Research On Harmonic And Reactive Currents Detection Method Of Hybrid Active Power Filter

With the increment of different kinds of non-linear load, theharmonic, reactive power and other power quality problems of powersystem are becoming more and more serious, the hybrid active powerfilter as power electronic device for harmonic and reactive power andother power quality problems, has drawn more and more attention both athome and abroad. The actual measurement results of harmonic andreactive current are the main basis for hybrid active power filter to handleharmonic and reactive power and other power quality problems, sostudying new harmonic and reactive current detection method,accelerating the speed of detection, improving the accuracy of detectionand adaptive capacity and further improving the performance of detectionmethods, have very important significance.Firstly, the hybrid active power filter is deeply studied. It analyzesthe working principle based on the topology and introduces severalcontrol method for power harmonic, reactive. Then according to theprinciple and detection requirements of the hybrid active power filter,analyzes recent harmonic and reactive current detection methods. Aimingat the subsistent problems of the present single phase harmonic currentdetection method, it proposes an improved single-phase harmonic currentdetection method without PLL. This method optimizes the original PLLby combining PLL and current average filter, greatly improves thedetection accuracy and dynamic response speed. In order to furtheraccelerate the dynamic response speed, the fundamental wave currentfeedback form is proposed. Two typical methods of the instantaneousreactive power theory are studied, based on the traditional ip-iq detection,an improved ip-iq algorithm is proposed, using sine and cosine signalcalculation block of fundamental positive-sequence voltage to reducedetected errors, using average filters to replace low-pass filters to reducethe delay. Aiming at the difficult that the traditional fixed step LMSharmonic current detection algorithm couldn’t reconcile detection speedand accuracy, it mainly introduces a improved SVSLMS harmonic current detection method, analyzes the causes of the steady-state error forharmonic current detection, redefines the feedback error, and further putsforward a new improved adaptive harmonic and reactive current detectionmethod. Simulation experiments shows that the method has a higherspeed and precision compared with the traditional LMS algorithm andSVSLMS algorithm.