Model Predictive Control of a Packed-U-cells Inverter with PV, Boost and Bidirectional Rectifier for Solid-State Transformers

Balancing the power flow in a three-phase system is one of the challenges in distribution networks, which is even more exacerbated with the widespread adoption of renewable energy sources (RES) and the development of smart grids. The transformer is one of the fundamental devices in power distribution that provides a means to link high-voltage, medium-voltage, and low-voltage networks in addition to galvanic isolation. Classical transformers utilize magnetic coupling with a turn ratio between coils to achieve this basic functionality, but they are bulky, expensive, and do not provide additional smart features. The use of a power electronics transformer (PET), also called a solid-state transformer (SST), has been introduced in the literature using a three-phase to single-phase converter to solve this problem. However, the focus was mainly on the inverter and a basic diode rectifier was used without RES integration. This paper bridged this gap by replacing it with a bidirectional converter and investigating its performance using solar power connected to the DC-link of the three-phase to single-phase solid-state transformer. The bidirectional SST was verified using simulations and the results show that the SST is able to maintain the balance between the three-phase system and the integrated renewable sources while providing bidirectional power flow with high efficiency and low Total Harmonic Distortion.