A proposal for UIE/IEC flicker measurement using digital filters: equipment prototype and validation

This work aims at proposing a methodology to appropriate an existing digital instrument for power quality measurement, namely STDAQEE (power quality diagnostic and analysis system), so as to obtain voltage flicker monitoring capability in accordance with the UIE/IEC standards. Digital filtering technique in time domain is used, which is properly established on digital signal processing and control theories. IEC tabulated voltage fluctuation signals and also a random voltage fluctuation are used to test and validate the prototype. In this last case, flickermeter response from experimental laboratory facility and from a computational model (MatLab program) are compared. The results are good enough to support the methodology and provide useful information to improve the proposed equipment.

I. Introduction

Many phenomena in voltage and/or current signals in deviation of ideal conditions can be denoted as an Electrical Power Quality problem. Among them, voltage fluctuation is pointed out as an important matter because it has an intermittent and/or steady state behavior, and can propagate throughout the electric system, reaching many consumers. This phenomenon can be defined as voltage magnitude variations in RMS or peak value, in the range of 0.9 to 1.1 pu and frequencies up to 35 Hz [1]. It may be caused by variable demanding loads, such as electric are furnaces, welders, rolling mills, large fluctuating motor loads, etc.