Integrating the market into the smart grid
In the German electricity grid, which has evolved organically over time, the power flow in the medium and low voltage grids used to be typically characterised by centralised energy distribution, i.e. via central feed-in via local substations and the ordered power consumption by the connected loads. The power flows from multiple decentralised suppliers, which have resulted from Germany's Energiewende – its energy transition, were never originally envisaged when designing the grid so that the changed load situations are now stretching the existing networks to the limits of their absorption capacity.
In principle, two approaches are available for solving this problem: the issues that occur can be reduced by expanding the grid capacity, i.e. by replacing transformers with transformers with higher performance classes, and by upgrading the transmission grid. However, this usually incurs considerable costs. In addition, it needs to be taken into account that the described overload situations are limited to a few hours per year. For optimum and safe operation of the medium and low voltage grids, it therefore makes more sense to equip the networks with automation technology and thus expand them to form smart grids.
Ancillary services at the distribution grid level
In addition to these challenges, distribution grids will have to fulfil further (market-driven) requirements in the future. During the course of the energy transition, the provision of ancillary services – i.e. the provision of measures to ensure grid stability – will also need to be adapted to the changing structures. While ancillary services are currently exclusively coordinated at the transport network level and are primarily provided by large-scale power plants, the decentralised nature of the future generation structure means that there is a considerable need to largely provide these services at the distribution grid level as well. In order to provide a correspondingly large, flexible output, several decentralised generators and loads will need to be combined to form a virtual power plant and operated in a coordinated manner, which in turn will create additional, new kinds of loads in the medium and low voltage grids. In addition, the steadily increasing proportion of directly marketed electricity from decentralised generation plants will also impact on the grid utilisation. In recent times, the professional world has therefore been increasingly focussing on the interaction of smart grids with so-called smart markets. In particular, the operators of distribution grids are increasingly interested in utilising the flexibility of generation and load systems in a network-serving manner.
Reducing the cost of the energy transition
The overall objective of the joint project is to conceive, implement and validate a holistic concept for integrating smart market participants in smart grid systems. In doing so, the market should be able to act as freely as possible, whereby the automation system should only have to intervene in the market in critical grid situations. This should enable the flexibilities in the electrical distribution grid to be optimally used and thus reduce the overall costs of the energy transition. The functionality of the developed system will then be validated in a field trial in a real low voltage network.
The project is still in its initial stages. After the conceptual phase has been completed by mid-2017, a coordinating control concept will be developed by the beginning of 2018 and implemented in the hardware components for the entire system by the end of 2018. The field trial will start at the beginning of 2019 and continue until the end of the project.
The project members consist of the University of Wuppertal (BUW), ENTEGA AG and the Fraunhofer Institute for Wind Energy and Energy Systems Engineering (IWES). ARGE Netz GmbH & Co. KG and Städtische Werke AG will also be providing their virtual power plants for the field trial as associated partners. The University of Wuppertal is responsible as consortium leader for the project organisation, conception and system merging. Fraunhofer IWES is responsible for designing the control algorithm and integrating it into the control software for the virtual power plants. ENTEGA will be applying its experience in developing cellular systems and operating a virtual power plant control system to the test operation and will conduct the field trial together with the partners in their network areas.
09/2016 – 08/2019
Bergische Universität Wuppertal