Digital Modeling of Back-to-Back MMCs in Medium/High-Voltage Wind Power Generation Systems

Digital modeling plays a critical role in digital twin systems for back-to-back modular multilevel converters (BTB MMCs), enabling optimal design, condition monitoring, and lifetime prediction. This paper proposes a discrete-time digital model of BTB MMC system, including a power-circuit model and a loss-thermal model, to evaluate key performance indices such as voltage and current stresses, power losses, and junction temperatures of power devices. A generic modeling approach is developed to enable the flexible integration of different converter topologies, modulation strategies, and power device selections, allowing efficient evaluation of various MMC configurations. In addition, analytical formulations of system parameters are derived based on an explicit backward Euler method, eliminating iterative calculations and significantly improving computational efficiency. Simulation and experimental results validate the accuracy of the proposed model and demonstrate its superior execution speed compared with commercial simulation platforms and conventional digital models.