Research Of The Methods For Measurement And Analysis On Power System Harmonics

As everyone knows, harmonics measurement and harmonics analysis has becomes one important research direction in the field of power system. Recently, with the widespread application of various kinds of electrical and electronic devices (mainly some non-linear equipment), harmonics pollution is becoming more and more serious, power quality comes down and different kinds of fault and accident happen often. As a result, to prevent the harmonic disturbance and improve the power quality, real-time measurement and real-time analysis of harmonic component produced by power network or by non-linear power consumption devices is necessary to grasp the actual conditions of the harmonics on power system in real time.This thesis systematically introduces the methods of measurement and analysis on power system harmonics, and some important conclusions have been induced from the simulation on MATLAB. The thesis includes the following contents:Firstly, some basic conception of the harmonics is introduced resumptively, main methods and history , present situation and development of harmonics measurement and harmonics analysis are summarized. several kinds of harmonics analysis algorithm at present commonly used are derived in detail, it has been reviewed that the theory of quasisynchronization and its application in the harmonics analysis ,also simulation on MATLAB is done in case of synchronized sampling, non-synchronized sampling and existence of disturbance.Secondly, the reason of frequency spectrum leaks has analyzed in detail, it is derived that the window function and DFT algorithm of harmonics analysis algorithm, and simulation on MATLAB is done in case of synchronized sampling, non-synchronized sampling and existence of disturbance, and the curve of error is also given. In allusion to the merit and shortcoming of each kind of window, a kind of association analytical method is proposed, which conbines the advantages of hanning window and triangular window together,thus it can reach higher precision. The simulation result demonstrate the feasibility of the method, it can reach higher precision.Finally, A harmonics monitoring instrument based on DSP is also studied, the hardware scheme and the software flow chart are given in the thesis. And itis simply introduced that several key links——Data processing module (DSP),Data collection module and Man-machine interface module.