Frequency-Domain Harmonic Modeling of a Six-Pulse Rectifier Under Various Power Supply Conditions

With the development of power systems towards power electronics, the integration capacity of renewable energy into the grid has been significantly enhanced. The power system is progressing towards modernization, intelligence, and sustainability. However, the integration of large-scale power electronic loads has also led to certain power quality issues in the grid, affecting the stable operation of the power network. Addressing the harmonic issues in power quality, this paper investigates the harmonic source model of a thyristor-based six-pulse rectifier and constructs its frequency domain harmonic model under different power supply conditions. First, the characteristic harmonic coupling admittance matrix model of the rectifier load under ideal power supply conditions is studied and established. On this basis, the non-characteristic harmonic coupling admittance matrix model of the rectifier load under unbalanced power supply conditions is developed. The unbalanced component detection method based on the Second-Order Generalized Integrator (SOGI) is utilized to detect and assess the three-phase balance. Ultimately, a harmonic model of the six-pulse rectifier adaptable to various power supply conditions is constructed. The accuracy and effectiveness of the proposed model are validated through MATLAB/Simulink simulations.