Sub-modular Power Optimizers Based on Partial Power Converters for Utility Scale PV Plants

Abstract

Increasing the amount of energy extracted from a large-scale photovoltaic (PV) plant directly impacts its profitability. Obtaining higher energy yields depends heavily on the efficiency of the power conversion stages, but also on the configuration of the PV plant. More distributed maximum power point tracking (MPPT) among PV modules, allows maximizing the amount of energy extracted, especially under non-uniform conditions. To deal with partial shading conditions at module level, a sub-module power optimizer based on partial power converters is proposed. The configuration employs an isolated partial DC-DC power converters allowing to decouple the shaded parts from the unshaded at PV module level, maximizing the energy extracted. The behavior of the proposed configuration is verified through simulation, which is compared with a classic string configuration through analysis based on performance, improvements, and drawbacks of the proposed structure under mismatching scenarios.