Kriegers Flak Combined Grid Solution - Real Time Power Transmission Control and Method for Transmission Capacity Calculation for Meshed Offshore Grids.

The Kriegers Flak Combined Grid Solution (KF CGS) is the world-first hybrid-asset system, which serves as an interconnection between East Denmark and Germany via the offshore wind power infrastructure in the Baltic Sea. The hybrid-asset system includes offshore wind power plants of both countries interconnected via a meshed offshore HVAC grids and an HVDC Back-to-Back Converter Station at German shoreline. The KF CGS interconnection is controlled by the Master Controller for Interconnector Operation (MIO). The MIO utilizes the optimal power flow (OPF) and performs the transmission capacity calculation applying wind power forecasts, equipment's electrical data, availability and ratings including dynamic line rating (DLR), and onshore grid limitations. Due to wind power forecast errors or trip of transmission equipment, the MIO mitigates overloading of any KF CGS equipment, which may occur, according to the prioritized rules with minimum possible wind power curtailment. This paper explains the method behind the transmission capacity calculations of the KF CGS hybrid-asset system, implementation of the simulation model for the grid-planning and grid-stability assessment, and presents the results of the MIO first onsite test. The lessons learned are useful for design and operation of future hybrid-asset systems combining both HVAC and/or HVDC interconnector offshore grids and wind power feeding into the same grid. [ABSTRACT FROM AUTHOR]