Background harmonic modeling and harmonic contribution assessment for large-power industrial supply system

The large-power rectifier system injects numerous harmonics into the public grid, which results in serious effects on the power quality at the point of common coupling (PCC). The two methods, (1) establishment of the accurate probabilistic model for the background harmonics and (2) assessment of the harmonic contribution, are beneficial for evaluating the impact of the harmonics generated by the power consumer on the power grid. First, the background of the power supply system and the harmonic distribution at the PCC are introduced, based on the measured data in the electrolytic manganese factory. The probability distribution of the harmonic voltage during the specific discontinued day is fitted by means of the normal distribution, the lognormal distribution and the Weibull distribution. The goodness-of-fit is obtained by Kolmogrov-Smirnov test method, and the optimal fitting function is identified. The simulation model of the background harmonic voltage is thus built. Finally, the harmonic contribution of the rectifier system on the production day is assessed based on the simulation model. The results show that, the negative harmonic contribution is dominating.