Power Decoupling Control for V2G/G2V/PV2G Operation Modes in Single-Phase PV/Battery Hybrid Energy System with Low DC-Link Capacitance

Abstract

Three-port intelligent conversion systems, interfacing photovoltaic (PV) arrays and electric vehicles (EVs), with an electrical grid, are a promising flexible infrastructure for future smart grids. In this system, multi-energy, direct current (DC), and alternating current (AC) power are decoupled by a larger DC-link capacitor. However, bulk capacitors prevent the achievement of high power density and high reliability of this system. To address this issue, active power decoupling control for a single-phase three-port conversion system is proposed in this paper. Owing to its low internal impedance, the inherent double-line-frequency ripple power in a single-phase system can be actively absorbed by a Li-ion battery pack, with a sinusoidal charging/discharging technique, in the proposed control strategy. Therefore, the capacitance of the DC-link capacitors can be significantly reduced. Further, a DC-link voltage ripple resonant compensation control loop was developed to ensure single-phase ac power quality on the grid side. Finally, the experimental results obtained from a 2.5 kVA single-phase three port power conversion prototype verify the feasibility and performance of the proposed control strategies.