Worked on the powsybl-core repository to deliver support for importing multi-terminal DC (MTDC) subnetworks from DGS files, enhancing HVDC converter modeling and data handling. Redesigned data structures in Java to enable deterministic traversal and efficient lookups for HVDC subgrids, and incorporated ground elements to improve network representation. Expanded unit testing coverage to validate new features and updated documentation to reflect changes in data structures and export order. Adjusted sign conventions and implemented unit conversion fixes to ensure HVDC data integrity and export reliability. Demonstrated a full stack development approach with a focus on robust documentation and maintainable code quality.