By Edrisi Munoz, James Allan, Hanmin Cai, and Heer Philipp | Urban Energy Systems Laboratory, Empa.

In this article the Urban Energy Systems Lab (UESL) at Empa describes how the research team is using ontologies to organise the data requirements for our digital twin. The UESL team at EMPA supports the digital twin development work package in REFORMERS, leading the task: “Energy data space – past, present, and future” and contributes to developing and calibrating models used by the REFORMERS digital twin.

Energy Flexibility

The traditional approach distribution system operators (DSOs) use to manage congestion involves reinforcing the grid, which demands substantial infrastructure investments. An alternative solution relies on Energy Flexibility to leverage local supply- and demand-side flexibility to delay or avoid grid reinforcement, thereby reducing the required investments. Energy flexibility can be described using the concept of a flexibility envelope, as shown in Figure 1. The upper and lower energy bounds represent extreme scenarios, indicating the range of flexible power and the corresponding duration available for flexibility. Recent studies suggest that utilizing demand-side flexibility presents significant economic opportunities to facilitate the transition toward a sustainable future.

Figure 1. Copyright: REFORMERS 2024 – Author: Hanmin Cai.

The models being considered for the REFORMERS Digital Twin include: an electricity grid model, multi-energy flow model, building model, and heat network. Developing a data framework requires understanding these models to support their functionality when deployed on the twin. At UESL, we are developing this data framework to support these models by handling time and spatial input data and results. This includes: historical performance data, real-time operational data, and future forecasts, such as price changes and energy availability. 

Ontology and architecture

The REFORMERS data space will also incorporate an ontology to describe entities formally. An ontology goes beyond a vocabulary by not only defining concepts but also defining the relationships to facilitate information sharing in a domain. For example, in the case of the flexibility model, the ontology must define the input entities, including ambient temperature, solar irradiance, thermal power demand, and indoor temperature; and also the model outputs, including, the time series of energy flexibility, the time series of power flexibility, and state of charge. The three layers of the REFORMERS digital twin architecture: data, models, and services are shown in Figure 2. 

Figure 2. Data management framework DT, Copyright: REFORMERS 2024 – Author: Edrisi Munoz.

Future work will investigate how data spaces, which are focused on providing accessibility, integrity, and security, can be combined with CityGML datasets to support forecasting, energy analysis, scenario governance, and energy management. Check our research track to find out more

Visit the project website at www.reformers-energyvalleys.eu and follow their social media page on LinkedIn for latest updates, or get in contact at info@reformers-energyvalleys.eu