Leakage Current Elimination with Improved Non-Isolated Nine-Level Inverter for Grid-Connected PV Panels

Document Type: Original Article

Authors

1 Department of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran

2 Department of Electrical Engineering, Sahand University of Technology, Tabriz 51335, Iran

3 a) Department of Electrical and Computer Engineering, University of Tabriz, Tabriz, Iran, b) Engineering Faculty, Near East University, 99138 Nicosia, North Cyprus, Mersin 10, Turkey

4 Department of Electrical Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran

Abstract

In this paper, an improved structure with model predictive control (MPC) is presented to eliminate leakage current of grid-connected PV panels. The proposed topology consists of a PV panel in the input side, a non-isolated DC/DC multilevel boost converter and a nine-level inverter at the output side. The DC-DC multilevel boost converter can provide equal voltage levels in different rated power by controlling duty-cycle. The utilized dc-dc converter can increase the output voltage of PV panel to produce desired values at the input ports of the nine-level inverter. In Non-isolated grid-connected PV converters, there are parasitic capacitors between grid and PV panel which leads to the leakage current flowing through parasitic capacitors to the system. It causes a safety problem, injection of harmonic current to the grid, increasing losses, and efficiency reduction. In order to eliminate leakage current due to using the parasitic capacitor of PV panel, MPC control method is utilized to achieve high overall efficiency. To confirm the operation of presented structure and theoretical analysis, PSCAD/EMTDC software is used.

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