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In order to solve the harmonic suppression failure and harmonic surge in workshop distribution system caused by the fault of Active Power Filter (APF) bridge arm, a model predictive fault-tolerant control strategy was proposed. By analyzing the working principle of APF fault-tolerant transformation topology, the relationship of voltage vector transformation after fault-tolerant was revealed, and the prediction model of harmonic compensation current was established. A fast harmonic detection method based on the second-order generalized integral orthogonal generator (SOGI) was designed, and the harmonic compensation current output by SOGI was used as the reference instruction of the predictive control. According to the current predictive model and the reference instruction, in the rhombus voltage vector set of the fault tolerant APF, the switching state satisfying the minimum cost function was selected to carry out model predictive control and harmonic compensation. Experiments results verifed that, in the condition of the bridge arm fault, the proposed control strategy could work continuously and suppress harmonic current. The total harmonic distortion(THD) of the power distribution line is reduced from 9. 91% to 4. 87%, which verified that the proposed method can improve the reliability and fault tolerant capability of APF equipment in the cigarette factory. [ABSTRACT FROM AUTHOR]

In the three-phase four-wire power distribution system of modern cigarette workshops, the zero-sequence current causes the midpoint voltage fluctuation on the DC side, which affects the harmonic control effect of active power filter (APF). To solve this problem, a model predictive reconstructed space voltage vector control strategy based on neutral point clamped (NPC) three-level APF was proposed. The APF harmonic control hierarchy analysis framework was constructed, the three performance indicators of midpoint voltage balance, zero sequence current compensation and space voltage vector utilization were designed, and the performance of various voltage vector indicators was evaluated. The 6 types of reconstructed space voltage vector combinations were quantitatively compared, and the combination with the highest evaluation score in the analytic hierarchy process was selected for model predictive harmonic control. Simulation and experimental results showed that compared with conventional control strategies, the proposed strategy could effectively control harmonics and balance the midpoint voltage of the DC side of the APF. [ABSTRACT FROM AUTHOR]