50Hertz and ENERTRAG test reactive renewable power for the grid

50Hertz and ENERTRAG test reactive renewable power for the grid
Employees in a 50Hertz substation: Reactive power ensures smooth electricity transport. Image courtesy 50Hertz/Jan Pauls.

German TSO 50Hertz and ENERTRAG SE, an operator of renewable energy plants, have launched a joint pilot project near Bertikow in Brandenburg, Germany, to provide reactive power to the grid through renewable energy.

At Bertikow, wind turbines and other renewable generation systems with a total capacity of over 500MW are connected to the nearby 50Hertz substation. Through the project and in the future, they will provide the reactive power necessary for voltage stability, and thus overall grid stability, even when little wind feed-in is available.

Reactive power, states 50Hertz, ensures the smooth transmission of electricity over long distances. It can be used to compensate for voltage losses during transmission so that as much active power as possible reaches the consumer and the grid functions safely and reliably.

Until now, reactive power has mainly been provided by conventional power plants while in operation. Under current regulations, renewable energy plants do not have to deliver reactive power in periods when they provide less than 10% of their active power.

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50Hertz highlights how this presents a challenge for power grid operators as they have to compensate for the necessary reactive power with other technical systems in order to maintain voltage stability at these times.

However, modern wind turbines are also technically capable of providing reactive power, even when there is little or no wind.

In the pilot project, ENERTRAG and 50Hertz want to test how reactive power activation works technically in practice and can be contractually designed, including with a view to a future reactive power market.

“Innovative solutions for reliable power grid operation are absolutely vital for the energy transition,” said Dr Dirk Biermann, chief markets & system operations officer at 50Hertz. “At 50Hertz we’re testing a range of options.

“The permanent provision of reactive power by renewable energy plants is new technological and regulatory territory. Grid operators at the distribution system level, where the majority of renewable energy systems are directly connected, will therefore also benefit from the insights we’re acquiring here.”

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“In the context of the energy transition, renewable energy systems will have to fully provide the system service that is currently still supplied to the grid by conventional power plants,” added Thorsten Leske, head of electrical grids at ENERTRAG.

“In the pilot project, different renewable energy systems will supply reactive power to stabilise the transmission grid, even when there’s no wind. At the same time, this is an example of subordinate distribution grids in which the technical possibilities of renewable energy systems haven’t yet been fully exploited. The next step should be to establish a market model for the provision of reactive power.”