Low Voltage Ride-Through Capability of a Novel Grid Connected Inverter Suitable for Transformer-less solar PV grid interface

In order to face the challenges due to the large-scale integration of PV inverters on the distribution side, the grid connected Photo Voltaic inverters are expected to provide certain ancillary services in future. In this paper, the Low Voltage Ride Through (LVRT) that can be provided by a Cuk derived novel inverter topology, 6sw-CDTI, suitable for transformer-less grid-PV interface, is presented. With the help of single phase instantaneous p-q theory, the grid current reference is generated for LVRT. A feed-forward is added in the inverter control for improved dynamic response. Experimental results obtained from a 200W laboratory prototype, proved the LVRT capability under voltage sag condition without affecting the common mode voltage variation. This is highly advantageous for a transformer-less grid interface.