Island Detecting Techniques On Grid-connected Distributed Photovoltaic Power Generation System

In recent years, people’s life is affected by the increasing pollution of the environmentmore and more. The consumption of coal, oil and other traditional energy not only pollute theenvironment, and they are non-renewable and limited. People have begun to seek new sourcesof energy before the energy depletion. The solar energy is clean and pollution-free, it is notsubject to regional and resource constraints when using. It just meets the demand of today’senvironmental protection. Due to the government’s vigorously support and the gooddevelopment environment, the photovoltaic industry is more and more valued in recent years,and it triggered a solar heat, so the photovoltaic industry has been developing rapidly. But thephotovoltaic industry is in a stage of development, there are still some problems. Theislanding is not only a threat to personal safety, and may lead damage to the power systemequipment. Thus, the grid-connected distributed photovoltaic power generation system mustbe set the measure of island protection. Islanding can successfully detect involve the issues ofproperty and personal safety and so on. It influences the development of photovoltaic powergeneration systems, so the research of the island detecting techniques on photovoltaic powergeneration system is very important.This paper briefly describes the concept and effect mechanism of the island, a severalmain island detection technology in recent years is introduced: the remote detectiontechniques, active island detection techniques, passive detection techniques. In this paper, thethree kinds of island detection techniques are analyzed. Due to the high cost of testingtechnology, the small and medium-sized distributed generation system shall not adopt it. Thesystem in the practical application of island techniques in China should be combined with atleast each a kind of active and passive method, it is given priority to with active techniquesand the passive techniques is complementary, they were combination. This paper puts forwarda way based on different disturbance of Active detection method of low harmonic islanddetection technology from disturbance mechanism of Active method. The AFD (ActiveFrequency Drift, AFD) technique is compared to illustrate the advantages of low harmonic technique. This paper expounds the theory of the two islands detecting techniques, and thesimpowersystem toolbox of Matlab/Simulink is used to build the single-phase gridphotovoltaic power generation system, two kinds of techniques is made for the simulationexperiment. The experimental results proved that the low harmonic technique in the detectionspeed and harmonic is superior to AFD technique. In order to further test the low harmonictechnique, this paper made a experiment in single phase photovoltaic system on two islanddetecting techniques for detection, and the experiment results are analyzed.The low harmonic technique is improved in this paper in the process of research. Theimproved technique is more practical. This paper analysis the theory of the improvedtechnique, and the two techniques’ non-detection zone are analyzed. The simulationexperiment of the low harmonic technique is made, and it was tested on the single phasephotovoltaic system at the same time, the results are analyzed in this paper.Finally, the paper make summarizes for the main work, and prospect the demands and tendency of thedevelopment of the island detecting techniques in the future.