Research On Key Technologies Of Shunt Active Power Filter Based On Repetitive Control

With the rapid development of modern electronic technology,more and more electronic equipment is produced in the power system,more and more harmonics are added to the power grid,which is a great threat to the security of the power system.The shunt active power filter(Shunt Active Power Filter,abbreviation SAPF)is the mission of the harmonic suppression and reactive power compensation,has been studied by many scholars.In this paper,we study the key technology of three-phase four-wire system capacitor midpoint Shunt Active Power Filter,mainly include:LCL output filter design,harmonic current detection method,current tracking control technique,3D-SVPWM algorithm,design of dc side voltage and control technology.In view of the existing in the harmonic current detection delay and steady state accuracy problem,put forward an ip-iq new method for the detection without phase locked loop.Characteristic of the new method is:by default transformation matrix C and frequency ? to realize harmonic current and fundamental current detection;Using the fundamental current feedback,dynamic response time decreased from 1.3 period to 0.8 period;With low pass filter and mean filter cascading of high performance low pass filter,can obtain the best detection precision and response speed.In addition,this paper has deduced the SAPF mathematical model of three-phase four-wire system capacitor midpoint,and by mathematical model deduced a kind of optimization of 3D-SVPWM algorithm,the algorithm is to get rid of the tradition 3D-SVPWM algorithm of ABC coordinate to a??? coordinate transformation,space vector of the sector judgement,the sector basic space vector duty ratio calculation,but directly sit at ABC coordinate to calculate duty ratio control each bridge arm switch on and off of the device.For the existence of larger resistance power loss and low frequency oscillation in the LCL filter,put forward a split capacitor LCL filter;the filter capacitor C is divided into two capacitors C1 and C2,the only in which a capacitor branch series damping resistors.A high performance repetitive controller is proposed to realize the non static error tracking of the command current in the current tracking process.First make PI controller series repetitive controller and again after the series controller parallel other repetitive controller.When error suddenly increase,PI controller adjust action immediately,repetitive controller began to function after half fundamental period;When little error,PI controller is almost no effect,only by the repetitive controller,which has the best dynamic performance and tracking accuracy.To reduce the switching loss and power loss of the control system,this article with the aid of mathematical theory of three-phase four-wire system deduced strictly SAPF control system the dc side of the normal work of the minimum voltage.In the end,the proposed theory is simulated by Matlab,and the simulation waveforms and data are analyzed in detail,which verifies the accuracy and effectiveness of the proposed theory.