Study Of Detecting Power Harmonic By Eliminating Singularity Point

Power quality has been appeared since the inception of power system. The topics of power quality have risen to the forefront because of an increase in wide-ranging electronically controlled equipment. Harmonic, as one of the important aspect in power quality, has become very evident with the non-linear load increasing. It has great harmful effect on electric equipments and devices in the system. In order to supervise the system status and restrain harmonic disturbance, accurate harmonic measure has become a pivotal problem. The analysis objects in power system are very complicated, there are a lot of noise and breaks which indicate system's operation status in voltage and current signal. A rational analysis is needed. There are many methods in harmonic analysis, such as traditional Fast Fourier Transform, Short Time Fourier Transform and Wavelet Transform. They have different analytical emphasis. Their theories is introduced in the thesis, and compare is made with the same object by emulate. Based of all, a method using Fast Fourier Transform combining with Wavelet Transform is discussed, named eliminating singularity point and detecting harmonic. Surveying power harmonic Using the special effect on detecting singularity point and high resolving degree in time domain of wavelet, combined with the exact frequency resolving ability of Fast Fourier Transform. The material process is given in the thesis, and it is compared with rational method by emulate as well. The emulating results are better than traditional harmonic analysis method's.