Convertible static transmission controller model and supervisory vector control for operation under unbalanced grid conditions

This paper proposes an electromagnetic transient model of the Convertible Static Transmission Controller (CSTC) system in shunt-shunt operation mode. This proposed transient model is used for dynamic analysis and system design. Two recently proposed control structures, which aim to suppress the DC link voltage oscillations under unbalanced AC grid, are applied and compared to the conventional state feedback control method. The simulation tests for a CSTC transmission system connect two active networks are adopted by PSCAD-EMTDC and MATLAB/Simulink. The results verify the validity of the mathematical model and the feasibility of the applied control strategies for the studied system under normal and fault/unbalanced AC conditions.