The electric power system is transforming from a strict hierarchy into a distributed scheme that consists of prosumers and other service providers. Some services require interactions more complex than request-response. To reach functional interoperability, such services necessitate an agreement about what actions happen, in which order, and in which conditions. Such agreements can be modeled as service choreographies, a concept familiar from microservice architectures (MSA). However, the management of choreographies is demanding, especially in inter-organizational (or actor-to-actor) schemes, if changes occur frequently or the number of participants and choreography instances is high. This article proposes Discografia, a framework to support the distributed execution of service choreographies modeled with the standard Business Process Model and Notation 2.0 (BPMN2). Beyond distributed execution, certain operations must be centralized, specifically for security as well as lifecycle and execution support. The framework is proven with a software prototype to demonstrate applicability. The prototype coordinates the charging of electric vehicles (EV) among competing aggregators operating in urban charging hubs (UCH). Additionally, the concept is evaluated with theoretical calculations that suggest reduced manual effort in communicating choreography specifications. Thus, this paper argues that Discografia concept for distributed service choreographing facilitates inter-organizational interoperability, an essential factor in future power system.
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