Study On Power System Harmonics And Its Suppression Technology

With the development of the power system and the opening of the electricity Market, the power quality problem is receiving increasing attention.The pollution of the harmonies to the grid is inereasingly severe, owing to the Prevalence of the non-linear loads (harmoniesourees). So, the harmonic and its suppression teehnology is becoming the topic of commone oncern worldwide.A general description of development of harmonic around the world is given in this thesis at fist. It simply introduces the main mode of suppressing harmonic, the development of passive filter and active power filter, and the trends in APF. The basic concepts of electric harmonic as well as non-linear loads harmonic source production and influence are presented, and analyzed several non-linear loads harmonic source. Afterward mathematical model to the non-linear loads harmonic source is constructed, and drawn the conclusion by the mathematical formula. The simulation model of non-linear loads harmonic source power is giver in SIMULINK environment of MATLAB6.5 software. Simulation research proved the non-linear loads user influence the linear loads user.At the monment, in harmonic suppress aspect, it has had practical and mature passive thchnique, but it has many disdvantages. Therefore, these years much research turns to the actie power filter for its prior function of compensating harmonics dynamically. This thesis put forward an improved harmonic detecting based on instantaneous reactive power theory considering that the power system is often under imbalance in our country, and a harmonic detection method of the three-phase three-line parallel active power filter-the harmonic current deteetion method i P ? iq based on the instantaneous reaetive power theory, and performs simulation analyses in two different case, the steady system and the abrupt load changes. This thesis conducts researeh of the controlling method of the current of the parallel active power filter, and chooses the Hysteresis Current Control manner as the controlling strategy.Finally, this thesis develops a three-phase three-line parallel active power filter with the above harmonic detecion approach and controlling method,and conducts simulation experiments with Matlab, whose results verify the good compensation charaeteristics and performance of the filtering device.