PNNL

Abstract

DC electrical distribution systems offer many potential advantages over their AC counterparts. They can facilitate easier integration with distributed energy resources, improve system energy efficiency by eliminating AC/DC converters at end-use devices (e.g., laptop chargers), and reduce installation material, time, and cost. However, DC electrical distribution systems present addi-tional design considerations, largely resulting from potentially greater cable loss magnitude and variation. AC systems are primarily designed according to safety requirements, and the energy efficiently impacts of design considerations are minimized by rules of thumb and experience. Modeling and simulation are rarely used to design such systems. However, the greater depend-ency of DC system energy efficiency on design choices suggests that modeling and simulation may be required. Such system performance analysis is currently not a standard practice, in part due to limited availability and validation of capable software tools. This paper focuses on verifying the accuracy of a Modelica-based Building Electrical Efficiency Analysis Model (BEEAM) toolkit, as a precursor for validating its use to perform system performance analysis and inform design de-cisions. Five lighting systems with varying electrical distribution architectures were designed using market-available equipment, installed in a laboratory environment, modeled using BEEAM, and simulated using three Modelica Integrated Development Environments (IDEs). Simulated and measured results were compared to characterize toolkit accuracy. Initial results revealed that simulated performance was mostly within ±5% of measured performance. While simulation results were not found to be dependent on Modelica IDE, some BEEAM interoperabil-ity issues were identified. In conclusion, the BEEAM toolkit showed promise for the targeted use case, but further work is needed to determine whether the demonstrated 5% accuracy is sufficient for making real-world design decisions.