The UK’s National Grid Electricity System Operator (ESO) has released updated technical insights regarding the Holistic Network Design (HND) project, focusing on the integration of more frequent High Voltage Direct Current (HVDC) links into the primary transmission network. As of 12 April 2026, the strategy emphasizes the transition from point-to-point connections to a truly meshed AC-DC grid. This structural shift presents unique engineering challenges, particularly regarding the dynamic interactions between inverter-based resources and traditional synchronous generation.
The National HVDC Centre is currently spearheading research into “composite testing” of HVDC-connected offshore generation. This involves high-fidelity simulation and real-time testing of converter-rich networks to address issues such as sub-synchronous oscillations and low-inertia stability. The focus is now on the development of “Grid-Forming” (GFM) converters that can actively contribute to system strength and frequency regulation. Furthermore, the ESO’s roadmap highlights the necessity for advanced DC switchgear capable of isolating faults within multi-terminal HVDC systems without necessitating a total system shutdown—a critical technical hurdle for the reliability of future offshore wind hubs.
Source: The National HVDC Centre
