Dual-Port Grid-Forming Interconnecting Power Converters in Hybrid AC/DC Grids

Interconnecting power converters (IPC) are the main elements enabling the interconnection of multiple high-voltage alternating current (HVAC) and high-voltage direct current (HVDC) subgrids. These converters can be classified either as grid-forming or grid-following. These roles can be assigned to both ac and dc terminals. This work compares state-of-the-art single-port grid-forming and grid-following control schemes with a dual-port grid-forming control scheme, which can simultaneously form a stable voltage on the ac and the dc sides. The dual-port grid-forming small-signal stability and dynamic behavior under fluctuations in the power flow are studied and compared against state-of-the-art control architectures. Moreover, the dual-port control scheme is validated and tested on a down-scaled laboratory platform with several transient events.