Harmonic analysis of dimmable power leds for street lighting

Power LEDs have several advantages over the widely HPS lamps used in street lighting. Greater energy efficiency, optical characteristics, white light night vision, long life and light control are better, but the possibly higher harmonic emission from these lamps due to the need of switched mode electronic drives has been mentioned as a drawback. These drives cause high disturbances in harmonics. The study presented here is completely based on measurements. The aim of this master thesis is to investigate the emission of harmonics and power quality of LED street light technology and conduct a comparison between LED lamps. For this aim, a power LED lamp has been tested in laboratory then our results has been compaired with a nother investigated LED lamp results. Dimmable electronic ballast has been used to drive a power LED lamp. LED lamp has been tested with different power levels using dimming on a constant voltage power supply and with different supply voltages on full power level as well. Results are somehow similar to other studies showed broadband spectrum of harmonics in the case of power LED lamps and decreasing in harmonic distortions values with increasing harmonic orders.The purpose of this dissertation is to investigate harmonic generation from two different power LED lamp used in public lighting system (PLS). Measurements of LED lamps are carried out during their start-up and normal operation and results are analyzed. A comparative analysis of active and reactive power and current harmonics (in accordance with the IEC 6000-7-4) is performed for high power Light emitting diode lamps. Harmonic distortion has been studied in depth. The first conclusion to be drawn from outcomes is that 3rd, 5th harmonics are dominant. The remained odd harmonics have the same level. Results also indicate a decrease in the harmonic value with increasing harmonic order, and increase in the harmonic value at half load (60%) compared with full load (100%). Power remains nearly constant when decreasing input voltage so it is perceived that harmonic emissions are decreasing due to increase in total current value. Key words: Dimmable function, discharge lamp, electric variables measurement, energy efficiency, harmonic analysis, harmonic distortion, light emitting diodes (LEDs), power quality, street lighting.