Waveform Correlation Based Harmonic Voltage Contribution Determination of Iron and Steel Plants Supplied From PCC

In this research work, a new method which determines the individual harmonic voltage contributions of the EAF plants supplied from a point of common coupling (PCC) to the PCC voltage is presented. EAFs are one of the most significant sources of the harmonics, especially the uncharacteristic ones, therefore it is important to be able to discriminate the amount of individual contributions from the feeders of a PCC supplying multiple EAFs. The proposed method uses the relationship derived between the correlation coefficient of the PCC voltage and the feeder current waveforms and the harmonic voltage contribution of each plant supplied from the PCC. The main idea is based on the fact that harmonic voltage at the PCC is a result of the additive effect of voltage drops on the source side impedance of the power system caused by the individual feeder currents. After computing the Pearson correlation coefficients at each harmonic frequency using 10-cycle synchronized feeder current and PCC voltage waveforms, harmonic voltage contribution of the related feeder is obtained using the proposed method. This procedure can be repeatedly used to obtain the contribution of each EAF plant at each frequency component. Field measurements from a PCC supplying multiple EAF plants are used to verify the results and the performance is compared with the previously proposed methods. With a specified source side impedance by the utility, the proposed approach is a fast method of obtaining the harmonic responsibilities, since no real-time impedance measurements are required and no need for the measurements of the other feeders to compute the contribution of a specific feeder in contrast to some other methods. The proposed method can be easily adapted as a real time harmonic contribution detection tool for the power quality analyzers, all of which have synchronized voltage and current waveform measurements.

Keyword: electric arc furnace; electrical power quality; harmonic voltage contribution; point of common coupling; power quality