Abstract:

Four-arm active power filter(APF) is an ideal device to the power quality of three-phase four-wire distribution network. Owing to the sufficient number of base vectors, three-level four-arm APF has better current tracking performance, but the prediction calculation amount is too large when model predictive current control is applied. A model prediction voltage control strategy based on the idea of space stratification is proposed. Based on the deadbeat control idea and the discrete mathematical model in αβγ coordinate system, the expected reference voltage is predicted from the reference current, and the multiple current predictions are converted into the single voltage prediction. Combined with the law of three-level four-arm APF voltage vector space distribution, the idea of space stratification is adopted, and the optimal vector range is selected based on the spatial position of γ-axis. The optimal vector range is reduced from the traditional 81 to 4~18, and the voltage jump limit and the control of neutral-point potential are realized. Simulation results show that the strategy has excellent control performance.

Key words: three-phase four-wire system, three-level four-arm, predictive computation, model predictive voltage control, deadbeat control, space stratification