title: Evaluation of power flow control strategies for heterogeneous battery energy storage systems
Creators: name: Mühlbauer, Markus
Publisher: name: University of Bayreuth
Year: 2022
Subjects: subject: power flow control strategy
subject: heterogeneous battery energy storage system
subject: methodological framework
subject: evaluation
subject: 620

description: The past decade has seen a rapid transformation of electric power systems in many countries worldwide through integrating renewable energy sources. However, the associated increase in irregular power generation and consumption forces system operators to compensate for resulting power fluctuations. Battery energy storage systems are predestined for integrating renewable energy sources smoothly but demand proper energy management. Research in this area has clearly established that coordinated control is an essential contributor to the reliable operation of energy storage systems and thus the power grid. The development of battery energy storage systems requires operating strategies to efficiently manage the power flow under rapidly and continuously changing power requirements. Therefore, this work aims to identify, quantify, and evaluate the potentials and sensitivities of power flow control strategies for heterogeneous battery energy storage systems in several applications and system designs. Moreover, it aims at developing a versatile power flow control strategy for battery energy storage systems. The experimental research design was used to analyze the causal relationships between the inputs and the outputs of heterogeneous battery energy storage systems. In this context, a methodological framework was developed that includes a validated simulation model of a battery energy storage system and methods to systematically evaluate and visualize these causal relationships for different power flow control strategies and applications. The results showed that the trade-offs between the target indicators “performance,” “efficiency,” and “service life” can be quantified accurately. Furthermore, the individual influences of the power flow control strategies and applications on the target indicators were analyzed. It was shown that, for example, a heterogeneous battery energy storage system could influence the service life of the batteries in different ways depending on the applied power flow control strategy. The findings of this work show that the applied power flow control strategy, system design, and application are essential factors to consider when operating heterogeneous battery energy storage systems. These factors influence the resulting power distribution within the system, which is, in turn, a decisive point for reliable and sustainable operation. In many cases, a trade-off between the target indicators “efficiency” and “service life” was observed, requiring a decision on a more equal or a more individual power-sharing. A more individual power-sharing, for example, might be beneficial in the case of the peak shaving scenario, especially in terms of efficiency. However, this often decreases the service life and demands a premature replacement of a single battery. Generally, this work contributes to the body of knowledge on power flow control strategies for battery energy storage systems by incorporating a methodological framework for researchers and industries to analyze and develop battery energy storage systems. The benefits gained from the methodological framework address system operator needs across a wide range of different applications. This work focuses, among other aspects, on the successful implementation of the methodological framework for heterogeneous battery energy storage systems. However, most battery energy storage systems are included in higher-level systems, resulting in new challenges to be addressed. A further study could assess the potentials and sensitivities of operating strategies for microgrids or other higher-level systems using the methodological framework of this work.