The role of the AC component in human perception of AC–DC hybrid electric fields

Abstract

Electric energy is essential to today’s society. To cope with global higher demand while minimizing land use, efficient high voltage direct current (HVDC) power lines are planned to be mounted on existing alternating current (AC) structures leading to electric fields (EFs) from both AC and DC transmission lines in hybrid configurations. Due to the close proximity to residential areas, the investigation of human hybrid EF perception and underlying mechanisms will be useful to project permitting. To specify the influence of the AC component on the whole-body detection thresholds of hybrid EFs and to explore the lower bound of human hybrid EF perception, 51 participants with an EF detection ability above average were exposed in a double-blind laboratory study. A psychophysical method based on the signal detection theory was used. Very low EF strength combinations, e.g. 1 kV/m AC combined with 1 kV/m DC, were reliably perceived by at least one participant. Detection thresholds were significantly lower with increased AC EF strengths, underlining the key role of the AC component in the human perception of hybrid EFs. Findings will contribute to the assessment of public reaction to the perception of EFs around hybrid overhead power lines and to their optimal designs.

The role of the DC component in human perception of AC–DC hybrid electric fields and a comparison with the AC component

“…The electric force on hairs of superimposed AC/DC EFs was shown to vary with ratio of both field types 13 . In general, hair and skin hydration level influenced EF perception 12 , 14 , whereas others did not find a correlation with skin hydration level 3 , 7 .…”

“…Furthermore, some cases require mounting both AC and DC overhead power lines on the same pylon, leading to hybrid EFs in the immediate vicinity. Compared to single EFs, hybrid EFs produce a more intense human perception, which is highly influenced by the proportion of both field types 1 – 3 , 7 . Even minor changes in this proportion can significantly alter perception 7 and should be taken into account during the design process of high-voltage overhead power lines.…”

“…In a laboratory study, participants showed a detection threshold of 6.76 kV/m DC, while a constant AC EF of 4 kV/m was present 3 . Based on these results, Jankowiak et al 7 investigated in detail how the AC component modulated the detection performance of hybrid EF in 51 highly sensitive participants. Four conditions were generated with a constant AC EF of 1, 2, 3 or 4 kV/m and varying DC EFs between 1 and 16 kV/m.…”

“…Four conditions were generated with a constant AC EF of 1, 2, 3 or 4 kV/m and varying DC EFs between 1 and 16 kV/m. The authors computed total EF detection thresholds per condition by combining AC and DC EF strengths 7 . Detection thresholds of total EF strengths decreased with 8.89 kV/m, 7.82 kV/m, 6.48 kV/m, and 5.7 kV/m in conditions, where 1, 2, 3, and 4 kV/m AC was present, respectively.…”

“…Detection thresholds of total EF strengths decreased with 8.89 kV/m, 7.82 kV/m, 6.48 kV/m, and 5.7 kV/m in conditions, where 1, 2, 3, and 4 kV/m AC was present, respectively. Therefore, a larger proportion of AC EF leads to decreased detection thresholds in hybrid EF 7 .…”