Study On Harmonic Detection Based On Load Characteristic Analysis Method

With the advance of society, an expanding number of more complicated power electronic equipments and nonlinear equipments have been put into use in the power system, giving rise to quantities of harmonics, which makes the power quality problems become increasingly serious. Firstly, modern electronic equipments are pretty sensitive to the grid’s interference. What’s more, due to the fact that the harmonic sources of the point of common coupling(PCC) can interact with each other, there is a widespread dispute about the responsibility of harmonic pollution between the users and the suppliers. As a consequence, it is of great significance to detect the harmonic, delimit the responsibility of harmonics and solve the problems of harmonic pollution, etc.This paper made the following studies on the harmonic detection and harmonic division of responsibilities :Firstly, the existing harmonic detection methods for harmonic detection are summarized in this article, and a comprehensive analysis of the various methods of advantages and disadvantages was included as well, on the basis of which, a profound study of the harmonic detection based on the analysis of load characteristics based on the analysis of load characteristics was put forward in this paper, describing the effectiveness and feasibility of it. Then from the mechanism generated from harmonic,on the condition that load parameters of the system side and the user side are unknown,build and derived the time-domain mathematical model and propose a harmonic source detection method based on the analysis of load characteristics by using the physical relations between voltage and current at the point of common coupling. In addition, the introduction of singular value decomposition(SVD) and improved matrix pencil algorithm solve the sampling frequency problem of measuring matrix singular fitting voltage and current signals. And through simulation, load characteristics equivalent parameters can be identified so that the harmonic can be detected, which verifies the correctness and feasibility of the method.In this paper, taking advantage of PSCAD / EMTDC software, widely used in the field of power research, to build simulation model and MATLAB to program and process simulation data verifies the validity and effectiveness of the algorithm through three numerical examples. Furthermore, to divided harmonic responsibility, this paper introduces the concept of impedance of non-linearity and load of non-linearity. On thebasis of the detected harmonic, it evaluates the distortion level of various non-linear loads and the harmonic responsibility correctly, which is also used as the formulation basis of relevant restraining strategy to lay a foundation for the next harmonic pollution control and provide a useful reference. By simulation, it has been verified that load non-linearity was not affected by the background harmonics and the same load at different voltage levels and different backgrounds harmonics was of consistency.