Evaluation of a Li-Titanate battery module in frequency regulation ancillary service conditions

Power grids are deeply changing in recent years due to the rapid deployment of renewable energies and a growing worldwide energy demand. Energy storage systems are promising technologies to provide electric networks with ancillary services. Currently, few data referred to batteries operation in power network ancillary services utilization are available. This could limit the evaluation of battery technologies in relation to those applications. Li-Titanate technology is characterized by a high specific power and it guarantees high safety in stressful conditions. In this context, the performance of a Li-Titanate Toshiba® battery, subjected to a frequency regulation cycle, was studied by CNR-ITAE. In the meantime, the manufacturer (Toshiba) tested the battery module in CC (Constant Current) charge/discharge cycles. This paper reports the results coming from the testing campaign at CNR-ITAE throughout 250 test days. A comparison between battery degradation obtained during frequency regulation and constant current tests was analyzed. Battery performance indicators (such as SOH, capacity and efficiency reduction) were evaluated. Finally, in order to optimize the size of energy storage systems based on lithium titanate technology operating under primary frequency regulation conditions, an evaluation tool was implemented.