Research On Predictive Current Control Method Of Three-phase Shunt Active Power Filter

Due to the increasing number of nonlinear loads in power systems, the harm produced by harmonic pollution have been more and more serious in aspects of generate, utilize of electricity, and use of some equipments. The Active Power Filter(APF) is regarded as the most effective method to solve these issue as it could manage harmonic pollution, compensate reactive power, and balance three-phase current. Meanwhile, APF in parallel has been used widely as its high reliability and flexible configuration. While the effectiveness of an APF is highly rely on the control algorithm of current tracking which has been emphasis discussed in the thesis. The content mainly includes:(1)Some key factors related to the performance of an APF have been discussed by establishing mathematic model of APF in parallel based on two phase rotating coordinate. Isolate harmonic element with help of Sliding window Fourier transform. Add active power current to current close loop, and get a little fundamental component to ensure the constant of voltage in DC side to avoid the impact to following feature of current. Besides, PR control was used to precise control sine signal in different frequency, and to realize the tracking control on fundamental component by using integration control. Use SPWM to minimize the THD of output voltage.(2) Predictive control combine with reference current prediction and model prediction based on PR have been proposed, it compensate the delay of an APF and ensure the stability of an APF greatly by predict the current and voltage for about one cycle. To design PR coefficient by precision of compensation, and design integration coefficient by the demand of phase margin. And use piecewise function and sliding window average algorithm to fit reactance to reduce the impact on precise caused by errors in model. Compared with traditional ones, the harmonic compensate method proposed in this thesis is better, which have been proven by both theoretical analysis and simulation.(3) Design methods of parameters of main circuit and control circuit have been discussed here. Design optimum parameters and circuit from aspects of cost, performance, and practicability. And to choose DC voltage and capacitors due to the allowable voltage ripple. Parameters have been chosen by considering higher harmonics produced by switch on-off and a damp have been added to the capacitor to avoid resonance.(4) An APF experimental platform based on predict current control has been set up, and the tester is based on F28335 chip, regarded FF300R12KT14 as power amplify module. The stability of the proposed current tracking method and the advantage of harmonic compensate have been proved by experimental results.