'Black start' with wind power: Rostock power plant successfully started up via cable Germany - Denmark"

The Combined Grid Solution (CGS), the recently inaugurated interconnector between Germany and Denmark, was used as a 'starting aid' to fire up the power plants turbines. To achieve this, the Rostock power plant was initially first completely separated from the German power grid. Subsequently, the Danish system operator Energinet provided the required 380-kV voltage via the CGS and the newly constructed converter systems in the substation in Bentwisch near Rostock. The CGS is a hybrid system with a capacity of 400 MW that transmits electricity between both countries. The two wind farms Baltic 1 and Baltic 2 are also integrated into the CGS and supply electricity to the 50Hertz transmission system. In 2021, Kriegers Flak wind farm will be connected to the Danish transmission System.

Dr Dirk Biermann, Chief Markets and System Operations Officer (CMO) at 50Hertz: "This successful start-up attempt illustrates the importance of cooperation at European level in the age of renewables. In close cooperation with our Danish colleagues, the system management departments of Energinet and 50Hertz have demonstrated their capacity for innovation as well as their level of professionalism."

Dr Frank Golletz, Chief Technical Officer (CTO) at 50Hertz: "Several technical innovations were implemented in the Combined Grid Solution project. The back-to-back converter in the Bentwisch substation plays a key role here, as it synchronises and connects the two asynchronous power systems of Denmark and Germany. The successful start-up attempt was, therefore, also a practical test for this highly complex converter."

Rainer Allmanndsdörfer, Chef Executie Officer (COO) at Rostock power plant: "We are extremely pleased that we could support this important test. The black start test has impressively shown the important and central role that the power plant location Rostock with its available capacity plays for the security of supply in northeastern Germany."

Start-up attempt are part of the grid restoration plans of transmission system operators. Their capability has to be tested regularly in their corresponding grid areas to guarantee the swiftest possible restoration of the electricity grid after a power outage. Traditionally, storage or gas-fired power stations are used, because they do not need external power sources to start up. This for instance includes pumped storage stations with hydro power. Other thermal power stations are usually not 'black start capable' without a powerful external power source, as they already need a lot of energy to start up.