In December 2020, the Kriegers Flak Combined Grid Solution (KF CGS) was inaugurated by the transmission system operators 50Hertz, Energinet, the German Federal Minister of Economics and the Danish Minister for Climate, Energy and Utilities. The system is used as a "hybrid system" to transport wind power from the four offshore wind farms (Baltic 1 & 2, Kriegers Flak A and B) to the land and to promote energy trade between Germany and Denmark.
At the heart of the connection of these two energy grids through the Baltic Sea there is a Master Controller for Interconnected Operations (MIO). The solution is based on a cutting-edge technology, including a geo-redundant system coupling ABB AbilityTM OPTIMAX®, System 800xA and Symphony Plus Historian.
Enabling smart operations and optimizing energy flows
MIO has been developed to calculate the available capacity of the interconnector in real-time and up to 72 hours in advance to control the power exchange between the two countries. This enables operators to maximize the input of highly valuable green wind power into the two national grids which operate on different voltage levels and asynchronously.
This is a highly critical task, since a failure can lead to a sudden drop of up to almost 1 GW of power. OPTIMAX®, as the operational kernel of MIO, acts as the heart and brain not only avoiding these critical drops, but also maximizing the utilization of green wind power, substantially increasing power flows between Germany and Denmark. In this way, carbon free energy can be used in places where it is needed the most and transmitted between countries. This is an important step towards a sustainable energy system across Europe.
“MIO is the first brain of an offshore grid and might become a blueprint for operating hybrid offshore grids around the world. Optimization of real time system operation as well as operational planning is key to maximize the use of offshore equipment as well as to maximize harvested wind energy” said Dr. Anne-Katrin Marten, 50Hertz project manager.
A Cutting-Edge Technology to develop a unique project
Every 5-seconds, MIO sends new active power and voltage setpoints to the HVDC converter and, if necessary, to the wind farms. Calculations are based on real-time measurements from the transmission grid. In addition, MIO calculates capacity forecasts for the offshore interconnection up to two days in advance.
Map (source: 50 Hertz) 
Source: 50Hertz 
Source: 50Hertz
The development of the optimization algorithm took place in software-in-the-loop tests. A simulation tool was coupled with the MIO system via a real-time interface. This made possible to examine hundreds of test cases in advance and to fine-tune the algorithm. In addition, the customer received the MIO algorithms as a Docker software container to perform further simulations before final implementation.
"The Kriegers Flak Combined Grid Solution has been a great achievement from a technical point of view. The strong synergy and close collaboration across all teams were key factors to succeed. Here we have reached another milestone in our OPTIMAX portfolio. No comparable project has been implemented anywhere in the world. ABB has risen to the challenge of this complex offshore/onshore connection with its cutting-edge technology”, said ABB Project Manager Sonja Tauer.
