Research And Application Of Active Power Filter Based On Dynamic Factor Adaptive Harmonic Detection

With the electrical equipments'high requirements for power quality, harmonic suppression and reactive power compensation are increasingly paid attention, and the basic theory of active power filter (Active Power Filter, APF) is matured, which has the function of harmonic suppression and reactive power compensation. It adopts modern power electronic technology, digital signal processing technology and advanced control theory, which is considered as the most effective and most promising ways to solve the harmonic pollution. Based on the comprehensive basis of relevant literature, it describes the course of development, current status and trends of active power filter in this thesis. It also introduces the classification of the active power filter's topology. In the thesis, it proposes the harmonic detection of single-phase parallel active power filter and control strategy as two main parts of research. In the end, simulation and experiment verify the validity and rationality of the methods above.Firstly, it introduces the development and research status of the active power filter, and gives a general discussion and conclusion on harmonic causes and the hazardous of the harmonic.Secondly, through the working principle of active power filter and characteristics of the analysis, three kinds of harmonic and reactive current detection methods are presented. For the traditional adaptive harmonic detection algorithm, it has to select the parameters between the desired step size and speed of convergence trade-off, which reduces the practicality of the algorithm. To overcome this problem, a novel Dynamic Factor Least Mean Square (DFLMS) algorithm is proposed for APF (Active Power Filter)'s harmonic current detection, which is based on adaptive noise cancellation technology and takes the single phase APF as a platform. With the consideration of poor performance of the traditional algorithm, the momentum term is introduced, and the error signal's mean estimate is used in the adjacent time point to control the updating of the step size, which greatly accelerates the convergence speed. A dynamic factor is introduced to not only accelerate the dynamic response speed, but also for re-mediation of the error term. Then it gives a detailed description of the basic principle and theoretical analysis of the DFLMS algorithm. Through the simulation and experiment, DFLMS algorithm and other adaptive harmonic detection methods were compared in active power filter application. On this basis, to improve the algorithm's performance, the multiple factor least mean square variable step size (Multi-Factor Least Mean Square, MFLMS) adaptive harmonic detection method is proposed. It increases the error signal adjacent shike static self-related factors on the right values and the impact of value iteration, which uses estimates of the error signal to control the time step update. It not only speeds up the dynamic response speed, but also reduces the steady-state offset in low SNR conditions. Finally, to improve the tracking accuracy, after a certain time, the error signal adjacent shike autocorrelation value and the value of the static weight of the iteration are increased, it proposes a limiting least mean square LMS (Limiting Least Mean Square, LLMS) variable step size adaptive harmonic detection algorithm. The results show that the three adaptive harmonic and reactive current detection methods are simpler, faster response and better steady state accuracy.Finally, the application research of the active power filter is realized. Based on the research of the main circuit of active power filter, it gives the selection principle of the power devices and the calculating of main circuit parameters. It makes the realization of the software based on the harmonic detection and current tracking control strategy, which provides a useful exploration for the practical application of active power filter.