Introduction & Background

The expansion of photovoltaic systems and electric vehicle charging stations is accelerating rapidly. Austria added over 2 GWp of PV capacity in 2023, while EV charging points increased by nearly 50% in just one year. But this growth in power electronics brings an emerging challenge: direct current (DC) emissions in AC distribution grids are becoming an increasing problem.

DC emissions currently lack comprehensive international standards. Yet their impact on transformers, cables, and grid infrastructure is significant. The core challenge is that precise measurement of these emissions is extremely difficult and requires high-precision measurement technology.

Standard AC/DC converters cannot capture the emissions accurately enough—and therefore cannot correct them either. At NEO Messtechnik, we’ve developed the specialized instrumentation needed for this challenge. Our research collaboration with the University of Applied Sciences Technikum Vienna uses high-precision fluxgate transducers and our PQA8000H power quality analyzer to finally make these invisible emissions visible and measurable.

Abstract of this IEEE Paper

The expansion of distributed renewable energy technologies like photovoltaic systems and electric vehicle (EV) charging stations and its active power electronics causes direct current (DC) emissions in the electrical AC distribution grids which are currently not monitored. Although emissions in the harmonic frequency range (50 Hz to 2 kHz) are well standardized, for DC emissions no standards are defined yet. However, failure to detect and standardize DC emissions do have a significant negative impact on the public grid through grid disturbances or quality losses. Measurement and protection systems are affected as well as thermal effects on cables or transformers are given. In this study the DC current emissions of EV charging stations and PV systems are analyzed and characterized at the reconstructed electrical distribution grid of the university of applied sciences Technikum Vienna. The results show that the DC current emissions depend on the design of the active power used in V2G chargers and photovoltaic systems and how they vary at different power levels (low power vs. high power). The research indicates that the emissions can reach up to 200 mA from a single EV charger.

Read the complete IEEE paper for detailed methodology, measurement results, and technical analysis:

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