# Rapid Prototyping of Multi-Functional Battery Energy Storage System Applications
## 1 Introduction  
The reduction of greenhouse gas emissions motivates a high penetration of renewable Distributed Energy Resources (DERs). However, this may negatively influence the power quality (i.e., frequency and voltage) and surpass the hosting capacity of the corresponding power distribution grids. Battery Energy Storage Systems (BESS) are becoming an important actor in the power utility grid due to their flexibility and support that they offer. Use Cases (UCs) based on BESS participation are considered in different studies [1; 2], attempting to contribute to voltage and frequency regulation. Other services such as improvement of the hosting capacity and peak-shaving are also possible [3]. Additionally, BESS supports Energy Market Operators (EMO) to benefit from the spot market prices [4] and the end-user to minimize their energy costs [5]. The implementation of the mentioned UCs implies an efficient use of the Information and Communication Technology (ICT) infrastructure and the integration between various stakeholders and DERs. Energy Management Systems (EMS) carry out the integration of BESS UCs. Thus, they require to reach a high degree of flexibility and adaptability. Furthermore, their design becomes quite complex since different power utility equipment and stakeholders are involved. Additionally, due to the offering of many services, a coordination and alignment of control strategies is required. Those issues among others are faced during the development process of EMS. Motivating the conception of a common vocabulary to be approved by different control engineers dedicated to EMS implementation. Existent approaches support control engineers during the engineering process; Systems Modeling Language (SysML) and Smart Grid Architecture Model (SGAM) are highly recommended at the specification stage [6]. Power System Automation Language (PSAL), a Domain Specific Language (DSL) for power systems, automates the design and implementation of smart grid applications [7]. Besides this, a power utility automation standard called IEC 61850 models DERs functionalities [8]. The implementation of them is driven by automation standards such as IEC 61499 [9] and IEC 61131-3 [10]. On this basis, this paper analyzes current smart grid and automation approaches and points out the lack of an integrated framework and methodology that guides control engineers during the design and implementation phase of EMS applications. As a solution, this paper proposes EMSOnto, a framework focused on interoperability, flexibility, complexity, and overlapping issues raised during BESS UCs implementation. Current efforts to handle those issues are evaluated, hence a set of four requirements are identified which provides the basis for the EMSOnto conception. The core part of the EMSOnto approach is an ontology (i.e., EMS-ontology) that models different aspects of a multi-functional BESS such as potential conflicts between UCs, variables exchanged across the EMS communication architecture, structure of control strategies, etc. This modeling process is aligned with domain-specific approaches like IEC 61850 and SGAM. PSAL proposes a data model for power systems also based on SGAM and IEC 61850, but concepts for the abstraction of BESS services were not tackled. A main benefit of ontologies is to infer new knowledge from explicit knowledge. This benefit is key in the identification of conflicts, a feature supported by EMSOnto and not contemplated by any of the previous mentioned approaches. In addition to this, a friendly method to gather information from control engineers based on spreadsheet templates (i.e., EMS-templates) is exposed. This mechanism enables the population of the EMS-ontology. IntelliGrid enables the gathering of data by UC templates, however they are not suitable for collection of static and dynamic variables presented in an EMS. On the other hand, Model-Driven Engineering (MDE) is employed to semi-automatically generate software artifacts to be deployed in power system and automation tools.