Application of solid state transformers in utility scale solar power plants

Abstract

With the increasing participation of PV sources in the international energy market, more efficient inverter topologies and modules connections are desired. Large-scale PV plants (solar farms) use generally the central inverter topology, in which the PV modules are distributed into few maximum power point trackers. Although this topology has typically high efficiency, it has low MPP tracking performance. This paper proposes a modular converter based on solid state transformers (SST), in which high frequency transformers are used replacing the bulky medium-voltage line-frequency ones. In this technology, the converter output is provided by the series connection of the DC-DC-AC converter stages, supplied by independent PV module arrays. Among its many advantages, one can point out their reduced size and weight, improved reliability and easier maintenance of the system. This paper presents the proposed SST based converter topology for PV power plants and addresses some of its control issues.