Long-term degradation based analysis for lithium-ion batteries in off-grid wind-battery renewable energy systems

This work presents a mathematical framework for calculating Li-ion batteries useful life by coupling electrochemical and thermal aging models. The model takes into account the impact of operating conditions of real wind-battery power stations including charge/discharge profiles and control strategies to predict battery degradation over time. The model estimates battery end of discharge capacity with a RRSME of 1.1% in comparison with experimental data. In addition, the maximum relative error to predict battery voltage in the plateau region of charge/discharge curves is 1.3%. Results show a remarkable impact of operating conditions on battery bank lifetime. Analyzing different case studies predicts a wide range of 4.6-11.6 years for battery longevity. Moreover, the model shows that controlling the maximum allowed battery state of charge set point improves battery bank lifetime up to 63%. Hence, the proposed model is a powerful decision support tool to evaluate the impact of off-grid wind-battery systems operating conditions on the battery lifetime. (C) 2018 Elsevier Ltd. All rights reserved.