A Digital Instrument for Light Flicker Effect Evaluation

The voltage waveform in an electric power system usually presents a fluctuation due to the intermittent operation of nonlinear devices. In some cases, the frequency and width of these voltage variations can produce a physiologically irritating phenomenon due to luminance fluctuations of the lighting (flicker effect). In addition to the visual inconvenience, some of the electrical equipment can be strongly disturbed. The International Electrotechnical Commission standardized the implementation of a flickermeter based on the simulation of the process of physiological visual perception to supply information about the human reaction to voltage amplitude modulation. A standard parameter (i.e., the flicker severity index P_st) is obtained from the cumulated probability function of the instantaneous perception. In this paper, a different measurement approach for the flicker effect evaluation is proposed. It is based on the calculation of the luminous variation perception function by processing digital samples of the acquired voltage. The choice of this technique is motivated by the aim of simplifying the flickermeter implementation and reducing the hardware requirements. A prototype of the instrument has been implemented, and the performance has been evaluated, by means of direct comparison with standard flickermeters. In this paper, the main results are also reported.