Modeling and Analysis of DC Side Disturbance Level of Star Cascaded STATCOM Under AC System Disturbance

Star cascaded STATCOM is prone to DC side voltage instability when AC system fails. In order to analyze the disturbance level of the DC side voltage under AC system disturbance, this paper establishes a mathematical model based on the analysis of the current inner loop and the power module, AC side input admittance and DC side input impedance of STATCOM. Furthermore, a closed-loop transfer function from AC side voltage disturbance to DC side voltage disturbance is established. The experimental results based on different system voltage feedforward control strategies show that this method can accurately realize the analysis of the DC side voltage disturbance level under AC system faults.