Performance evaluation of a new control scheme of distributed two-stage PV conversion system using three levels voltage source inverter for stand-alone application

In this paper a distributed two-stage photovoltaic system using three levels inverter for stand-alone application is treated. The maximum power point tracking based on the “perturb & observe” (P&O) approach as a control strategy of the two boost DC-DC converters is applied. In order to get the best AC voltage waveform, the space vector pulse width modulation technique is used in this paper. To maintain the two capacitors voltages of DC bus equal, a new algorithm using the load, capacitors and boost converters currents is introduced to control loop. Without introduced any system to regulate the fluctuation of the DC bus and to get a stable output inverter voltage, authors in this paper propose a proportional regulator of inverter modulation index. A theoretical analysis with a complete simulation of the system with different profiles of irradiance for each DC/DC converter is presented to prove the excellent performance of the proposed technique.