An Unbalanced Component Detection Method and Compensation Strategy Based on Second-Order Generalized Integrator (SOGI)

The detection method of three-phase unbalance component on the load-side has become a research hotspot to achieve unbalanced load compensation. In this paper, a novel three-phase unbalanced component detection method and compensation strategy is proposed by applying the second-order generalized integrator (SOGI), so as to realize the decoupling improvement of current coupling problems in traditional positive and negative sequence dq transform detection method. Fast extraction of unbalanced components can be thus achieved, by calculating the positive and negative sequence currents on basis of orthogonally transforming αβ components separately. Furthermore, an average filter is adopted to solve the phase shift problem in low-pass filter and improve the detection accuracy. By modeling a three-phase three-wire system with APF, the three-phase load unbalance compensation before and after harmonic load switching is thoroughly analyzed. The simulation result verifies the feasibility and accuracy of the proposed detection method.