Study On APF Compensating Current Control Method Based On Predictive Control

DC side of shunt active power filter commonly uses power capacitors as energy storage elements. In the process of controlling compensation current, there is the active power loss caused by the line resistance and switching losses which may lead to the DC bus voltage fluctuations. It will affect the compensation current tracking performance. Therefore, it is necessary to improve the control of the DC bus voltage and APF compensation current control. Good cooperation between them will be directly related to the harmonic current real-time tracking features, and it has a crucial role to improve the overall performance of active power filter.This paper focuses on the APF compensation current control and DC bus voltage control methods. Hysteresis control is representative of the non-linear control. The hardware is easy to implement, but its switching frequency is not fixed which results in the high loss too. Although this can be improved by changing the width of hysteresis, the current ripple can never be well suppressed. Aimed at this issue of the current control, this paper presents the compensation current control method based on predictive control. The basic idea of predictive control is to predict the future output state firstly, and then determine the current control actions. In predictive control, optimization is repeated. Predictive control has predictability and the advantage of a fixed switching frequency. DC bus voltage control using fuzzy PI compound control method also has the simple structure and high accuracy of PI control, and advantages of fuzzy control that does not depend on the system model parameters. With the simple algorithm, fast dynamic response and small static error characteristics, it gives full play to the advantages of fuzzy control and PI control. Simulation proves that system overall control performance has improved with good coordination between compensation current control and DC bus voltage control. This good control algorithm for improving the performance of APF system has great theoretical and practical significance.