Carrier Reconfiguration for Improving Output Voltage Quality and Balancing Capacitor Voltages in MMDTC-Based STATCOM

For Modular Multilevel DC-Link T-Type Converter (MMDTC)-based STATCOMs, under identical operating conditions, the submodule (SM) capacitor voltage ripple is inversely proportional to its capacitance value. A configuration with a lower capacitance will inevitably result in significant capacitor voltage ripples. During the PWM modulation process, these ripples can lead to distortions in the output voltage waveform. To address this issue, this paper proposes an innovative carrier reconfiguration method that not only compensates for the output voltage pulse deviation caused by SM capacitor voltage ripples but also achieves effective balancing of the SM capacitor voltages. Finally, the validity and performance of the proposed carrier reconfiguration method are verified through both simulations and experimental results.