Power Quality Survey of Voltage Stabilizers and Uninterruptible Power Supply With Nonlinear Loads

Amongst the power quality problems faced in Nigeria, interruption and voltage fluctuation seem to be foremost. Thus, household electrical and electronic appliances are most times under the threat of outages and low voltage supply which cause them to malfunction or in extreme cases, get damaged. To address these problems, the use of uninterruptible power supply (UPS) and automatic voltage regulator commonly refer to as “stabilizer” has become very popular. The objective of this work is to examine the quality of these devices when powering other nonlinear devices. The experimental study was carried out by using a power harmonic analyzer to display the output parameters and waveform from each device under test when powering nonlinear loads. Parameters measured for each device were voltage, current, frequency, peak-to-peak voltage, total harmonic distortion (THD) and crest factor. The results showed that for the measured parameters, while other parameters relatively remain within the standards, the THD took an exemption as it was relatively higher with a range of 9.9 to 19.9 % for various combination of loads. Though the outputs from the UPS were relatively higher than that of stabilizer (except for THD and crest factor where those of the stabilizer were higher), there was no significant difference between the parameter values measured. The implication of this was that increasing utilization of UPS and stabilizer will invariably continue to contribute more to the pollution of the existing weak network. Adequate measures were suggested to mitigate this. This research can be useful for the stakeholders in power industry for power quality improvement.