IGCT in HVDC Transmission: Hybrid Commutated and Modular Multilevel Converter

High-voltage direct current (HVDC) transmission is expanding globally to integrate utility-scale renewable energy sources. Historically, the line-commutated converter (LCC) has been the preferred technology for long-distance, high-capacity transmission because of its thyristor-based operation, which offers simplicity, efficiency, and reliability. As a result, LCCs are particularly effective for transferring bulk power from remote generation sites to urban centres. Voltage-source converter (VSC) HVDC technology has been increasingly deployed, especially after the invention of modular multilevel converter (MMC) technology. They have been deployed across various system topologies, from point-to-point, back-to-back, and multi-terminal HVDC systems. VSCs’ ability to independently regulate active and reactive power is crucial for maintaining stable grid operation, as grids are increasingly exposed to variable renewable generation. VSCs’ ability to provide fast power-flow control and supporting grid-forming or black-start capabilities is essential for integrating wind, solar, and other intermittent resources into modern power systems.