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.
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.
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 = Supervisory Control and Data Acquisition
Alternating current which is not in phase with the voltage