected photovoltaic generation system.