Research on operation characteristics of power system in sub-group network and site-division construction

Focusing on the characteristics of concentrated distribution and large coverage area of renewable energy in inland regions, this study aims to explore methods to reduce AC electric distance. Firstly, a novel UHVDC topology based on sub-group network and site-division construction is proposed, which optimizes power transmission efficiency and stability. The corresponding control strategy under this topology is introduced to ensure coordinated operation between converter stations. Then, the imbalance characteristics in the site-division construction scenario are analyzed, proposing an imbalance current suppression strategy suitable for the system under the constraints of DC line losses and submodule capacitor voltage balance. Finally, through establishing typical scenarios for case analysis, a HVDC transmission system model with positive and negative pole site-division construction is constructed in PSCAD/EMTDC. The simulation results validate the effectiveness of the proposal. This research provides a feasible solution for integrating large-scale renewable energy into power grids with improved transmission performance and operational reliability.