DIGITAL MEASUREMENT OF VOLTAGE FLICKER

Quality of power is of prime concern to power companies. This paper deals with cyclic variations in the envelope of voltage waveforms. The European power utilities have done a substantial work already in its characterization, based on the effects on visual perception. They have also established a norm for the calculation of an instantaneous flicker level, a short-term severity coefficient, and a long-term severity coefficient. The measurement techniques, that they propose, are basically designed for analog instrumentation. It can be readily seen that digital implementations of the analog design are neither cost effective nor optimal in performance. This paper proposes a method for direct calculation of flicker level from digital measurements of voltage waveforms. Results based on simulated data indicate that the proposed approach yields sufficiently accurate results for 1024 point FFT with 480 Hz. sampling using a 12 bit A/D. Thus a value of instantaneous flicker level can be obtained every 2.13 seconds.