Harmonic source identification by simultaneous-multipoint harmonic measurements

An identification of a harmonic source from voltage harmonics measured at outlets in a university campus is reported in this paper. A result obtained by a wide-area measurement shows that the major harmonic source is in a building. Another measurement is carried out within a building, and a rectification circuit is identified as a harmonic source. Each measured result is obtained by simultaneous-multipoint measurements using instruments developed by the authors. The harmonic voltages are determined by the current of the harmonic source and the line impedance of the distribution system. The location of the harmonic source is identified only from the voltages at outlets if a small voltage difference caused by the line impedance can be detected. The measured results clearly show the satisfactory accuracy and the effectiveness of the proposed instrument. The harmonic current ratio of the load is obtained from the voltage ratio between the voltage harmonics and the line impedance. The type of the load can be estimated from the measured harmonic voltage with a simple instrument for measuring a line-impedance developed by authors, because the current ratio is unique to each load.