Electromechanical Transient Modeling of the Low-Frequency AC System With Modular Multilevel Matrix Converter Stations

This paper studies the electromechanical transient modeling of a low-frequency AC (LFAC) system with modular multilevel matrix converter (M3C) stations. Firstly, the mathematical model of the M3C and its equivalent circuits are established. Then, an iterative power flow calculation algorithm for AC systems integrated with the M3C-LFAC system is developed. The dynamic model of the M3C for electromechanical transient simulation is studied and implemented in PSS/E. Based on a test system consisting of two asynchronous AC systems with an embedded M3C-LFAC system, comparisons between the electromechanical transient simulation results from PSS/E and the electromagnetic transient simulation results from PSCAD are conducted. The results from PSS/E and PSCAD coincide with each other well, and the validity of the established electromechanical transient model is proved. Lastly, a stability study of a modified New England 39-bus system with an embedded M3C-LFAC system is executed, and the characteristics of the M3C-LFAC system are presented.