Development and use of Renewable Energy Sources is one of the key elements in European Electricity Research. However connecting energy sources such as photovoltaics and wind turbines to the electricity grid causes significant effects on these networks. Bottlenecks are stability, security, peaks in supply & demand and overall management of the grid. Energy storage systems provide means to overcome technical and economic hurdles for large-scale introduction of distributed sustainable energy sources.
The GROW-DERS project (Grid Reliability and Operability with Distributed Generation using Flexible Storage) investigates the implementation of (transportable) distributed storage systems in the networks. The project is funded by the European Commission (FP6) and the consortium partners are KEMA, Liander, Iberdrola, MVV, EAC, SAFT, EXENDIS, CEA-INES and IPE.
This paper describes the results of the first phase of this innovative demonstration project. Within the framework of this project several storage systems have been realised. These systems consist of a storage medium (a Lithium-ion battery or a flywheel), an inverter, an overall energy management system and a connection to the local distribution network. Both the Lithium-ion based systems and the flywheel based system have first shown to be compliant with normal grid operation during laboratory tests. Subsequently field demonstrations have been done with both storage systems. In general these field tests showed that all systems worked appropriate. With the experience of the first three field tests a new field test will be realized to combine the three storage systems at one location.
In parallel a technical-economic assessment tool is being developed in the GROW-DERS project for optimal distribution network management. The tool uses input parameters related to the grid, the storage system, the electricity demand and supply, electricity prices and weather forecasts. Taking user-defined ranking criteria into account the assessment tool provides specifications for the most suitable storage system in terms of type of storage system, number of systems, location, etc. In the first phase of the project the tool has demonstrated that grid-connected storage systems can be applied to keep the grid within technical constraints. The economical feasiliby strongly depends on local conditions and is expected to become positive in the near future. In the next phase the tool will be optimized and validated with results of the field tests.
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