An Electromagnetic Transient Simulation Model of MMC-BESS for Various Operating Conditions

Existing electromagnetic transient (EMT) simulation models of the modular multilevel converter with an embedded battery energy storage system (MMC-BESS) often suffer from computational inefficiencies and difficulties in accurately simulating fault behaviors. To address these issues, this paper proposes an efficient EMT model for the MMC-BESS. The proposed model improves the detailed equivalent model (DEM) by accounting for the complex scenarios where both switches in the same leg are simultaneously turned off. The converter blocked state is simulated by incorporating auxiliary PSCAD switches and leveraging its built-in interpolation algorithms, while the battery disconnection is simulated by using supplementary decision formulas. Furthermore, a speedup calculation method is introduced to further optimize simulation efficiency. Evaluation of the proposed model is performed in the context of an HVDC system in PSCAD/EMTDC simulation environment, encompassing steady-state operation, transient responses, and faulted operating conditions. The results confirm the simulation accuracy and efficiency of the proposed model.