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Abstract — This paper addresses the problem of providing frequency control services with offshore WF connected through a multi-terminal HVDC network. It proposes a control scheme such that offshore wind generators can provide inertia and primary frequency control to the grid. It consists of a cascading control mechanism based on dc voltage regulation at the onshore converters and frequency regulation at the offshore converters. The control scheme involves only local measurements and actions so that it avoids security and reliability issues of control schemes based on remote information. The effectiveness of the proposed strategy is illustrated in the case of two non-synchronous areas linked by a multi-terminal HVDC system connecting two offshor