Title: Evaluating System Stability and HVDC Dynamics in Vietnam's Integration of 3-5 GW Grid-Forming Offshore Wind
Authors: Ky Nguyen Thien, Ha Nguyen Manh
Volume: 10
Issue: 4
Pages: 38-47
Publication Date: 2026/04/28
Abstract:
Vietnam's rapid expansion of offshore wind under Power Development Plan VIII raises critical challenges for system stability due to low inertia, weak-grid conditions, and increasing reliance on inverter-based resources. Existing studies highlight the potential of grid-forming (GFM) converters and VSC-HVDC systems to support weak grids, yet no prior work has examined their combined impact within Vietnam's unique 110-500 kV network topology. This study develops a high-fidelity RMS-EMT simulation framework to evaluate the integration of 3-5 GW offshore wind via ±525 kV VSC-HVDC links under varying GFM penetration levels. Representative contingencies including a 500 MW generation trip, three-phase faults at major 500 kV buses, HVDC mode-switch events, and wind-power fluctuations were simulated across low-, medium-, and high-load scenarios. The findings suggest that the extent of GFM penetration can improve operational flexibility during and post disturbance. Nadir frequency improves from 49.37 Hz (GFL-only) to 49.74 Hz, and RoCoF increases from -0.68 to -0.28 Hz/s, and post disturbance recovery can occur in 0.5 of the time for all scenarios evaluated. Active power fluctuation can decrease from ~5 oscillations during GFM HVDC to over 110 % increase in inertia under voltage control (no oscillation). It shows that GFM FC HVDC provides integrated inertia on the system. Coordinated GFM implemented in conjunction with wind turbines and HVDC terminals created system synchronous support and seamless integration of large-scale offshore wind in Vietnam. GFM will need to be implemented in future grid and control system, HVDC designs and resource optimally system planning in Vietnam.