Academic journal article American Academic & Scholarly Research Journal

Impact of Personal Computers and Compact Fluorescent Lamps on the Power Quality

Academic journal article American Academic & Scholarly Research Journal

Impact of Personal Computers and Compact Fluorescent Lamps on the Power Quality

Article excerpt

Abstract. The use of non-linear loads continues to expand in both industrial and commercial applications resulting in increased harmonic current distortions on the electrical system. This paper presents the simulation modeling of a personal computer (PC) and a compact fluorescent lamp (CFL), by using ATPDraw, as non-linear loads, which are continually using for both domestic and industrial applications and which can be considered as a source of harmonics and that results in power quality deterioration. The interest in this paper is focused on estimating the harmonics, that may exist in the current waveform when the PCs and CFLs are connected to the power supply and on estimating the excessive losses in low voltage line, where the results presented show that the use of these kinds of loads increased the level of excessive losses.

Keywords: PC, CFL, non-linear load, harmonics, excessive losses, power quality.

(ProQuest: ... denotes formulae omitted.)


Recently the interest has been growing to deal with the problems related to the subject of electromagnetic compatibility (EMC), which studies the interference between the different electrical appliances and their negative effects on the power quality. Negative reverse effects in general is called electromagnetic disturbance. Definitions of electromagnetic disturbance types may differ from author to author, specially between electronics and electrical engineers, but in common they are (James, 1994) outages (interruptions), surges (lightning or switching surges), undervoltage (voltage drop), harmonics, voltage sags, voltage swell and overvoltage. Harmonics has received special attention as one of the largest sources of electromagnetic disturbance as they generate voltages with frequencies different from the network frequency or absorbs currents with a non-sinusoidal waveform.

Among of the sources of harmonics there are PCs, CFLs, copiers, fax machines, TV sets, and any equipment that contains a switch mode power supply that uses the neutral of a thirdphase, four-wire power system for its connection. The harmonic currents may lead to overheated wiring and panel boards, false tripping of protective devices (such as circuit breakers), humming of transformers and motors. In steady running conditions the electrical appliance does not always behaves as a non-linear load, but in switching-on phase, because of the inrush starting current, it always makes negative effects to the supply network and also to the other electrical appliances connected to the point of common coupling (PCC).

This paper presents the implications for distribution networks for widespread use of PCs and CFLs in terms of losses and power quality. In order to quantify the effects of the use of PCs and CFLs simulation models of PCs and CFLs are applied by using ATPDraw (H. K. Høidalen, 2012).


The calculation of losses in power systems under purely sinusoidal conditions is straightforward because it is based in conventional power flow that assume linear impedances throughout the system. The increasing waveform distortion in power systems due to the widespread use of nonlinear loads requires losses to be calculated using more suitable techniques. Here it is important to remember that harmonic currents increase the rms or total effective load current. The rms current considering the harmonics is given by (Francisco, 2006) (Walter, 1995) as follows:

... (1)

Where Ih,rms is the current at any harmonic order (h). I1,rms refers to the fundamental harmonic.

The total harmonic distortion (THD) which is the harmonic index is given by (IEEE definition) (Francisco, 2006) as:

... (2)

and the relationship between the rms current and the total harmonic distortion of the current is:

... (3)

This small increase in current above the rms current will produce increased losses, ¢P, relative to the case in which current contained no harmonics. …

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