In Summer 2022, Mingjian interned with National Renewable Energy Laboratory (NREL) on a project to develop characterization methods and tools to evaluate reliability, transient stability, and economics of large-scale DC architectures in AC grids. Responsibilities of Mingjian for this internship include modeling multi-terminal HVdc and substations on transmission systems using a production cost model in PLEXOS. Advanced fast-acting control in HVdc substations are implemented for improved reliability, and corrective control of HVdc is investigated in multiple scenarios. In this project, they obtain the dynamic data of HVdc transmission line through simulation in Simulink and then incorporated the data into PLEXOS formulations. Sharing reserves through HVDC and its potential cost savings in WECC were also investigated. In addition, they tested N-1 SCUC model considering power oscillation damping (POD) control of HVdc in RTS-2016, and the proposed cases would be potential contribution to the future transmission system planning.