Research On The New Detecting Method Of Basic Wave And Harmonic Waves

The new methods of fundamental wave and harmonic detection.The experimental results indicate that the New fundamental wave and harmonic detection method not only has good noise immunity,and has a high accuracy of test results.There is great significance for power system security,economic and stable operation.This paper from the following three aspects of research on the new detecting method of basic wave and harmonic waves.1).In this paper,we study a model based on modified Duffing oscillator fundamental frequency of the signal detection method.Compared with the traditional model,the model the critical chaotic amplitude not with the change of excitation frequency of oscillator and the sampling frequency,besides,it has a high accuracy of test results and good noise immunity.Thus it effectively avoid the existing Duffing oscillator can only detect the fundamental limits of low frequency signal.and greatly expanded the frequency band of the signal to be detected,but improved the Duffing oscillator detection model,poor real-time performance and it is difficult to accurately detect the wave phase.2).In this paper,we study a model based on the curve fitting method of Hermite polynomial.We obtain the best curve fitting model through Hermite polynomial.Then detecting bacis wave with passing zero,the simulation results show that the detection method of test result accuracy up to 1e-10 with out noise pollution,the test result accuracy is 1e-6with noise which the SNR is 60 dB noise signal.3).Using the recursive least squares(RLS)to obtain the optimal model parameters which is the fourier series model after established the model of the harmonic signal,and then obtain the fundamental wave and every harmonic amplitude and phase.The simulation results show that the amplitude the detection accuracy of result is 1e-4 under the SNR is 60 dB noise background.Considering the effectiveness of the detection under strong noise,therefore,we study the way of detection of harmonic is significant on the actual application value.