Assessment of the Star Connected Cascaded H-Bridge to be used in STATCOM application

The Modular Multilevel Cascaded Converters (MMCC) technology stands out as the preferred choice in modern High Voltage Direct Current (HVDC) and large Static Synchronous Compensator (STATCOM) applications due to its modularity, fault tolerance and high efficiency. Specifically, within the realm of MMCC, the Cascaded H-Bridge (CHB) configuration has become the preferred choice for STATCOM applications. Despite widespread adoption, there remains a lack of analysis and experimental validation regarding the ability of STATCOM to address imbalances during grid fault conditions, which is crucial for analysing its performance and operational range in grid applications. This paper aims to fill this gap by exploiting the Zero-Sequence Voltage Control (ZSVC) strategy for Single Star Bridge-Cells (SSBC) converter operation under both balanced and unbalanced grid conditions. The work will show the ability of SSBC-ST ATCOM to respond to imbalances even under severe grid faults.