Grid-Tied Neutral Point Clamped based Centralised Photovoltaic Inverter with Improved DC Link Voltage Balancing and Harmonic Minimisation Control
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Indian Institute of Technology Kharagpur
University of Illinois at Urbana-Champaign
Supratik Bhowmick   

Indian Institute of Technology Kharagpur
Power Electronics and Drives 2021;6 (41):185–203
This paper proposes an improved space vector pulse width modulation (SVPWM) based DC link voltage balancing control of a three-phase three-level neutral point clamped (NPC) centralised inverter supplying the generated power from PV array to a three-phase utility grid. Two possible schemes have been developed based on the power conversion stage between PV array and the utility grid namely, two stage (three-level boost converter + three-phase three-level NPC inverter) and single stage (three-phase three-level NPC inverter alone). The comparison between these two schemes has been thoroughly discussed in terms of the control strategies employed, power loss analysis and efficiency. The performance of the centralised inverter under different modes of operation has been investigated by developing the required control strategies for smooth operation. Using the proposed control strategy, the centralised inverter can be operated as a static synchronous compensator (STATCOM) during night time, if needed. The power loss incurred in the power-electronic converters has been analysed for constant and also for variable ambient temperature. The effectiveness of the centralised inverter as an active filter (AF) has also been verified when a three-phase non-linear load is considered in the system.