The Harmonic Current Detection And Digital Realization In Active Power Filter

The harmonic current detection is a key component of the active power filter. The speed and precision of the detection determine the performance of the active power filter to a large extent. In addition, according to the different applications of the active power filter, the requirements for the harmonic current detection is also different, it only needs to detect the total harmonic current some simple occasion. In order to use the minimal capacity and loss to achieve the best compensation effect, the high power applications often need to detect the part of the harmonic current for selective compensation. This thesis will analysis and do a research on the related issues of harmonic current detection under this background.First of all, the generation and harm of current harmonic, harmonic current detection of the main technology will be introduced, and the digital signal processing related issues are described. The theory of instantaneous reactive power is introduced in detail, and the application of rotating coordinate transformation is introduced in order to detect the k-th harmonic current. The selection of the low pass filter in the process of transformation is analyzed. Followed by the introduction of the adaptive trap filter harmonic detection principle, and for the multiple harmonic current detection. The feasibility to combine the two detection methods of the rotating coordinate transformation and adaptive notch filter for detecting harmonic currents is described, given the relevant analysis and simulation results. At the end of this thesis, based on the study of harmonic current detection technology, the detection system of digital achieve are discussed, and the efficiency, stability and accuracy of each module of the system in the FPGA digital signal realization are analyzed and optimized, which will reduce the consumption of hardware resources and improve the accuracy and real-time of the detection. The related experiments are carried out on the platform of the active power filter. The results of the experiments also show the feasibility of the method by this thesis.