Using DC uninterruptible power supply (DC UPS) systems from telecommunications to provide balancing energy for electricity grids

摘要

The implementation of the energy revolution (Energiewende) requires greater use of renewable energy sources. As a consequence the power generation systems need to be adapted to cope with fluctuations in energy input. To handle these fluctuations a greater need for balancing- and back-up energy is expected. This paper describes an innovative method to provide balancing energy from DC UPS Systems used in the telecommunication industry. Modernized telecommunication technology which operates more energy efficient could unlock some of the back-up capacity available in Deutsche Telekom's existing DC UPS systems used in its network nodes. DC UPS systems usually only have one rectifier, which means they cannot convert a DC signal back into an AC signal and feed the current back into the power grid. Using these systems for the provision of balancing energy requires the following modified mode of operation: Where there is a negative reserve (excess electricity), the network nodes are supplied with electricity from the grid and batteries are charged at the same time. Where positive reserve is required (electricity shortage), network nodes are supplied with electricity from the battery, thus reducing the load on the energy grid. The liberalised energy market offers some options to use the provision of balancing energy for business activities. Primary energy reserve has been identified as best option to market the provision of balancing energy from UPS systems. Consequently the technical changes of the original UPS System made in two pilot projects in Hamburg are described. The pilots will go online in autumn 2013 run for a duration of two years.