Methodology for the optimal design of transformerless grid-connected PV inverters

Abstract

The transformerless PV inverters are the major functional units of modern grid-connected PV energy production systems. In this paper, a new optimization technique is presented for the calculation of the optimal types and values of the components comprising a transformerless PV inverter, such that the PV inverter Levelized Cost Of the generated Electricity (LCOE) is minimized. The proposed method constitutes a systematic design process, which is capable to explore the impact of the PV inverter configuration on the trade-off between the PV inverter manufacturing cost and the power losses affecting the corresponding energy production. The design optimization results demonstrate that the optimal values of the PV inverter design variables depend on the inverter specifications, the technical and economical characteristics of the components used to build the PV inverter and the meteorological conditions prevailing at the installation area. Compared to nonoptimized transformerless inverters, the PV inverter structures derived using the proposed design optimization methodology exhibit lower manufacturing cost and simultaneously are capable of producing more energy into the electric grid system.

Analysis of Output DC Current Injection in Grid Connected Inverters

“…Therefore, inverters connecting a PV system and the public grid are purposefully designed, allowing energy transfers to and from the public grid. [1][2][3] Due to approximate short circuit characteristics of AC network, a little DC voltage component can accidently be produced by grid connected inverters which can create large DC current injections. If output transformers are not used, these inverters must prevent excessive DC current injection, which may cause detrimental effects on the network components, in particular the network transformers which can saturate, resulting in irritant tripping.…”

Single phase transformerless inverter topologies for grid-tied photovoltaic system: A review

“…Among a variety of renewable energy sources, PV is predicted to have the biggest generation, up to 60% of the total energy by the end of this century [7,8], because the energy which is converted into electrical energy is the light from the sun, which is free, available almost everywhere and will still be present for millions of years long after all non-renewable energy sources have been depleted [7,9]. Though the PV module is still expensive, due to the large-scale manufacturing it is becoming increasingly cheaper in the last few years.…”

Simulation of a-Si PV system linked to the grid by DC-DC boost and two-level converter

“…Modern power electronic converters have been developed for integration of renewable energy sources in the electric grid [9,10]. The power electronic converters, e.g.…”