Harmonic oscillation analysis and stabilization method comparison of shunt active power filter in full compensation mode

The harmonic compensation of SAPF (shunt active power filter) may trigger harmonic oscillation due to the interaction with grid impedance and non-linear loads, which distorts the power quality. In previous research, the relevant mechanism has been studied. However, the SAPF generally employs complex harmonic detection algorithm, which significantly increases the computational demands. The SAPF in full compensation mode can effectively solve this problem. But the modification of harmonic detection link may change the oscillation mechanism and previous stabilization methods need to be re-evaluated. Therefore, this paper establishes the small signal model of the SAPF system in full compensation mode and investigates its oscillation mechanism. It is revealed that harmonic compensation and passive resonance collectively induce the harmonic oscillation. Based on the model, the working mechanism and application performance of the main stabilization methods proposed in the past (harmonic virtual admittance and harmonic compensation canceling) are analyzed and compared. However, neither of them can achieve effective stabilization without sacrificing the performance of compensation. Consequently, the harmonic phase compensation method is proposed to achieve the stabilization of the SAPF system in full compensation mode without affecting normal compensation. Finally, simulations and experiments are performed to verify the mechanism analysis and proposed methods.