shinenanax.blogg.se

If the harmonic source is unbalanced and the load remains balanced the line voltages and currents in the motor section are unaffected by the injected triplen harmonics. The results show that if the harmonic source and the load is balanced, the line voltages and 6k ± 1 harmonic currents in the motor section are symmetrical sets. Only one SCS per harmonic frequency is applied to the motor.

the harmonic flows may resolve to one, two or three symmetrical component sets and this depends upon the type of three-phase set found at a given point/node in a system. The results show that what is injected in terms of symmetrical component sets by a harmonic source is not necessarily received by the system, i.e. The new terminology/subclasses of three-phase sets introduced distinguish balanced and unbalanced harmonic sources from each other and are found suitable for comparing injections to harmonic flows in systems in terms of symmetrical components. The positive, negative and zero sequence symmetrical components injected by an unbalanced harmonic source have different frequencies. The role that the symmetrical set plays in harmonic analysis and in the modelling of harmonic sources should not be ignored.Ĭlassically, positive, negative and zero sequence components have the same frequency. In general authors of power system literature ignore the symmetrical set concept as opposed to the asymmetrical set. 1 does not adequately describe the relationship between harmonics and symmetrical components, especially harmonic sources and does not cover unbalanced loads. The results from four case studies show that these subclasses and their resolution to symmetrical component sets improve understanding of harmonic analysis of systems having balanced and unbalanced harmonic sources and loads. Subclasses are introduced with the names symmetrical balanced sets, symmetrical unbalanced sets, asymmetrical balanced sets and asymmetrical unbalanced sets to show that a threephase set can resolve to either one, two or three symmetrical component sets. Three-phase sets are classified in terms of symmetrical sets and asymmetrical sets. New terminology is introduced to make clear the relationship between harmonics and symmetrical components.