An interfacing circuit using a biased saturable transformer for photovoltaic and alternative energy system with protection against the line fault

摘要

A simple circuit consisting of two saturable transformers for interfacing an alternative energy system to the utility grid is proposed. Each transformer has two windings, each one is connected in series and same polarity, and the other is connected in series and opposite polarity, respectively. This circuit has the inherent properties not only of isolation but also of spontaneous disconnection at the time of line fault. The quantity and direction of transmitted power are controlled by the phase lead angle of the inverter voltage to the utility one. The maximum power transmission from the DC source occurs when setting the phase inverter by 135/spl deg/ in lead, and this angle is independent of the inverter output voltage and load resistance. This high-frequency link scheme is effective for practical applications.