APF Based On New Harmonic Detection And Fuzzy Control

The harmonic and reactive power current problems become serious increase because of the wide use of non-line loads in modern electric system.To resolve this problem,Active Power Filter is considered the best method as its high reaction speed and high self-adaptation ability with variational loads and system parameters.So APF's research and application are widely studied.This paper is focusing on harmonic detection and current tracking control.First,this thesis introduces the basic structure and principle of APF.The topologies of APF are series,parallel and mixed.There are voltage source APF and current source APF.In this thesis,it is voltage source parallel APF.Then,it emphatically introduces the main principle of instruction operational circuit and current tracking circuit.Second,this thesis introduces several ways of harmonic detecting.To the current expression,it proposes a new kind of quick harmonic detection method.This new method computes the harmonic current,active current and reactive current then separates them respectively though summators,multiplicators,and integrators.The advantage of this new method is that it has very simple structure but high precision and high responding speed.And its correctness has been verified by SIMULINK simulation.Third,there is an innovation in current tracking circuit design.It adopts fuzzy control technique.There are two fuzzy input variables.One is the error between command signal of compensation current and actual compensation current.Another one is the differential of this error.The output is the PWM modulation wave which controls the make-brake of IGBT.This technique improves APF's precision and adaptability.Forth,this thesis introduces the parameter design of APF.It emphasizes on how to calculate the value of output inductance and the DC capacitor in main circuit.At last,it is the simulation using MATLAB.There are two part of simulation. One is the new method of harmonic detection simulation.Another is whole APF simulation with new harmonic detection and fuzzy control techniques.The first simulation result shows that the new harmonic detection has fast dynamic response and high precision of distorted current detecting and it has high adaptive tracking detecting ability with variable loads.The second simulation result shows that the designed APF with new harmonic detection and fuzzy control technique can efficiently compensate the harmonic and reactive power and it can suit different kinds of loads.It also can improve the power factor and has favorable dynamic performance when the load current.