Research On The Application Of Wavelet Transform And Prony Technique In The Detection Of Power Quality

With the rapid development of techniques and national economy, and the widely application of modern power electronics techniques, more and more attention has been paid to power quality (PQ) by both suppliers and consumers of electricity. In order to improve the PQ, some measures should been taken to detect, estimate and identify different disturbances accurately. Based on this, the method of the detection and identification of PQ is discussed and studied in this paper.Firstly, the wavelet transform is used to analyze the PQ transient because of its good time-frequency localization. While the Prony technique is applied to estimate the frequency, phase, and magnitude of each component of the static PQ signal because of its excellent ability in the frequency resolution. The simulation results show the accuracy and effectiveness of the methods above.Then, a comprehensive algorithm, based on the wavelet transform, RMS, and the Prony technique, is proposed to identify and analyze the PQ problems including sags, swells, interruptions, impulses, oscillations, harmonics, inter-harmonics and flickers. Many cases prove that the proposed algorithm can identify and analyze typical PQ disturbance effectively, and it has the advantages of simplicity, directness, recognition of many-kind of signal and high recognition accuracy.In addition, an efficient method based on the Prony technique and Hilbert transform is presented to track the voltage flicker envelope. The Prony technique is used to analyze the flicker signal, and then the original signal and its hilbert transform are reconstructed. According to the principle of envelop detection, the envelope of the flicker signal is obtained. Moreover, the effect of harmonics to the flicker envelope tracking is analyzed. Simulation results show the accuracy and effectiveness of the proposed algorithm.Finally, a PQ monitoring instrument based on DSP and ARM9 is studied.