Power quality performance of energy-efficient low-wattage LED lamps

Light-emitting Diode (LED) lamps are more versatile and energy efficient compared with conventional light sources. This paper investigates two main problems related to power quality, namely, the harmonic generation from LED lamps and the effect of voltage sags on LED lamps. Laboratory tests on various LED lamps are conducted and the electrical characteristics of LED lamps are tapped under different conditions. Frequency domain analysis is then performed to investigate the generated harmonics. Then, voltage sag sensitivity analysis is performed by obtaining signals from a photo sensor, the different parts of a lamp ballast, and input voltage. The analysis includes the effects of varying sag depth and voltage sag duration. The findings are compared with the SEMI F47 standard curve, which predicts the effects of voltage sags on lamp performance. Experimental results show that the LED lamps produce a considerable amount of current harmonics. Moreover, different types of LED lamps were found to produce different levels of current harmonic depending on the ballast configuration. This harmonic distortion can be reduced by combining various types of LED lamps. Voltage sag tests show that all the tested lamps are sensitive to sag depth and sag duration. (C) 2013 Elsevier Ltd. All rights reserved.