Profitability of different li-ion batteries as back-up power in LVDC distribution network

Abstract

This paper studies the profitability of different lithium-ion batteries as back-up power in low voltage direct current (LVDC) network. Battery energy storage can prevent part of interruptions in LVDC network that happen due to failures in medium voltage (MV) network. In the present Finnish regulation model avoiding customer interruptions directly affects distribution network operator's profits by decreasing quality of supply deductions that are used in reasonable return calculations. LVDC technology provides a cost-efficient alternative for replacing low-loaded MV branches of the electricity distribution network. Benefits of LVDC are large power transfer capacity with low voltage, cost saving potential and improvements to reliability and voltage quality [1]. Elenia Oy has had pilot implementations already many years with promising results [2]. The key finding of the paper is that using battery energy storages to avoid customer interruption cost can be financially feasible in many medium voltage branches when the interruption frequency per branch is taken into account and the battery size is optimised based on the power requirement of the branch.