Autonomous frequency smoothing control of offshore wind-linked HVDC for low-inertia system

•Modeling and analysis of offshore wind-linked HVDC control.•Offshore wind-linked HVDC participates in onshore frequency control using local measurements.•Stability trajectory analysis according to control parameters and system frequency response analysis.•Adaptive gain for sustainable frequency regulation considering energy headroom and status.•Effectiveness was validated through simulations in various scenarios that relief of synchronous generators burdens.