Enhancing the frequency control of the Simris Local Energy System.

Within the Swedish demonstrator in the village of Simris, E.ON sets up a local energy system, where wind and solar energy generation, in combination with central batteries, local customer involvement and an innovative management system provide islanding capabilities. In the early stage of the demonstrator, one central Li-ion battery was employed to provide grid stability.

A second battery has been added to the system recently: E.ON made the choice of the redox flow technology. The flow battery is used for two main reasons:

  1. To increase the islanding duration;
  2. To enable frequency dependent testing.

The increased performance in islanding gives us the possibility of doing island-testing while reducing  the need for the biodiesel backup generator.

The battery enables islanding for approximately 2 hours on (flow) battery power alone during maximum load.

Frequency dependent testing means that, by putting the flow battery in a frequency dependent mode, we can support the frequency in the microgrid by responding directly to the measured frequency, minimizing frequency variation within the microgrid and demonstrating how systems could autonomously support the power balance in a microgrid without a central controller.