Analysis of Harmonic order levels at Power Lines to Improve the Power Quality

Abstract

This work aims at analysis and establishing harmonic levels at various points of KPLC power lines. It involved collection of harmonic order levels from generation, distribution and point of common coupling (PCC). The data were collected using Zera portable reference equipment which provided an instantaneous values and power quality analyzer (PQA) which logged data at specified time interval. Different power stations, substations and large power consumers were visited and data collected. The analysis has ascertained that large power consumers supplied on low voltage (415V) have their harmonics current levels far beyond the threshold limit as defined by the IEEE 519-1992, as compared with the power consumers supplied with medium (11,000V) and high voltage (above 66,000V. In addition, voltage distortions on transmission lines were noted to be more severe vis-a –vis the current distortions. The reasons for these are presumed to be because low voltage consumers feed the harmonics direct to the power line as opposed to the medium and high voltage consumers where most of the harmonics are filtered out at step down transformers at the consumer’s premises. On the other hand, high voltage distortions on transmission lines can be as result of high line voltage hence voltage harmonics tends to be higher than the current. The power utility needs to define the admissible harmonic levels to be met by the large power consumers supplied on low voltage to reduce the adverse effects of high harmonic levels in the power electrical distribution.