Stochastic Operation of Energy Constrained Microgrids Considering Battery Degradation

TL;DR

This paper introduces a stochastic energy management model for microgrids that accounts for battery degradation, demonstrating improved battery lifespan and the importance of stochastic strategies in reducing scarcity risk.

Contribution

It proposes a linear battery degradation approximation integrated into a stochastic dual dynamic programming model for microgrid energy management.

Findings

Prolongs battery lifetime by over four years with the new strategy.

Stochastic management reduces energy scarcity risk.

Degradation modeling impacts other system resources.

Abstract

Power systems with high penetration of variable renewable generation are vulnerable to periods with low generation. An alternative to retain high dispatchable generation capacity is electric energy storage that enables utilization of surplus power, where the electric energy storage contributes to the security of supply. Such systems can be considered as energy-constrained, and the operation of the electric energy storage must balance operating cost minimization and the risk of scarcity. In this matter, operation dependent storage characteristics such as energy storage degradation are a complicating factor. This paper proposes a linear approximation of battery state-of-charge degradation and implements it in a stochastic dual dynamic programming based energy-management model in combination with cycling degradation. The implications of degradation modelling are studied for a small Norwegian microgrid with variable renewable power generation and limited dispatchable generation capacity as well as battery and hydrogen storage to balance supply and demand. Our results show that the proposed strategy can prolong the expected battery lifetime by more than four years compared to the naive stochastic strategy but may cause increased degradation for other system resources. It is also evident that a stochastic strategy is crucial to retain low risk of scarcity in energy-constrained systems.