Harmonic state estimation in power distribution network using improved complex independent component analysis

Independent component analysis (ICA) can obtain the harmonic current without the harmonic impendence parameters, but it´s not capable of estimating the amplitude of harmonic current accurately. However, to effectively estimate the harmonic state of power network and analyze the harmoic distortion level, the amplitude of harmonic current is very important. In order to solving the problem abrove, a scale factor calculation method based on complex ICA is proposed in this paper to estimate the amplitude and phase of harmonic current. The initial harmonic current phasor is obtained through complex ICA, whose amplitude and phase is unknown. Then considering the fact that the system equivalent impedance is much less than the load impedance, the harmonic current injected into the network most is flowing into the system. Therefore, the harmonic current flowing into the linear loads can be ignored. The calculation methods in two different situations of the scale factor are derived. According to the scale factors, the amplitude and phase of harmonic current can be calculated. The proposed method is verified by computer sumulations for the IEEE 14-bus distribution network, and practical calculations for a local network. In the case studies, the contrast is conducted between the proposed method and the complex ICA. Experimental results show that the proposed method can calculate the amplitude and phase of harmonic current accurately without harmonic impendence.