Voltage and reactive power control for maximum utilization of a GW-size EHVAC offshore wind farm interconnection

The paper deals with the steady-state operation of a radial EHVAC cable transmission system with multiple power injection points, e.g. offshore wind farms, and variable shunt compensation. Generator voltages and variable compensation settings are determined by means of a power flow-based algorithm, aiming at symmetrical current magnitude profiles along individual cable lines (CLs): the proposed operation minimizes Joule losses and maximizes cable line (CL) exploitation. Network code constraints on the reactive power exchanged with the bulk power system are also considered. Successful application to a hypothetical 199 km long, 400 kV-50 Hz cable system collecting up to 2 GW from several OWFs is presented, showing that the proposed operation ensures at least 97% transmission efficiency at full load, with near-unity generator power factor values. Moreover, possible constraints due to sending end voltage rise at full load suggest the implementation of voltage control at the network connection point.