The Research On The Simulation Of Harmonic Current Detection And Control Technology Of Shunt Active Power Filter

Nowadays, power has become an indispensable part of human society with the development and progress of times, while the nonlinear electronic equipment's exist in power system makes the problem of how to improve the power quality more prominent In order to effectively eliminate the harmonic component in power system and purify power, active power filter APF (Active Power Filter) as a kind of power electronic devices which has excellent performance on harmonic suppression has received more and more attention.Firstly, it gives a general discussion on harmonic causes and the hazardous of the harmonic. After analysis of various types of active power filter, the paper adopts shunt APF as the research object according to its topological structure, principle of work.Secondly, The harmonic detection and control methods play a key role in the process of shunt APF, its performance has a direct influence on the effect of harmonic current compensation, so this paper makes research on the two methods. After briefly analyzing and comparison of several common current detection methods, this paper chooses a good adaptive ability and good versatility of adaptive harmonic current detection method. For the traditional LMS algorithm cannot trade-off the performance between convergence speed and steady-state accuracy, this paper proposes a variable step size algorithm, the new algorithm uses the average estimation of the current time and the previous time error signal to control the updating of step size, so that it can reduce the steady-state error and enhance the ability of anti noise; add dynamic factor to make small adjust of the step at convergence time, to further ensure the accuracy; at the same time it adds momentum term in the iterative formula of weights to speed up the convergence process. For the control method of shunt APF, this paper describes the two control methods of hysteresis control and voltage space vector control, based on a comprehensive analysis and consideration, a novel hysteresis current control method based on voltage space vector is proposed,use the hysteresis control to limit the current error, successfully limiting current error within the acceptable range; the method gets the reasonable switching of voltage vector using spatial distribution location of both the voltage vector and current vector.Finally, in the environment of Matlab/Simulink construct the whole simulation model of shunt active power filter with narameter design. the simulation results show that the harmonic detection and control method can quickly track the compensation current and effectively restrain harmonic.