Analysis Of Harmonics In Low-voltage Electricity Distribution Grid

With the progress of society and technology, various new electrical devices have been widely used in all fields in society. Because of the need of high safety and high exactitude for the function of the devices, it is more exacting on the utilization and demand of electricity. However, the massive use of non-linear loads has incurred heavy pollution of electricity and jeopardized the safety function of the system and the electrical devices. Based on the actual situations of low-voltage electricity distribution grid in Nanning City, this paper mainly discusses following issues:1. The basic concepts of electric harmonics are presented. the characteristics of various common harmonics in low-voltage electricity distribution grid are analyzed and discussed.2.Harm of harmonics to electric supply devices and amplifying mechanism of capacitor to electric harmonics currents are summarized. The influences to electricity grid loss and electrical measurement due to the existence of harmonics power-output are analyzed.3. The theory of harmonics measurement, Fast Fourier Transform Algorithm (FFT) and its improved algorithm are studied. Thecharacteristics of various types of harmonics analyzer at present are compared, and according to study object of this thesis, appropriate harmonics measurement analyzer is selected.4. The electric harmonics data of non-linear illuminating loads in one auditorium are collected and analyzed. From electricity distribution device and wave filter equipment reconstruction these two aspects, control measures of harmonics for low-voltage electricity distribution grid are comprehensively discussed, and control scheme pertaining to the existing problems is put forward. After one more harmonics measurement of the low-voltage electricity distribution grid that has adopted harmonics control measures, the data result shows that harmonics obvious improves.