Coordinated voltage and reactive power control scheme of HVAC meshed offshore grid of offshore wind power plant at Kriegers Flak

The Kriegers Flak Combined Grid Solution (KF CGS) is the first hybrid-asset project utilizing an offshore HVAC/HVDC interconnector through already established and under-commissioning large offshore wind power plants between East Denmark and Germany in the Baltic Sea. In total, the KF CGS utilizes above 520 km HVAC cables, and, in the Danish side, above 200 km 220 kV cables arranged into a meshed offshore transmission grid. As the cables approach critical lengths, the reactive power generation is dependant on the active power transfer. In the Danish side, the control is realized by an automatic voltage and reactive power control (AVR/RPC) of several switchable and variable reactors and transformers with tap-position controllers, and the Wind Power Plant Controllers (WPPC). In the German side, the voltage control is achieved by the HVDC Back-to-Back and WPPC and part of the Optimal Power Flow (OPF) by the Master Controller for Interconnector Operation (MIO). This paper introduces the overall control of the KF CGS and presents the proposed coordinated voltage and reactive power control and assets on the Danish side of the KF CGS interconnector.