Power Quality Disturbance Signal Analysis Method Based On The Improved Generalized S-transform

Network structure and load structure of modern power systems are undergoing tremendous change, distributed power grid, high-speed trains and a series of non-linear loads put into operation, the rapid development of power electronic devices, resulting in power quality problems become increasingly serious, get the attention of power department and users. Rapid and accurate detection of power quality parameters and identification of the type of power quality disturbances on power quality governance and enhance is of great significance. In this paper, we study generalized S-transform and applied and applied to the power quality disturbance signal analysis, achieved real-time detection of harmonics and inter-harmonics and identification of power quality disturbance.Harmonics and inter-harmonics detection is one of the most important elements of power quality disturbance signal detection. For the detection of harmonics and inter-harmonics, especially to interference problem of inter harmonics and other difficult issues, we propose a method based on fast adaptive discrete generalized S-transform harmonics and inter-harmonic detection. First, the fast Fourier transform is used to estimate the information frequency Secondly, the folded window is applied to solve the signal spectrum aliasing caused by local discretization, and the adaptive window function parameters is selected, in order to narrow the range of frequency domain analysis, save calculation time, get the more reliable time-frequency information. These measures can effectively restrain harmonics, inter-harmonics and noise between mutual interference, improve the signal the estimation precision of the harmonics and inter-harmonics parameters and time orientation. The validity of the proved method has been verified by the simulation results of steady and dynamic power signals of specific numerical example with harmonics and inter-harmonics.Extraction of disturbance characteristics and classification from the disturbance signal in the mass, is the foundation of power quality analysis and control.This paper put forward a kind of decision tree and the type of disturbance identification method based on fast adaptive bi-gaussian generalized S-transform. First, the fast Fourier transform is used to analyse signal and based on noise power of the maximum threshold set to mask the redundant information, to speed up the operation speed of the object; Secondly, instead of the traditional Gaussian window with bi-gaussian window, to solve the traditional S transform disturbance detection problem in starting and ending time when the disturbance amplitude curve changes slowly, and an adaptive parameter selection window function is used to get the frequency of the signal obtained by converting analog matrix information more reliable. Finally, new index is introduced to accurately estimate power quality disturbance start-stop time information, effective features classification is extracted, design classification discriminant tree and identify types of disturbance. With the aid of MatlabR2010b simulation platform, through the analysis results of twelve kinds of power quality disturbance signal, verify the effectiveness of the proposed method.