Modelling of electronic power transformer and its application to power system

Mathematical models of an electronic power transformer (EPT) are established for steady-state and transient stability investigations. To simplify oscillation damping analysis, a simplified dynamic model is developed by neglecting transients of a high-frequency transformer and filter inductors. Comparison between the simplified dynamic model and the detailed model is carried out by simulations using numerical computation and Matlab/Simulink to verify the accuracy of the developed model. For the purpose of the EPT controller design, a small-signal model of the EPT in a d-q synchronous rotating reference frame is established by linearisation about the operating point. According to the developed models, linearised Phillips-Heffron models of the power systems installed with the EPT are presented. Afterwards, as a case study, based upon the Phillips-Heffron models, the damping function of EPT is discussed and its performance is verified by numerical simulation.