Germany: Fraunhofer IWES Scientists to Develop New Method to Set Operating Reserve

In cooperation with the transmission system operator TenneT TSO GmbH, scientists from the Fraunhofer IWES intend to develop a new method to set the operating reserve on a daily basis.

The advantage of this new method is the possibility to include forecasts, e.g. for the power input for wind energy and photovoltaics. With this, setting the operating reserve becomes more reliable and efficient, particularly for those electricity systems with a great amount of renewable energies. The research project runs from March 2013 to February 2015 and is supported by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety.

The transmission system operators (TSO) are responsible for a secure and reliable network operation. This includes maintaining frequency stability which is done by minimizing the imbalances between production and consumption with the help of the operating reserve. The operating reserve is divided into primary reserve, secondary reserve and tertiary reserve and these differ, inter alia, in their activation time (30 seconds, 5 minutes and 15 minutes). The essential question is how to set the operating reserve.

The amount of primary reserve for Europe is set by the ENTSOE (European Network of Transmission System Operators for Electricity). The secondary reserve und tertiary reserve in Germany is set on a quarterly basis by the TSO and which is modified by the Graf-Haubrich-method. The idea behind the Graf-Haubrich-method is that any different forecast errors leading to an operating reserve are combined to a total reserve distribution.

This distribution is used to set the operating reserve. A disadvantage of this method is that the fluctuating power feedin of wind and solar power leading to different amounts of operating reserve is not considered.

“Besides developing renewable energies, it is essential to adapt the network operation for the success of the Energiewende”, emphasizes Kurt Rohrig, Head of R&D division Energy Economy and Grid Operation at the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in Kassel.

Setting the operating reserve on a daily basis, taking the avail-able forecasts for the next day into consideration, could lead to a substantially lower operating reserve. “The costs of secondary and tertiary reserves were around €476 million throughout Germany, so we believe there is a huge potential for savings”, says project manager Markus Speckmann of Fraunhofer IWES. In addition, critical situations such as in early 2012, when low temperatures led to an increased operating reserve, can be avoided by recognizing them at an early stage and provide op-erating reserve at the appropriate time, thus improving grid stability.

Therefore the project consortium, consisting of Fraunhofer IWES und TenneT TSO GmbH, intends to develop a method for setting secondary and tertiary reserves on a daily basis. In order to determine the share of the secondary and tertiary reserves in the total reserve, an automated decision for calling up the ter-tiary reserve is developed. Furthermore, the forecast errors of different categories of balancing groups are analyzed. These have a crucial influence on the balancing energy und thus indi-rectly on the operating reserve.

[mappress] Press release, June 24, 2013