Research On Islanding Detection Of Distributed Generation System

Nowadays, with the increasing consumption of traditional fossil fuels, as well as the urgent demand of environmental protection, the traditional large-scale centralized power generation is being replaced by the new power mode, like distributed generation (DG). The development and application of DG technology has become a worldwide trend. And with this trend, the related security technology of DG systems is more and more demanding. Research of islanding detection method is a key to ensure the safety and stability of DG systems.This thesis expounded the concept of DG system and the cause of islanding, then analyzed and discussed the requirement and the harm of the islanding effect, as well as the necessity of islanding detection. Introduced the international standards for islanding detection and anti-islanding test circuit used in experimental validation. Comparatively evaluated the advantages and disadvantages of common islanding detection methods.The NDZ (None Detection Zone) and the THD (Total Harmonic Distortion) of Active frequency-shift detection and Sandia detection are analyzed in the thesis. Based on analysis the relationship between NDZ and algorithm parameters are deduced, and this thesis proposed an adaptive active frequency drift with positive feedback detection method, and tested it through simulation.As kind of special power line communication signal, the power frequency distortion signal is applied in the islanding detection. The coupling feature of power frequency distortion signal transmitted through distribution network are analyzed in the thesis. And fast independent component analysis (FastICA) was applied as signal detection method. To solve the single channel blind sources separation problem, a single channel FastICA was proposed, and proved valid through Matlab/Simulink experiment.