Performance Assessment of Three Phase NPC Based Grid Integrated Single Stage Solar PV System with Reduced DC-bus Capacitor

This work proposes an effective reduction in the capacitor size of the DC-bus of a conventional three-phase neutral point clamped (NPC) inverter-based grid integrated single-stage solar photovoltaic (PV) system. This has been done by implementing a metallized polypropylene film DC-bus capacitor instead of an electrolytic capacitor. As an outcome, this enhances the system’s long-term reliability, reduces cost, and increases the system’s life expectancy. The unbalance in capacitor voltage due to a small DC-bus capacitor is also identified. As a solution, a carrier-based modified modulation strategy is implemented to improve the dynamic response of neutral-point voltage. A single-stage solar PV array is utilized in this paper.

Index Terms—Solar PV array, DC-bus Capacitor, Grid-integrated inverter, Capacitor voltage balancing, Harmonic reduction.