Efficient PV Grid Integration Using a Three-Level NPC Converter and Advanced Control with Phase Disposition PWM

This paper presents an innovative approach to photovoltaic (PV) grid integration using a single three-level neutral-point clamped (3L-NPC) converter with an advanced control employing a nonlinear control technique and Phase Disposition Pulse Width Modulation (PD PWM). Unlike conventional systems that utilize separate DC-DC and DC-AC converters, this study proposes a unified control strategy to regulate DC voltage and ensure unitary power factor correction (PFC) at the grid side. The DC voltage reference is generated by a Perturb and Observe (P&O) Maximum Power Point Tracking (MPPT) algorithm, optimizing the extraction of maximum power from the PV array.

The methodology includes detailed modeling of the PV system, the 3L-NPC converter, and the proposed control algorithms. The PD PWM technique is implemented to improve the harmonic performance and voltage balancing of the converter. Simulation results, conducted in MATLAB/Simulink, demonstrate the effectiveness of the proposed control strategy in maintaining stable DC voltage and achieving unitary PFC under varying solar irradiance. The results show significant efficiency improvements and reduced total harmonic distortion (THD) compared to traditional methods. In conclusion, the integration of MPPT and PFC in a single 3L-NPC converter presents a cost-effective and efficient solution for PV grid integration. The proposed system enhances overall performance and reliability, paving the way for more streamlined and sustainable renewable energy systems.