Hybrid design of active and passive strategy to suppress high-frequency resonances of MMC-based system

In recent modular multilevel converter (MMC)-based projects, high-frequency resonance (HFR) incidents have posed severe threat to the grid security. Although the active methods have been suggested, they cannot completely eliminate the HFR risk of MMC system. The hybrid method, i.e., combining the active and passive ones may be a solution to solve the HFR problem. However, the existing hybrid methods introduce additional loss. To inhibit the HFR and reduce the loss of passive devices, a hybrid active and passive strategy is proposed. Compared to existing hybrid methods, it can effectively reduce the loss introduced by passive devices. Additionally, the parameters matching relationship between the damper and the low-pass filters is revealed, and a hybrid design approach is proposed to achieve the above goals. Finally, electromagnetic transient simulations are performed to validate the correctness of the parameter design and the effectiveness of the proposed strategy.