Performance of medium-voltage DC-bus PV system architecture utilizing high-gain DC-DC converter

The number of large-scale solar photovoltaic (PV) systems continues to increase, while the size of the largest systems has already reached several hundred megawatts. This trend will challenge existing PV system architectures and will require new PV system architectures with higher power ratings and higher voltage levels at the point of common coupling (PCC). This paper reports a medium-voltage (MV) dc-bus PV system architecture based on a high-gain soft-switched interleaved boost (SSIB) dc-dc converter. The interleaved characteristic increases the flexibility of the converter, allowing for either a higher voltage and/or current rating, thus increasing the power rating of the converter. The high-gain capability of the SSIB converter allows it to be connected directly to an MV dc bus. This will facilitate direct connection of a PV system to an MV ac grid (i.e., 20 kV) using only one step-up transformer. Simulation and experimental results are presented to verify the operation of the SSIB converter and to confirm the steady-state and dynamic performance of the proposed PV system architecture.