Mapping and assessment of harmonic voltage levels for railway traction supply stations in Sweden

• Mapping and evaluation of harmonic voltage levels in the Swedish railway power supply for several traction converter stations. • Assessment of time-varying behaviour, frequency converter technology signatures, and impact of railway traffic. • Deployment of a framework for evaluating harmonic distortion considering the particularities of public grid connection (50 Hz) and railway grid side (16 ⅔ Hz). • Extensive visualization and assessment using traditional methods for long-term measurements as statistical values for different time scales and representations, comparison with standards when it is suitable, and trend analysis. • Proposed a methodology and findings that can be reproduced for other electrified transportation systems with similar characteristics as electrical road systems, electric vehicle charging infrastructure, etc. Assessing harmonic distortion measurements in the electric railway power systems (ERPS) requires evaluating the time-varying behavior, interactions, and performance in different time scales. This paper aims to map and assess harmonic voltage levels in 13 traction converter stations for the Swedish railway power supply system, with findings that have direct practical implications. For that, measurements from the public and railway grid sides for 69 weeks are analyzed. Statistical values are explored for the harmonic voltage spectra and total harmonic distortion (THD) variation. The public grid side measurements are investigated using 95th percentile weekly values, and performance is evaluated by comparing the recommended planning levels of IEC 61,000–3–6. The intraweek variation complements the information about the time-varying behavior of the THD. The 95th percentile, minimum daily values, and intraday variation are explored to understand the time-based behavior since there are no reference limits from standards for comparison, looking to the railway grid side. Extended analysis is placed on the railway grid side to highlight some aspects of measurement time-aggregation based on 10-min values, and time-series trend analysis is used to confirm traffic planning impact. Discussion and findings regarding railway operation, the technology deployed at the traction converter station, time-varying behavior, traffic planning impact, measurement time-aggregation, and spectra patterns were presented.