Neutral Point Voltage Balancing Control and Quality power Improvement of PV System Based on Dual Three-level Stage Conversion

This paper presents an overall control approach for a grid connected photovoltaic (PV) system based on three-level DC-DC boost converter (3LBC) on the front of a three-level t-type inverter (3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> I) acting as active power filter. The neutral-point (NP) voltage balancing is ensured by a new control strategy applied for 3LBC; this avoids the need to change the conventional three-level space vector modulation (SVPWM) algorithm or to add additional components. The capability of the proposed system to control the current injected into the grid, compensate the harmonics and the reactive power demand, and also guarantee the DC-link capacitors voltages balancing is demonstrated through variety of simulations.