Frequency Tracking And Real-time Harmonic Detection Based On PLS Algorithm

Power system frequency is a very important parameter for evaluating the quality of the whole grid.Once the frequency collapsed,it would be harm greatly in the power system.The influence of the load change and other factors,in the power grid,will produce harmonic pollution,affect the power quality.Therefore,it has important practical significance to frequency tracking and real-time harmonic detection in real time.In real-time tracking of power system frequency,due to the presence of harmonics and noise in the voltage signal,adaptive FIR band pass filter is designed in this paper to filter the voltage signal,and the experiment simulation in MATLAB was made.The simulation results show that the anti filter harmonic and noise interference,used for filtering of the voltage signal is reasonable and feasible.In real-time tracking of power system frequency,the recursive partial least squares(Recursive partial least squares,Abbreviation: RPLS)algorithm was proposed to realize the tracking of the power system frequency.Ordinary RPLS algorithm in every model calibration will continue to obtain the parameter matrix model and the new data matrix combined to constitute a new combined sample for the implementation of recursive computation,which has led to old data that are used repeatedly,thus which affects the accuracy of frequency measurement;And RPLS algorithm based on sliding window in frequency occur mutation in the absence or in impure voltage signal,it has the delay time long,measuring frequency error is large,it is difficult to achieve real-time and accurate frequency measurement.In view of the above problems,an improved RPLS algorithm was proposed,which combines the method of forgetting factor and sliding window to realize the real-time detection of power system frequency,among them,different forgetting factors are combined with the residual matrix and the new data block matrix inthe recursive equation,which is the key to realize the accurate and real time tracking frequency.The experiment simulation in MATLAB was given.By simulation results,the tracking error of the algorithm is small,its convergence rate is fast,and its calculation is small,it can realize the real-time detection of power system frequency,which has certain application value.Aiming at the problem of power system harmonic,sliding window PLS algorithm is used to realize real-time harmonic detection.Based on the RPLS algorithm,this algorithm uses the sliding window PLS algorithm to detect the amplitude and phase of the fundamental wave and harmonics in real time.Simulation results are known by MATLAB,the proposed algorithm can achieve high efficiency and fast harmonic analysis.