Techno-Economic Analysis and Optimal Control of Battery Storage for Frequency Control Services, Applied to the German Market

TL;DR

This paper presents a comprehensive data-driven framework for optimizing battery storage investment, sizing, and control for frequency regulation, considering degradation, costs, and regulatory compliance, applied to the German market.

Contribution

It introduces a holistic, stochastic optimization approach that accounts for battery degradation and regulatory constraints, improving upon prior methods by reducing data needs and execution time.

Findings

Optimal battery size is 1.6 MW, 1.6 MWh for maximum NPV.

Calendar aging significantly impacts battery degradation.

Profitability depends on costs and future frequency control prices.

Abstract

Optimal investment in battery energy storage systems, taking into account degradation, sizing and control, is crucial for the deployment of battery storage, of which providing frequency control is one of the major applications. In this paper, we present a holistic, data-driven framework to determine the optimal investment, size and controller of a battery storage system providing frequency control. We optimised the controller towards minimum degradation and electricity costs over its lifetime, while ensuring the delivery of frequency control services compliant with regulatory requirements. We adopted a detailed battery model, considering the dynamics and degradation when exposed to actual frequency data. Further, we used a stochastic optimisation objective while constraining the probability on unavailability to deliver the frequency control service. Through a thorough analysis, we were able to decrease the amount of data needed and thereby decrease the execution time while keeping the approximation error within limits. Using the proposed framework, we performed a techno-economic analysis of a battery providing 1 MW capacity in the German primary frequency control market. Results showed that a battery rated at 1.6 MW, 1.6 MWh has the highest net present value, yet this configuration is only profitable if costs are low enough or in case future frequency control prices do not decline too much. It transpires that calendar ageing drives battery degradation, whereas cycle ageing has less impact.