| In recent years, many attentions have been focused on the power quality due to the wide use of power electronics and due to the increasing non-linear loads in power system. Harmonic has become an important element of impacting power quality in power system, and the identifying and location of the harmonic sources are the necessary task for the detection and management of the harmonics. To determine whether harmonic sources exist in the load is of essential importance for improving and managing the affect of the harmonics on power system.In this paper, the localization and detection methods of harmonic sources in power distribution network are systematically described, and their advantages and shortcomings are also analyzed. Additionally, based on the partial least-squares regression for assessing harmonic impedance and the harmonic emission level, and employing both GPS(Global Position System) and PMU(Phase Measurement Unit) techniques, a method of improving the monitor of the harmonic in real time has been presented. This method can be outlined as the following analysis steps. First, the Thevenin equivalent and Norton equivalent are, respectively, used for the system and the customer, and than the regression equations can be obtained from the system parameters. Secondly, harmonic voltage and harmonic current are synchronously measured by using GPS and PMU techniques, the regression coefficients are calculated by means of the partial least-squares algorithm, and the harmonic impedance of the system is therefore given with the use of the calculated regression coefficients. Finally, the harmonic emission level of the customer and the system background harmonic can be obtained. According to the present method, the corresponding model is constructed and the simulations have been carried out, indicating that the proposed method is feasible for monitoring the harmonics in real time in power distribution network. |
