Research On Shunt Active Power Filter Harmonic Detection And Compensation Strategy

Recently,with the extensive usage of nonlinear load in industrial production,the pollution of power system is getting from bad to worse.The power quality of power system,therefore,has drawn great concern.A variety of electrical equipment have been developed to improve the power quality and active power filter is one of the most powerful tools for power quality improvement and harmonic compensation.Active power filter harmonic current detection capability and switching loss problems will directly affect the performance of the filter.Therefore,this thesis mainly focus on harmonic detection technology and switching loss problems of Shunt Active Power Filter and provide a in-depth study.This thesis put forward a new harmonic detection algorithm and new solution for switching loss problem.Meanwhile the thesis discuss the the shunt APF main circuit topology,the main circuit parameters and the control strategies compensation current tracking.This thesis starts with an extensive research of the topology of the shunt active power filter and the analysis of working principle.The problems exist in active power filter are put forward which provides a theoretical basis for the following analysis.Harmonic detection accuracy and real time are two critical factors to measure active power filter performance.For the compensation of high variation frequence loads,traditional harmonic detection algorithm can not achieve fast dynamic response.Therefore this thesis put forward a new harmonic current detection algorithm base on recursive least squares(RLS)algorithm.Compared with traditional algorithm,the improve harmonic current detection algorithm effectively improve the dynamic response of active power filter.For the switching loss of APF main circuit,the thesis focus on both the switching frequence and the switch on-state current.A switch control policy based on discontinuous PWM is proposed in the thesis to reduce the switching frequency of the main circuit while maintaining harmonic compensation capability of APF.By clamping switches this control tactics minimize switch on-state current and therefore reduce main circuit switch loss in the largest extent.The feasibility and effectiveness of this tactics is verified through simulation.Finally,experimental platform of APF system based on DSP is built up.Software programming and hardware parameters selection are illustrated.Experiment results of this platform indicate that this platform based on the tactics proposed in this thesis can effectively compensate harmonic current and satisfy the expected requirement...