Power Quality Improvement for PV fed NPC Converter for Grid-Tied Applications

This paper presents a single-phase neutral point clamped (NPC) multilevel converter (MLC) configuration for grid-connected photovoltaic (PV) applications. A single-stage control is implemented to feed PV array power to the grid at unity power factor. The direct and quadrature components-based controller is designed to have independent control on active and reactive powers injection. A low computational DC component injection based neutral point voltage (NPV) balance regulator ensures equal charging and discharging of DC-link capacitors. Moreover, the pulse width modulation technique with unipolar pattern is applied at lower switching frequency to adhere with minimum switching losses and power quality standards. The system performance in terms of parameters such as NPV balancing, converter voltage harmonics, the grid current harmonics, and unity power factor operation is analysed at variable irradiances. Simulation results are obtained using MATLAB/Simulink are validated using OPALRT test bench.