Multi-mode operation for the PV power system With SVPWM technique and PI with Fuzzy logic

A multilevel topology with medium-frequency ac
link for medium-voltage grid integration of utility photovoltaic (PV) plants is discussed in this paper. In the proposed system we approached perturb and observe (P&O) algorithm for MPPT to harvest maximum from the PV panel and to maintain the stability of the system. Each zone employs a mediumfrequency transformer with three secondary’s, which interface with the three phases of the medium voltage grid. An insulated-gate bipolar transistor full bridge inverter feeds the MF transformer. The voltages at the transformer secondary are then converted to three-phase line frequency ac by three fullbridge ac–ac converters. Cascading several such cells, a highquality multilevel medium-voltage output is generated. A new control method is proposed for the cascaded multilevel converter during partial shading while minimizing the switch ratings. Here we use Fuzzy controller for quick response time and accuracy in the secondary. The proposed topology eliminates the need for line frequency transformer isolation and reduces the dc bus capacitor size, while improving the power factor and energy yield.