Harmonic state estimation in distribution network based on fifth harmonic current characteristic

Reproductive simulation of the measurement data by the harmonic analyze is start point to understand harmonic voltage distortion mechanism, but the method to estimate the harmonics distribution among the many utility customers has not been established. In the last decade, harmonic analysis of Japanese middle voltage customer and low voltage customer has been done, the distribution of the fifth harmonic current can be classified middle voltage customer´s single phase load, low voltage customer´s three phase and single phase load named group A and middle voltage three phase load named group B, and the amplitude per load kW has been investigated from sum of each current vector. By the application of this knowledge, there is a possibility to estimate the harmonic distribution with many harmonic source in the distribution network. In this paper, we developed a harmonic state estimation method with limited measurement condition by using the fifth harmonic current phase angle classification model. Numerical experiments are conducted in seven node distribution network to test the proposed method. The results show that the proposed harmonic state estimation by using the fifth harmonic current phase angle classification model approach can reliably identify harmonic distribution in the change of load conditions, background harmonic voltage phase angle and series inductance of shunt capacitors.