Determining the Responsibility of Three-Phase Unbalanced Sources Based on RICA

Abstract

Voltage unbalance is one of the main power quality problems, and the source of many negative effects on utilities that are experienced by customers. In this paper, a method based on robust independent component analysis (RICA) for responsibility division of unbalanced sources is proposed for voltage unbalance. According to the weak correlation between negative-sequence voltage and upstream and downstream current fluctuation at the point of common coupling (PCC), the independent component of the negative-sequence voltage and current fluctuation at the point of common coupling is obtained by RICA. The blind source mixing coefficient matrix can be obtained according to the least squares method. The equivalent negative-sequence impedance on both sides of the PCC can be obtained using the linear correlation between the mixing coefficients. Finally, according to the principle of partial pressure, the unbalance contribution of the upstream and downstream at the PCC is calculated. The method is accurate for upstream and downstream impedance estimation compared with the traditional method, and has a strong anti-interference ability. When the background noise or system fluctuation is large, the responsibility division result is still accurate. The correctness and effectiveness of the proposed method are proven by the simulation of the experimental circuit.

Unbalanced responsibility division considering renewable energy integration

“…At present, commonly used unbalanced responsibility division methods are divided into three categories: network parameter method [12–17], measured data method [18, 19] and blind source separation (BSS) method [20].…”

“…As the equivalent negative sequence current sources on the system side and the load side change relatively independently, the BSS method provides a new idea for the division of unbalanced responsibilities. In [20], robust independent component analysis (RICA) was proposed to calculate the system and load impedance, and then the unbalanced voltage contribution is calculated based on the voltage and current. However, when renewable energy is connected to the grid, the system and the load are not statistically independent of each other, and the calculation error of the RICA method is large.…”