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For the grid of the future

Like pumped storage systems, battery storage systems are storage devices used to provide a solution to the temporal mismatch between electricity production and consumption. They contain rechargeable accumulators that store electricity in electrochemical form. During charging and/or discharging, chemical reactions take place in the batteries which are crucial to the energy storage process.

As batteries only function with direct current, but the grid uses alternating current, bi-directional inverters are also needed to make AC out of DC and vice-versa. These inverters contain power electronics such as power transistors which convert the current by means of an intelligently clocked on-off switching mode.

Other components of battery storage systems include electrical parts like transformers and switchgear for connection to the grid, air conditioning and ventilation technology for controlling battery temperature and a system control unit (SCADA system and/or control technology) enabling the battery storage system to be operated fully automatically.

A flexible storage solution

Battery storage systems can provide power within a very short time (less than a second to get up to rated power) and for this reason are particularly suitable for applications imposing high demands on the power dynamics, i.e. frequent major changes in power output.

This is why battery storage systems are of particular interest for frequency regulation. However, they do offer other applications that are already being used or are conceivable in the future, for example electricity trading, provision of reactive power to regulate grid voltage or as part of an instantaneous reserve.

In addition, unlike other large storage systems like pumped storage and underground gas storage, battery storage systems are not tied to a particular location and can therefore be planned and built faster.

Hybrid battery storage systems exploit synergies

Basically, various battery technologies can be used to store energy. To exploit the effects of synergies, different battery technologies can be combined to make the most of their respective advantages.

For example, inexpensive high-energy batteries and expensive high-power batteries could be used simultaneously to achieve better cost-effectiveness while offering the same power capacity.

The M5BAT uses five different battery technologies to be able to test and evaluate their respective performance independently of one another and when combined in hybrid operation.

SCADA-System

SCADA = Supervisory Control and Data Acquisition

Reactive power

Alternating current which is not in phase with the voltage

Instantaneous reserve

Very fast attenuation of grid frequency changes