A METHODOLOGY FOR ASSESSMENT OF HARMONIC IMPACT AND COMPLIANCE WITH STANDARDS FOR DISTRIBUTION-SYSTEMS

Many problems related to harmonic signals in power systems occur at the distribution voltage level. Large commercial, industrial, or institional sites may contain loads whose demand currents are nonsinusoidal. The harmonic content of these load currents may couple with other loads on the same feeder or loads on different feeders energized by the same transformer. The new IEEE Standard 519 specifies maximum harmonic signal levels at points of common coupling to the electric utility. We find these standards to be applicable within industrial and institutional sites. A state estimation methodology is illustrated for the calculation of harmonic current and voltage distortion at all busses in a distribution system. It is recommended to check these distortion levels for compliance with the Standard 519. The paper also gives an interesting calculation of the total harmonic distortion of an ideal converter current. New approximations are also introduced for the bus impedance matrix at frequency h-omega-0. The approximations are developed from power series expansions in either frequency, omega, or inverse complex frequency, (j-omega)-1. The convergence of the series is studied in terms of Banach's lemma.