Field tests experience from 1.6MW/400kWh Li-ion battery energy storage system providing primary frequency regulation service

Lithium-ion battery energy storage systems (BESSs) represent suitable alternatives to conventional generating units for providing primary frequency regulation on the Danish market. This paper presents aspects concerning the operation of the BESSs in the Danish energy market while providing upwards primary frequency regulation. Moreover, the paper presents the experience form field tests dedicated to the evaluation of the BESSs' performance degradation. For this purpose, capacity measurements, Hybrid Pulse Power Characterization (HPPC) measurements, and AC impedance measurements were performed on the BESS demonstrator located in Western Denmark and initial results are introduced and discussed. These measurements can be used to validate models for battery ageing during realistic operation or to develop the diagnostic tools for the BESS.