Study On Compensation Current Control Method For APF Based On Repetitive Control

Today, as economic globalization develops in depth, applications of power electronic technology promotes the rapid development of many industries. But, at the same time, power electronic equipment and nonlinear loads injected a great amount of harmonic and reactive currents into the power system, which cause power quality problems. Because of its significance and urgency, the harmonic problems in power system, which attracted more and more attention of domestic and foreign scholars, have great value in theory and practical significance.Currently, active power filter (APF), which considered to be one of the most effective means of power harmonic suppression, having the widespread research and application prospect, becomes one of the study hotspots in the field of power electronic technology. At present, the study of APF topology, harmonic current detection and compensation current control method is the main direction of APF research. First of all, this paper introduces the classification of the APF, and analyzes the topology structure and work principle of shunt active power filter with three-phase and three-wire. Based on the system structure features, set up APF mathematical mode and give the harmonic current detection method and structure diagram.For active power filter, the control accuracy of the compensating current directly determines the result of current compensation. The key for improving the compensation precision is how to make the compensating current tracking the reference current better and reduce the tracking error. While the traditional PID control system is not effective, Repetitive controller, which based on internal model control (IMC), can completely eliminate the system steady-state error in theory.After the performance analyses of repetitive controller, to enhance stability and tracking performance, this paper improves the classical repetitive controller by introducing improved IMC compensator, which improves tracking performance while stability is guaranteed. For the characteristic of quickly dynamic response of PI controller, this paper combine PI controller with repetitive controller to improve the dynamic response. And respectively study and design two controller systems of series-coupled and parallel-coupled.Finally, the paper designs the model and simulation of shunt active power filter by MATLAB/Simulink simulation software. The simulation results, having be analyzed and compared, prove that the compensational precision and dynamic response speed of APF system can be enhanced by compound control strategy based on repetitive control. So the feasibility and correctness of this strategy were verified by simulation results.