Identification of harmonic current contributions of iron and steel plants based on time-synchronized field measurements — Part II: Inside plants

This is the second of a two-paper series, in which the field-data-based analytical method proposed in Part-I has been extended to determine the amount of harmonic currents sunk by the shunt harmonic filters of the Iron and Steel (I&S) Plants from the rest of the system. The non-linear characteristics of the plants and the utility are modeled as harmonic current sources, whereas the linear parts of the proposed extended model consist of passive circuit elements, with the harmonic filter RLC circuit parameters also integrated into the model. This extended method, which can also be used for harmonic contribution assessments, requires sample-by-sample, time-synchronized harmonic current measurements inside the plants and at the point of common coupling (PCC). It eliminates the need for harmonic voltage measurements at the expense of the need for inside-plant measurements. It has been verified both by computer simulations and by application on field data. The results have shown that the proposed method is a successful tool to determine the magnitude of harmonic currents which are sunk by the harmonic filters of I&S Plants connected to the PCC, especially when measured harmonic currents of I&S Plants exceed the actual contributions.