PQU diagram capabilities and operational needs for offshore HVDC converter stations

In this paper we explore the PQU requirements of the offshore HVDC converter used to connect offshore wind farms. In such application the offshore network is well defined and simply adopting the same requirements as onshore would result in the oversized HVDC converter and non-optimum design. For the offshore AC network, the offshore HVDC converter is responsible for setting up the AC network by providing AC network frequency and maintaining AC system voltage at PCC. To achieve this, it is normally operated as a voltage source such as a fixed AC voltage is produced at the valve or converter terminal. Once wind turbines are connected to the network they can provide reactive power support at PCC. In general, each wind turbine string can typically compensate for the cable capacitance at the…