Reliability Framework Integrating Grid Scale BESS Considering BESS Degradation

To ensure the future networks’ secure and flexible operation, NOs will increasingly rely upon grid-scale storage services as a secondary (ancillary) service. During critical contingencies, NOs may drive some battery energy storage systems (BESS) that operate at higher depth-of-discharge cycles for increasing reliability benefits. This eventually could lead to accelerated degradation of BESS. The reliability benefits versus the accelerated BESS degradation risks over the BESS lifetime are not deeply investigated in the up-to-date literature. This paper develops a reliability evaluation framework integrating a Bi-Level Sequential Monte Carlo loops with a detailed BESS degradation model. The integration captures the BESS normal and accelerated cycle and capacity degradation across a multi-year network analysis. Annualized indices are defined for assessing the risks of BESS accelerated degradation named as expected equivalent life cycle accelerated degradation (EELCAD), expected equivalent capacity degradation (EECD) and expected battery accelerated degradation costs (EBADC). In addition, it provides a techno-economic assessment of reliability benefits versus the degradation risks over the battery’s lifetime. Therefore, the paper presents an in-depth analysis of the benefits and risks associated with battery degradation and the potential implications in long-term planning studies.