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© Gerhard Hirn, BINE Informationsdienst
Communications technology reduces the voltage fluctuations
Projektinfo 12/2012

Fig. 1: Total decentralised generation in the Trier region (three rural districts, in total 3,900 km²: Bitburg-Prüm, Bernkastel-Wittlich and Trier-Saarburg). Depicted is only the decentralised generation fed into the medium and low voltage range.
© RWE Deutschland

Fig. 2: Investigated voltage regulator in the low-voltage grid (above) and voltage regulator in the medium-voltage grid (below).
© RWE Deutschland
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Smart regulation of rural electricity grids

In the “Smart Country” model project, researchers in Bitburg-Prüm were testing out the distribution network of the future. It is designed to respond flexibly to the increasingly decentralised generation of renewable electricity in the grid. For this purpose various operating resources were further developed: an optimised biogas plant, which controls the electricity supplied by the grid, virtually stores surplus electricity with an efficiency of 98 %. In addition, voltage regulators double the usable output capacity in the grid. The Eifel project successfully passed the field test after around one year.

The existing electricity grid is not designed for the diverse manner of ways in which electricity is fed into the grid. This particularly applies to rural areas. Because of the many decentralised grid injections and low local requirements, new grid solutions are necessary in order to meet future requirements. New distribution grids – so-called Smart Grids – will provide the basis for sustained energy use. However, how these intelligent grids will (or should) actually look like is still not clear. With traditional electricity provision, the electricity only flows in one direction: from the power plant to the customers. With smart grids, there are additional small power plants. Wind turbines, solar power installations and biogas plants generate additional electricity that is fed into the grid. Because the energy is not constantly generated, this causes voltage fluctuations, particularly in rural electricity distribution grids.


The aim of the “Grids for Future Electricity Supply” research project (“Future Grids / Smart Country” for short) was to develop and demonstrate innovative grid concepts as a basis for smart grids and provide an economic and technical analysis of them. “All measures are aimed at enabling more decentralised generation in the existing grid,” explains Torsten Hammerschmidt, head of the research project. The investigated grid concepts consider an increased use of information and communications technology (ICT) as well as intelligent secondary technology. There are also new components analysed, ranging from voltage regulators based on power electronics to approaches utilising flexible supply voltages in the grid, for example by providing the permissible voltage range for customer devices with inverters at house connection points. The construction of intelligent grid expansion is also indispensable for connecting decentralised generators, whereby the focus of the project ranged from the distribution grid to the customer connection. Together with plant manufacturer ABB, the consultancy company Consentec and the Technische Universität Dortmund, RWE Deutschland tested the first smart grid in Germany of this kind in the Eifel region of Bitburg-Prüm in Rhineland-Palatinate. With just 32 inhabitants per square kilometre, the 173-square-kilometre test area is very sparsely populated, with more than 12 MW of electricity fed into the grid here from renewable energies (Fig. 1).

Region acquires new grids

In the Eifel region, the installed capacity of renewable energy generating systems in the low to medium voltage range currently exceeds the maximum load by more than 200 % (Fig. 1). This represents a challenge that could occur in many areas of Germany by 2030. Furthermore, the expansion of renewable generation has also not yet been completed in this area. Additional 50 % can be expected by 2030. The demonstration grid encompasses around 110 kilometres of medium-voltage distribution lines with around 100 stations. The following components have been used: data technology, information and communications technology (ICT), a biogas storage system for balancing out electricity peaks, intelligent grid structures with powerful cable sections – effectively electricity highways – and voltage regulators that maintain the voltage in the grid at a constant level (Fig. 2).


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Project management
innogy SE

Operating supplies

Valuation method
Consentec GmbH

Scientific monitoring
TU Dortmund

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