Power Flow Analysis of On-Grid Photovoltaic Generation Using A Solid-State Transformer

This paper describes the power flow of a grid-connected PV system utilizing a Solid-State Transformer (SST). The SST system comprises a DC-AC converter, an isolated high-frequency step-up transformer, a bridge rectifier, and a Voltage Source Inverter (VSI). The DC-AC converter transforms the PV panel output voltage into a 5-kHz three-level square wave, where its pulse width regulates the PV load lines to generate power. The VSI delivers the PV power to the single-phase grid employing a grid current controller and a DC bus voltage controller. Computer simulation results verify the system's effectiveness in controlling the power flow from the PV panel through SST to the load and the grid while maintaining the grid current to be sinusoidal with a unity power factor, regardless of the presence of sunlight.