MMC Circulation Suppression Optimization Strategy Based on Quasi-$\text{PI}^{\lambda}\mathrm{R}$ Controller

To suppress the circulating current in modular multilevel converters (MMC), this paper analyzes MMC's operating characteristics and mechanism. Based on the poor suppression effect and slow adjustment time of traditional quasi-PR circulating current suppressors, a suppression method based on quasi-PI
^λ
R suppressors is studied. By introducing a fractional order integration link based on quasi-PR circulating current suppressors, the Whale Optimization Algorithm(WOA) was used to optimize the fractional order parameter
$\lambda$
to obtain the optimal value, while analyzing the stability of the system. Under the action of a quasi-PI
^λ
R suppressor, the second harmonic component was better suppressed and the adjustment time was shortened. And compare and analyze the system performance using traditional PR suppressors and quasi-PI
^λ
R suppressors respectively. Finally, the effectiveness of the proposed suppression method was verified through simulation.