Silicium-Carbide-Based Isolated DC/DC Converter for Medium-Voltage Photovoltaic Power Plants

Abstract

The production of large-scale photovoltaics (PVs) is becoming increasingly popular in the field of power generation; they require the construction of power plants of several hundred megawatts. Nevertheless, the construction of these PV power plants with conventional low-voltage (LV) conversion systems is not an appropriate technological path. Particularly, large cross-section cables, a high quantity of semiconductors, and the bulky layout of 50/60-Hz step-up transformers make the PV system less competitive in terms of energy efficiency and cost. To overcome these drawbacks, this paper introduces new PV plant topologies with an intermediate medium-voltage direct current (MVDC) collector that requires galvanic isolation for connecting the PV arrays. Then, the design of a power electronic transformer (PET) is proposed, implementing 1.7-kV and 3.3-kV silicium carbide (SiC) power modules. The study confirms that this converter allows the use of medium-frequency (MF) transformers with high power densities while maintaining high efficiency, which facilitates the implementation of isolated medium-voltage (MV) topologies for utility-scale PV power plants.

Keywords

• SiC power modules
• solid-state transformer
• medium-voltage photovoltaic power plant