The increasing penetration of Renewable Energy Sources (RES) into transmission grids requires advanced reactive power compensation solutions to meet the stringent grid code demands. In this context, Static Synchronous Compensators (STATCOMs) have emerged as the preferred technology to ensure grid code compliance. Modular Multilevel Cascaded Converter (MMCC) topologies, especially the Single Delta Bridge Cell (SDBC) STATCOM, have become attractive options for high-power applications due to their modularity, scalability, and industrial maturity. Despite their widespread adoption, academic literature lacks systematic reviews that comprehensively address the integral design and sizing methodologies tailored to this topology, particularly regarding the translation of grid code requirements into hardware-level parameters. This paper addresses this gap by proposing a holistic framework for the design and sizing of SDBC STATCOMs. Based on this framework, this paper presents a critical review of the complete design process, synthesizing scattered literature into a coherent workflow. The analysis begins by translating international grid code requirements into converter performance specifications. Following this, the paper evaluates critical design choices for transformer coupling and insulation coordination. Furthermore, the paper critically compares existing methodologies for core converter dimensioning, including voltage sizing (number of submodules, DC capacitance) and current sizing (semiconductor stress, unbalanced operation). This review provides a unified reference for researchers and engineers, facilitating the optimized design of SDBC STATCOMs specifically tailored to enhance the stability of renewable-dominated grids.
