Research On Power Quality Transient Disturbances Based On Fractal And Lifting Complex Wavelet

In modern power system, with the extensive use of nonlinear loads and sensitiveelectronic equipment in the power grid, the power quality transient problems are moreand more serious. To ensure that all electrical equipment operate properly and reliably,we must take measures to improve power quality.So, it is necessary to depth study thetheory, the detection and related analysis techniques of the power quality transient.In practice, in order to accurately detect power quality transient disturbances,thereby improving power quality transient, depth research is conducted at home andabroad, and a number of methods are proposed such as wavelet transform, S transform,short time Fourier transform and so on. Based on analysis of relevant literature andprevious studies,the main research works and achievements are outlined as follows:Firstly, According to power quality transient disturbances singularity,startingfrom graphical recogniton, a method of analyzing overlapped power quality transientdisturbances based on fractal entropy analysis is presented. Matlab simulation resultsshow that the proposed method can effectively identify the overlapped power qualitytransient disturbances with minor magnitude.Secondly, In order to meet the requirements of real-time disturbances detection,a multi-resolution analysis method of power quality transient disturbances based onwavelet fractal is presented. Matlab simulation results show that the proposed methodis very robust and adaptable,and can analyze transients with minor magnitude.And italso can detect transients quickly and can be parallel executed.Thirdly, in view of all these characteristics of complex wavelet carryingamplitude and phase information and lifting algorithm having low computationalcomplexity, a method of detecting and localizing power quality transient disturbancesbased on lifting complex wavelet is presented. the amplitude and phase informationafter lifting complex wavelet transform are applied to localizing transient powerquality disturbances and estimating amplitude. Matlab simulation results show thatthe proposed method is simpler,faster,and accurater.