Abstract
The penetration of harmonics in residential power system networks due to the widespread use of nonlinear loads such as Personal Computers (PCs) can cause severe problems including voltage and current distortion. Almost all residential customers are subjected to variations in the system voltage and frequency. Also, the source impedance is different for different customers depending on their distance from the utility transformers and distribution cabinets and the system loading. Hence, the purpose of this paper is to investigate the effects of the voltage amplitude, source impedance and system frequency on the harmonics produced by a single PC for variations within practical limits. Experimental measurements and computer simulations are performed to confirm the observations.
1 Introduction
Recently, residential customer¶s input voltages are becoming more distorted due to the widespread use of nonlinear loads such as Personal Computers (PCs). It has been estimated that by 2012, 60% of the loads on power system in USA will be nonlinear loads [1]. The penetration of harmonics in residential power system networks can cause severe problems such as decrease in power factor, increase in voltage distortion, increased interference with communications networks, impact energy metering, increase system losses and decrease the overall system efficiency [2-7].
5 Conclusion
In conclusion, source voltage fluctuation causes THDi, individual harmonics, power factor, active and nonactive power to be changed. Increasing the source voltage increases THDi, active, nonactive and apparent power and the power factor decreases. Practical measurement shows that although most of the individual harmonic current increase with increasing source voltage, some harmonics might decrease. Furthermore, all measurements and simulations show that current distortion variations for a residential customer are negligible for source impedance and system frequency change within prescribed limits. However, current distortion slightly decreases as source impedance and system frequency increase.
