A Multi-level Inverter Based On-load Tap Changer Transformer Topology for Harnessing Photo-voltaic Energy

In this paper, a new topology is proposed in which the electro-mechanical tap changing arrangement is replaced with a variable voltage ac source derived using a multi-level converter transforming photovoltaic (PV) generated dc voltage. The multilevel inverter circuit substitutes the change-over switch in the conventional configuration of tap changer transformers. In addition to being a point for connecting the PV source, the arrangement also improves the OLTC operation by eliminating the change-over switch transient and the need for the tie-in resistor. To demonstrate the viability of the proposed system, an existing topology of a five-level multilevel inverter is employed in the PLECS software. The results proved that the proposed structure is capable of maintaining the load voltage at the desired value.