Power and Voltage regulation of a Solid-State Transformer based Quad-Active Bridge DC–DC Converter using Adaptive Linear Quadratic Regulator and Nonlinear Model Predictive Control

Solid-state transformer (SST) has gained increasing attention in the electrical grid. One of the SST architectures is a three stages SST where quadrable active bridge (QAB) can be used in the isolation stage. This work investigates power and voltage regulation of the QAB module-based SST design under unbalanced loading conditions. The proposed control system applied in the QAB implements an adaptive linear quadratic regulator (ALQR) and nonlinear model predictive control (NMPC) to achieve the regulation. The dynamic performance of the QAB based SST is proven analytically and supported by simulation results.