Research On The Simulation Of Lifting Wavelet Detection And Compensation Control Technology Of Shunt Active Power Filter

With the rapid progress of industry, a variety of power electronic equipment is widely used, which results in a more serious harmonic pollution. Active Power Filter(APF), a new type of harmonic suppression device with incomparable advantages, has become a hot topic.The further research is made on two pivotal techniques: detection of harmonic current and compensation control strategy of shunt active power filter(SAPF) in this paper. Firstly, the author introduced Instantaneous Reactive Power Theories based on the p-q theory, ip-iq harmonic detection method, then introduced the harmonic detection method based on wavelet transform. On the basis of the previous paper, a new online harmonic detection method is proposed, using the lifting wavelet transform with fast operation speed and simple structure, after the lifting of the current sampling signal sequence wavelet function using a new threshold de-noising wavelet coefficients, improve the denoising accuracy, continuity of the reconstructed signal is good. At the same time through the algorithm processes the signal sequence plus a sliding time window approach for online detection, and given the realization of the above line, decomposition, thresholding, reconstruction and other functions of S functions. Then study the current compensation control strategy most widely triangle wave comparison method and hysteresis current comparator compares the way, using PI control to stabilize the DC capacitor voltage, both in Matlab simulation to verify its effectiveness.Finally the article builds the whole simulation model in Matlab/ Simulink,harmonic detection algorithm using ip-iq method, wavelet analysis, lifting wavelet analysis method, compensation tracking control strategy using a comparison way of Hysteresis current and tracking harmonic current, and using PI control stable DC side voltage and current waveforms from the grid and spectrum after compensation, which verifies the correctness and validity of three harmonic detection and compensation algorithm tracking control strategy through simulation comparison. It shows the highest precision and the best mechanical capability of harmonic detection method based on lifting wavelet transform through simulation comparison.