In recent years, due to the continuous connection of high-power power electronic devices and other large capacity and nonlinear loads to the power grid, the low-frequency harmonics caused by these devices have seriously affected the power quality of the power grid. This paper proposes a design scheme for large-capacity low-frequency AC power supply based on thyristor AC/AC inverter. On the basis of controlling phase angle α , control of pulse width β was added, and a simulation model of a three-phase six pulse dual variable AC-AC frequency conversion closed-loop system was built in MATLAB/Simulink environment to verify its output effect in the thyristor AC-AC frequency conversion system. The power scheme can be used to simulate low-frequency interharmonics in the output power supply system, providing a fundamental platform for conducting low-frequency interharmonics research.

Low-frequency interharmonics;Large-capacity low-frequency AC power supply;AC-AC frequency conversion;Bivariate control theory;Cosine intersection method