Harmonic impedance measurement using three-phase transients

In this paper, a technique is presented for measuring the harmonic impedances of an unbalanced three-phase distribution feeder. The technique uses transients in bus voltages and feeder currents generated by several close-trip operations of the shunt capacitor bank. The work is based on the assumption that the impedance of feeder does not change over time during which the switching operations are performed. Mathematical development of the technique is verified with the laboratory and the field tests. The technique provided good measurements of the harmonic impedances up to 1.5 kHz for the given capacitor sizes. Statistical indices were developed to assess the accuracy of the estimated impedance values.