Engelhart has begun marketing onshore wind farms equipped with Enercon wind turbines in the secondary control reserve market in the control zone of TenneT Germany. The activity started in early December 2025 and marks the first approval of an onshore wind farm pool for automatic frequency restoration reserve in the largest German control zone.
Automatic frequency restoration reserve is an automatically activated control reserve used to stabilise the electricity grid by restoring frequency to 50 Hz after short-term deviations. It operates after primary control has addressed the initial seconds following a frequency deviation and is later supplemented by manual frequency restoration reserve. These control reserves are activated by transmission network operators.
The system services have traditionally been provided mainly by fossil fuel-based power plants. According to the project partners, forecasting and control technology developed by Enercon and Gridfuse has enabled groups of wind farms to be controlled with comparable precision.
Since February 2025, Engelhart has offered flexibility in the manual frequency restoration reserve market with around 100 MW from 20 wind farms. Three wind farms operated by Looft-Schmidt in Huje, Schleswig-Holstein, with approximately 28 MW of flexibility, have now been transferred to automatic frequency restoration reserve marketing.
