Research On Hybrid-shunt Active Power Filter

With the development and improvement of power electronic technology，a variety ofpower conversion devices such as current converting equipment are used in every field. Theaddition of the nonlinear loads in the power system affects the quality of the modern powergrid seriously. Therefore, it is urgent to solve the problem of harmonic elimination. Thetechnology of active power filter trends to be effective solution to the harmonic currentpollution. The subject aims to study the harmonic current detection and control method inorder to improve the harmonics compensation performance of the active power filter.The current detection method based on instantaneous reactive power reflects a tradeoffbetween maladjustment and the speed of dynamic response. The LPF affects the speed ofcurrent detection. This paper proposes adaptive filter as LPF on harmonic detection circuit.An improved algorithm is proposed in this paper. The variable is introduced and coherenceaverage estimation of error signal is used to control the updating of the step size, whichgreatly increases the convergence speed. This new current detection method validate thebetter dynamic performance and maladjustment.After obtain reference signals by the improved variable step-size algorithm, this paperstudies the current tracking control algorithm. In order to realize zero-error-control, thegeneralized integrator is introduced into the current controller of active power filter.Additionally, a fuzzy adjustor and a predictive current controller is designed. The fuzzyadjustor is to improve the robustness of current controller through modifying parameters ofthe generalized generator for the active power filter. And the predictive current controller isproposed to solve the delay problem in the control system. A discrete model of the system isestablish and the reference current are obtained by using Lagrange interpolation formula.Then one step ahead prediction value of the reference current is calculated. Thus bothexcellent steady performance and fast dynamic response can be obtained.In this paper, the capacities of active power filter and DC-link voltage characteristics ofhybrid active power filters are derived. In order to minimize the capacity of its active powerfilters, a novel optimal design method is proposed for the single-tuned hybrid active powerfilters on that basis.This paper simulates the HAPF with MATLAB/SIMULINK. The results demonstrate theavailability of the method mentioned before.