Voltage Fluctuation Test for LED Lighting -Assessment of Relations between ΔV10 Flicker Index and Illuminance Change-

To evaluate this phenomenon, we combined subjective visual assessments with a numerical analysis of illuminance waveforms. The subjective evaluation involved human observers who assessed the visibility of flickering under controlled conditions, while the numerical analysis quantified the magnitude of illuminance fluctuations based on waveform data. By combining these two approaches, the study enables an understanding of flicker behavior from both perceptual and physical perspectives.

We focused primarily on light emitting diode (LED) lighting, which has become the dominant lighting technology in Japan due to its high energy efficiency and long operational lifespan.

The voltage fluctuations of LED fixtures may vary depending on their design and control circuitry. We also analyzed incandescent bulbs for comparison because they have traditionally served as a reference in studies on flickering in light fixtures. In Japan, voltage fluctuations are regulated using the ⊿V10 index to suppress flicker. This index represents the cumulative effect of voltage fluctuations over time. Voltage fluctuations caused by the control function employed in PV systems to prevent unintended islanding result in exceedance of the ⊿V10 threshold. We investigated how ⊿V10 correlates with flicker occurrence in LED fixtures and examined whether factors such as manufacturing, physical shape, and rated power influence flicker sensitivity.

The results are summarized as follows.

(1) Subjective Evaluation

LED fixtures generally exhibit equal or greater resistance to voltage flicker compared to incandescent bulbs. However, some LED fixtures are more prone to flickering, which indicates that there must be some variability in their designs. No consistent correlation was found between flicker sensitivity and different manufacturers, shapes, or power ratings.

(2) Numerical Analysis

The measured illuminance fluctuations were analyzed in the frequency domain.

A positive correlation was observed between the ⊿V10 index and the amplitude of illuminance fluctuation. Fixtures that exhibited flickering demonstrated higher sensitivity, as indicated by steeper slopes in the correlation.

(3) Cross-Validation

The subjective and numerical results were consistent, which confirms the reliability of the evaluation methods.

Many LED fixtures began to exhibit noticeable flickering when ⊿ V10 exceeded 3. In conclusion, we investigated the ways that voltage flicker affects modern lighting systems in

Japan, and our findings suggest that while LED lighting generally offers superior flicker resistance compared to incandescent bulbs, performance varies among individual fixtures.