Abstract
Although the number of pieces of equipment that emit harmonic currents has increased, the harmonic voltages in Japan have gradually decreased since about 1999. In addition, the harmonic voltages are generally lower during the daytime when there is greater usage of different types of equipment that emit harmonic currents. In a previous study, the authors showed that the reason for this phenomenon is that the phase angles of the harmonic currents emitted by three-phase equipment of consumers using 6.6kV or higher voltage power supply and the phase angles of harmonic currents emitted by other equipment are almost opposite, and they cancel each other out. In this paper, we classify equipment into six groups depending on the number of phases (i.e., single-phase or three-phase) and users' supply voltage. And the ratio of the contribution of each group to the fifth harmonic voltage is then quantitatively clarified. Time trends of the fifth harmonic current per kW and the effective power of each group are assumed by using measured data. The ratio of each group is assumed by making the time trends of the composite fifth harmonic current of all groups and the average of the fifth harmonic voltage as identical as possible. By comparing them with actual sales data from an electric power company, we confirmed the feasibility of the assumed ratios.
Published Version
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