Principles of Operation of Grids of DC and AC Subgrids Interconnected by Power Converters

The concept of segmented AC power systems interconnected by means of HVDC is becoming more and more significant for many cases worldwide. Such systems already exist and will become more complex with the increasing emergence of HVDC links and grids. The concept of a grid composed of multiple subgrids motivates the need to define the governing roles of Interconnecting Power Converters (IPC) which connect the different subgrids. Such IPC can have various operation modes which are presented and analyzed in this paper. In addition, the principles of operation needed for each individual subgrid and for the overall system are introduced and discussed. The resulting fundamental equations are outlined and combined in a power flow formulation of the overall system. A simple case study is presented to illustrate the power flow formulation in a grid of multiple subgrids, also introducing example dynamic simulations of transitions between different operating points.

Automated summary

The paper discusses the increasing significance of segmented AC power systems interconnected by HVDC, and the need to define the governing roles of Interconnecting Power Converters (IPC) connecting different subgrids. Various operation modes of IPC are presented and analyzed, along with principles of operation for each subgrid and the overall system. Fundamental equations are outlined and integrated into a power flow formulation, with a case study illustrating the power flow formulation and dynamic simulations of transitions between operating points in a grid of multiple subgrids.