Qualitative Assessment of Dynamic Multi-Use Energy Management and String Management Techniques for Large-Scale Battery Energy Storage Systems

Inhalt:
Due to their capability of energy time shifting and fast provision of power, large-scale battery energy storage systems (BESS) are suited for diverse applications such as frequency containment reserve, automatic frequency restoration reserve, day-ahead trading and intraday continuous trading. Splitting the control tasks into an energy management dynamically allocating resources to these applications and a string management controlling the internal power split, this paper presents challenges in both control levels and potential solutions. The first group of challenges are related to internal characteristics of BESS, such as nonlinear losses and aging, as well as a potential heterogeneity in size, state of health or technology of the strings making up the system. Furthermore, application characteristics such as typical power profiles, price uncertainty, cross correlation among the market prices, simultaneous decisions, price elasticity and weighing up potential profits from one application against the resulting constraints on the others are considered. After analyzing these system and application characteristics, this paper assesses well-known optimization techniques for the energy management with respect to their assumptions and simplifications, highlighting drawbacks and risks and how less commonly used extensions to these techniques can tackle them in the context of specific multi-use combinations. In a similar way, string management strategies are discussed with respect to their assumptions and simplifications in order to identify their optimal use cases and limits. The paper thereby highlights important issues to consider in the implementation of a multiuse BESS in the real world and serve as a reference point for future research.