Research On Harmonic Analysis And Control Method Of Intermediate Frequency Power Supply Based On Adaptive Algorithm

With the increase of nonlinear load in power system,the harmonic pollution of power supply system is becoming serious,and it directly affects the quality of power supply.Therefore,it is urgent to adopt appropriate harmonic detection and rejection control methods so that the impact on the quality of power supply can be avoided or reduced.However,due to the limitation of the traditional passive filter,the harmonic control method based on the traditional passive filter can't meet the requirements of harmonic control.With the wide application of high power electronic devices,the active filtering technology has been developed rapidly.The active filter is a kind of electronic device of dynamic compensation of harmonics and reactive power.The compensation effect will not be influenced by the change of amplitude and frequency,and the change of reactive power has small impact on it,Meanwhile,it can improve the shortcomings on the passive filter in harmonic compensation,and it has become the most widely used harmonic means.By analyzing and comparing the characteristics of the harmonic current detection algorithm based on LMS and the existing variable step LMS harmonic current detection algorithm,the variable step size LMS adaptive distortion current detection algorithm based on double versiera functions proposed in this paper.The algorithm uses the autocorrelation time mean estimation of the error signal to eliminate the interference on distorted current to step update,and adjusts the step size and momentum in the weight update by the versiera function,that is by changing the parameters of step size and momentum in the weight update formula,step size and momentum term have a great influence on updating the weight formula at the beginning of the system or when it has a mutation.As the system reaches steady state,the step size and momentum term converge to small values,which reduces the influence on the update of the weight formula.This method can not only improve the convergence rate of the algorithm,but also reduce the steady-state error of the algorithm.Moreover,the proposed algorithm has good tracking ability.The timing comparison of hysteresis current control for tracking control of compensation current is employed to ensure that the output current can track the command signal.Meanwhile,DC side voltage control link is added in the control system for controlling the active power flow between the main circuit and the power grid,and maintaining the stability of the DC voltage of main circuit.The Matlab/Simulink is used to carry on the simulations for the proposed harmonic current detection algorithm and rejection control method.The simulation results show that the harmonic current detection algorithm and its control method can realize the detection and control of the harmonic current generated in the intermediate frequency power supply and similar system.