Stability enhancement of rectifier and DAB stages of SST model using dynamic phasor based PI controller

Abstract

Solid State Transformer (SST) is widely used in distribution renewable energy resources. SST includes AC-DC rectifier, DC-DC Dual Active Bridge (DAB) converter and AC-DC inverter. In this paper, continuous time average model and dynamic phasor model for combined Rectifier and DAB converter (R-DAB) are developed. Control scheme for R-DAB model is proposed for dynamic phasor based model, in which rectifier and DAB are being individually controlled using PI controller. The effect of controller has been analysed with change in input grid voltage variation. Stability analysis has performed using small signal stability analysis and Lyapunov's criterion. Developed model is verified with simulation in MATLAB/Simulink. Simulation result verifies the proposed modelling technique and controller performance.